Vulnerability Assessment of Selected Buildings
Designated as Shelters
Antigua and Barbuda

Organization of American States
General Secretariat
Unit for Sustainable Development and Environment

USAID-OAS Caribbean Disaster Mitigation Project
OAS-ECHO Project to Reduce the Vulnerabilityof School Buildings to Natural Disasters
1998


This report was prepared by
Tony Gibbs of Consulting Engineers Partnership Ltd.

TABLE OF CONTENTS

1 INTRODUCTION

1.1 The Purpose of the Project
1.2 Terms of Reference
1.3 Natural Hazards in the Caribbean
1.3.1 Earthquakes
1.3.2 Volcanic Activity
1.3.3 Tsunamis
1.3.4 Hurricanes
1.3.5 Torrential Rains
1.3.6 Storm Surge
1.3.7 Landslides

2 INVESTIGATION PROCEDURE

2.1 Briefing
2.2 Field Surveys
2.3 Field Reviews
2.4 Desk Studies

3 RESULTS

3.1 Vulnerability to Hurricanes
3.1.1 General Observations
3.1.2 Aspects of Vulnerability
3.1.3 Summary of Results
3.2 Vulnerability to Torrential Rain
3.2.1 General Observations
3.2.2 Summary of Results
3.3 Vulnerability to Earthquakes
3.3.1 Multi-hazard Design
3.3.2 Differences Between Designing Against Earthquakes and Hurricanes
3.3.3 Aspects of Vulnerability
3.3.4 Summary of Results

4 GENERAL ISSUES

4.1 Impact of Hurricanes on Caribbean Schools
4.2 Hazards versus Disasters
4.3 Codes and Standards
4.4 The Regulatory Environment
4.5 Public Awareness
4.6 Vulnerability Surveys
4.6.1 Qualitative Assessment
4.6.2 Analytical Evaluation
4.7 Disaster Mitigation after the Event
4.8 Maintenance as a Tool for Mitigation

5 HURRICANES LUIS AND MARILYN IN ANTIGUA AND BARBUDA

5.1 Damage and Repairs
5.2 Recommendations
5.3 Classes of Vulnerability
5.4 Further Work

Appendix I Survey Forms

Appendix II Technical Paper (only introduction available in web format)

Appendix III   Photographs of Selected Buildings Designated as Shelters in Antigua and Barbuda


1 INTRODUCTION

1.1 The Purpose of the Project

Throughout the world, including the Caribbean, natural hazards cause as much damage to educational facilities as they do to buildings of less importance. This is both regrettable and avoidable. Educational facilities deserve special attention because of their roles during the active periods of storms and also as post-disaster assets.

It is traditional for schools to be used as hurricane shelters. It goes without saying, therefore, that the damage and destruction of schools would put the sheltered population at risk during severe storms. Also, damage and destruction of such schools would not facilitate the use of school buildings for temporary housing after hurricanes. The longer-term problem of loss of educational facilities is arguably even more severe. If the children are not at school the parents' work is often adversely affected (in part because of "baby-sitting" problems). There is also the inevitable disruption of the pupils' education.

It is often said that safe buildings may not be affordable, especially in relatively poor developing countries. This is a fallacy. Particularly with respect to hurricane resistance, safe buildings are not only technically feasible but also achievable at very modest cost. This thesis has been tested and confirmed on several occasions over the years.

The Caribbean Development Bank (CDB) proposes to assist its borrowing members in reducing the vulnerability of designated shelters to natural hazards. The initial screening of these designated properties is being carried out in some of the CDB member countries through the auspices of the Organisation of American States (OAS) using CDMP [1] and ECHO [2] funding.

It is recognised that the suitability of properties for use as emergency shelters depends on several factors other than structural safety. Some of these factors are location, size, water storage and supply, sanitary facilities, kitchen facilities, standby power and telecommunications within the facility and externally. Most of these issues are already being addressed by other agencies. The focus of this study is on the physical vulnerability of the built facilities to wind forces, torrential rain and seismic forces. This initial screening will provide the relevant local agencies with some of the input required for selection of properties for the follow-on, CDB-funded projects.

1.2 Terms of Reference

The portions of the overall Terms of Reference (ToR) relevant to the subject of the present report are:

As articulated above, an important objective of this project is technology transfer and the broadening of the pool of "disaster mitigation" engineers in the region. Therefore, the active involvement of local engineers (assumed to be from the relevant public works departments) was essential.

1.3 Natural Hazards in the Caribbean

The primary natural hazards facing the islands of the Caribbean are earthquakes and hurricanes. Some of the islands are also subjected to instances of volcanic activity. There are also the related hazards of tsunamis and storm surge.

Torrential rains can also, by themselves, be considered natural hazards since they often occur without the concurrent occurrence of hurricanes and sometimes result in disastrous flooding of low-lying areas. Likewise, some landslides are naturally occurring, isolated events.

1.3.1 Earthquakes

All of the Commonwealth Caribbean countries, with the exceptions of Bahamas and Guyana, lie close to the known tectonic plate boundaries. The North American Plate is moving westward with respect to the adjacent Caribbean and South American Plates at a rate of approximately 2 centimetres per year. A moderate level of inter-plate activity is generated along these boundaries. Along the northern margin, including areas in the vicinities of Jamaica and the Virgin Islands, moderate earthquakes of shallow depth are generated. Near the plate boundaries there are also intra-plate earthquakes. In the northern Caribbean these intra-plate earthquakes are caused by internal deformation in a slab of the North American Plate. Concentrations of these earthquakes occur at depths of up to 200 kilometres.

Seismic events in the Eastern Caribbean are principally associated with a subduction zone at the junction of the Caribbean Plate and the North American Plate. The North American Plate dips from east to west beneath the Caribbean Plate along a north-south line just east of the main island arc. This leads to a moderate level of inter-plate seismicity. Superimposed on this is a pattern of intra-plate activity. There is a concentration of such activity in the Leeward Islands where the subduction of the Barracuda Rise imposes additional stresses on both the "subducted" North American Plate and the overriding Caribbean Plate. The earthquakes there are generally shallow. In the region north-west of Trinidad there is another concentration of earthquake activity where the strike of the plate boundary changes direction. These earthquakes are of intermediate depth.

Over the past forty-five years a considerable amount of research has been carried out on the seismicity of the Caribbean by the Seismic Research Unit (SRU) of the University of the West Indies (UWI). The engineering community has been requesting more and more assistance from the SRU in interpreting the fundamental research and developing "code" values for seismic forces for use in structural design. The most recent published work in this field is that of SRU's former head, Dr John Shepherd, now at Lancaster University (England).

The Pan-American Institute of Geography and History (PAIGH) is based in Mexico City. The Geophysical Commission of PAIGH is the executing agency for a major project (funded by IDRC [4]) for preparing Seismic Hazard Maps for Latin America and the Caribbean and headed by Dr J G Tanner. Dr John B Shepherd participated in this project as the Caribbean specialist.

The final report and mapping from this project indicate that Antigua and Barbuda lie between the iso-acceleration lines representing 500 gals and 800 gals [5]. These are peak ground accelerations with a probability of non-exceedance of 90% in 50 years. The Caribbean Uniform Building Code (CUBiC), which is incorporated in the draft Antigua - Barbuda Building Code [6], assigns a zone factor (Z) of 0.75 to Antigua and Barbuda, however the PAIGH iso-acceleration lines would justify a zone factor of 1.0. Both of these references indicate a serious earthquake hazard for Antigua and Barbuda.

1.3.2 Volcanic Activity

Several of the islands of the Eastern Caribbean are volcanic in origin. The volcanoes there are considered to be either active or dormant. Antigua does not exhibit volcanic activity.

1.3.3 Tsunamis

A tsunami (or seismic sea wave or tidal wave) is a series of ocean waves generated by any large-scale, short-duration disturbance of the free surface of the ocean. The majority are related to tectonic displacements associated with earthquakes at plate boundaries. However, erupting volcanoes, landslides or underwater explosions can also generate tsunamis. In the open ocean, tsunamis may have wavelengths of up to several hundred miles but heights of less than 1 meter. Because this ratio is so large, tsunamis can go undetected until they approach shallow waters along a coast. Their height as they crash upon the shore mostly depends on the geometry of the submarine topography offshore, but they can be as high as 30 meters.

A tsunami travels at an average velocity of 500 to 600 kilometres per hour rising to a maximum of 800 km/h. Therefore within one hour of a major occurrence at Kick 'em Jenny (just north of Grenada), many of the islands of the Eastern Caribbean (including Antigua and Barbuda) will be affected. This, however, is outside the scope of this report.

1.3.4 Hurricanes

Much is not known about the storms that occurred in the Caribbean in the years before the advent of Columbus. But, of course, the European did not bring hurricanes to the Caribbean. Indeed the very name is derived from the Mayan storm god Hunraken and the Arawak word hurican, which meant the devil wind. The greatest of all recorded hurricanes occurred from 10th to 18th October 1780. Nearly 20,000 people perished as the storm hit virtually every island from Tobago in the south-east through the Windward and Leeward Islands and across to Hispaniola and Cuba. In the last 60 years in the Caribbean another 20,000 people have lost their lives because of hurricanes.

The Caribbean lies in the North Atlantic Ocean, one of the six main tropical areas of the earth where hurricanes may develop every year. Within the 111 years between 1886 and 1996, approximately 1000 tropical storms have been recorded in the North Atlantic. About half of these attained hurricane strength.

The destructive potential of a hurricane is significant due to high wind speeds and torrential rains that produce flooding and occasional storm surges with heights of several feet above normal sea level.

The pattern in recent times has been a reduction of deaths and injuries (because of better warning systems and other preparedness activities) and an increase in property damage (because of commercially-driven unsuitable building practices and locations).

The Caribbean Uniform Building Code (CUBiC), which is incorporated in the OECS Antigua & Barbuda Building Code, assigns a reference pressure of 0.82 kPa [7] to Antigua and Barbuda. This is equivalent to a 10-minute sustained wind speed of 37.0 m/s (83 mph) or an equivalent 3-second gust speed of 56 m/s [8] (125 mph). These figures relate to a 50-year return period.

1.3.5 Torrential Rains

Although heavy rains often accompany hurricanes, severe rainfall events resulting in flooding are also, and frequently, associated with troughs and tropical depressions. The risk of flooding is therefore not restricted to, nor more likely to occur, during hurricane events.

Drainage systems and structures in the Caribbean are generally designed for rainfall events having return periods of 20 years. This means that such systems are likely to become overloaded and cause some degree of flooding when rainstorms are experienced with return periods greater than 20 years. No guidance on this is provided in CUBiC. However, consideration should be given to moving this common standard to a longer return period. Intensity-duration-frequency relationships for rainfall events are required for rational engineering analysis. These are available from the Caribbean Meteorological Institute for some Caribbean islands.

The damage caused by flooding depends on the type and elevation of facilities in the location. The results of flooding may range from the inconvenience of temporarily submerged driveways to the loss of equipment and finishes inside flooded buildings and consequential disruption of the functions.

Flooding has been the cause of many of the deaths and of much property damage as well. Clearly, location is critical when it comes to flood risk. Low-lying lands, river banks and lands adjacent to gullies are to be avoided if possible. If not, deliberate drainage measures must be taken. Usually this is a municipal responsibility, at least in terms of overall control, since what happens to one property can easily be affected by a neighbour's actions.

The design of external works for shelter premises would include consideration of local flooding. It would not be practical to study the overall catchment area for the design of each particular site. However, some general appraisal of the adjacent areas should be carried out as input for the design of on-site drainage structures.

1.3.6 Storm Surge

Storm surge is associated with hurricanes and consists of unusual volumes of water flowing onto shorelines. Storm surge has been responsible for much of the damage caused by hurricanes, especially in large, low-lying coastal settlements.

Storm surge is a complex phenomenon which behaves quite differently from one shoreline to another. The several main components governing their behaviour are:

Astronomical Tide: water levels due to tidal variation;
Initial Water Level: elevated basin-wide water levels caused by larger storms;
Pressure Deficit: elevated water levels caused by low pressure systems;
Inland Runoff: raised water levels in rivers and sea outfalls due to prolonged rainfall;
Current Surge: ocean currents caused by high winds leading to the "piling up" of shallow waters;
Wave Setup: water accumulating from continuous trains of waves on breaking on the shoreline; and
Wave Action & Runup: effect of actual waves superimposed on the above factors.

The increase in coastal settlement has put much of our economic investment at risk from sea damage. Future rises in sea level can only make this condition more acute. Storm surge caused by hurricanes causes the most dramatic damage. Waves cause damage without accompanying surge but they are also superimposed on storm surge.

As well as causing flooding and damage to coastal structures, storm surge may also precipitate flooding further inland through the blockage of the outfalls of drainage systems.

This is outside of the scope of the present exercise.

1.3.7 Landslides

Most landslides in Caribbean islands cannot be regarded as natural hazards since they are brought about by inappropriate farming practices although triggered by natural events. Another man-induced class of landslides is road construction in mountainous areas. Often the cut embankments are too steep for stability. Often the down-slope fills are unstable.

There are, however, a few situations where nature itself produces the events. This phenomenon is outside the scope of this report.


2 INVESTIGATION PROCEDURE

2.1 Briefing

On 13 January 1998 an initial briefing took place at the Public Works Department with Wesley James. The overall programme was explained and Consulting Engineers Partnership Ltd (CEP) delivered the survey forms to Mr James.

The forms are:

2.2 Field Surveys

The shelters that are school facilities on the list to be surveyed were:

Individual Building and Code Number

Name

Location

ANB-PPS

Parham Primary School

Parham Town

ANB-PMS

Princess Margaret School 

St. John’s

ANB-LPS

Liberta Primary School

Liberta

ANB-AGH

Antigua Girls High School

St. John’s

ANB-BPS

Bolans Primary School

Bolans Village

ANB-UPS

Urlings Primary School

Urlings Village

ANB-GRE

Greenbay Primary School

St. John’s

ANB-NWS

New Winthropes Primary School

Barnes Hill

ANB-TNK

T.N. Kirnon School

St. John’s

ANB-AGS Antigua Grammar School St. John’s

ANB-JHS

John Hughes Primary School

John Hughes

ANB-FIS

Five Island School

St. John’s

ANB-JTA

J.T. Ambrose School

All Saints

ANB-CCS

Cobbs Cross Primary School

Cobbs Cross

ANB-INT

Intrade

   St. John's

ANB-HTS

Holy Trinity School

Codrinton, Barbuda

ANB-GPS

Glanvilles Primary School

Glanvilles Village

ANB-BDS

Bendals Primary School

Bendals

ANB-OCS

Ottos Comprehensive School

St. John’s

Note: Intrade is not a school

Wesley James proceeded with the surveys and on 10 March 1998 Tony Gibbs visited Mr James in Antigua to review his progress and answer any queries. Wesley James completed the field surveys including all photographs by 17 April 1998.

2.3 Field Reviews

Field reviews were undertaken by CEP’s David Folkes in the company of Wesley James on 17, 18, 24 and 25 of April, 1998.

2.4 Desk Studies

To assist with the determination of vulnerability to hurricanes (and in accordance with the ToR) the software package WIND-RITE was utilised. WIND-RITE is a software system developed by the Wind Engineering Research Center at Texas Tech University, Lubbock, TX in conjunction with the Insurance Institute for Property Loss Reduction. This program is used to establish a relative grade for the wind resistance of buildings by assigning various vulnerability weights to: site environment, roof envelope, wall envelope, structural framing, and other secondary considerations.

A relative grade between 1 and 10 is assigned to a building during the evaluation process. A relative grade of 1 indicates that the building is highly resistant to wind-induced damage (less damage), whereas a building which receives a relative grade of 10 is highly susceptible to wind-induced damage (extensive damage). For non-engineered construction, a score of five would be considered very satisfactory.

To assist with the determination of vulnerability to earthquakes (and in accordance with the ToR) the methodology of Ahmed F Hassan [9] was used. This methodology relies mainly on readily accessible data for an existing building such as the dimensions and arrangement of its structural elements and the floor area. Masonry walls, concrete columns and steel columns are given progressively higher weightings in determining their contributions to seismic resistance. The end result is a comparative assessment of seismic vulnerability. A copy of Hassan’s paper is provided in Appendix II.


3 RESULTS

3.1 Vulnerability to Hurricanes

3.1.1 General Observations

It would not be unreasonable for the Government to require that its new, formally-designed, school buildings would have the capacity to be largely undamaged by a 50-year-return-period hurricane.

The objective stated above requires simply the application of known technology by the school's architects and engineers to:

The next requirement is for faithful attention to be paid during construction to the details incorporated in the drawings, schedules and technical specifications for the project. Supervision and inspection are central to success in this area of execution.

The final requirement is for the property to be adequately maintained.

The above precepts seem simple enough. Yet schools are often damaged and indeed sometimes destroyed by hurricane events no worse than the "design" storm. That design storm cannot be less than (and could reasonably be greater than) the "50-year" storm. These failures come about because of the failure of the systems (or the inadequacy of the systems) set up to order the construction industry and to maintain public property.

3.1.2 Aspects of Vulnerability

The experience of recent hurricanes has demonstrated that most failures occur to roofs, windows and external doors. In a very few cases there is damage (or collapse) of walls. In even fewer cases there is foundation failure. The experience in Antigua & Barbuda provides confirmatory evidence of this pattern.

Roofs:

Windows (and other openings):

External Doors:

3.1.3 Summary of Results

The table below summarises the conclusions of the survey with respect to wind vulnerability. A higher WIND-RITE Rating indicates a higher vulnerability to hurricane events.

Property

Individual Building and Code Number

Description

Vulnerable Areas

WIND-RITE Rating

Parham Primary School ANB-PPS-01 Single storey building providing approximately 1410 sq-ft of sheltered floor area.
Constructed in 1971.
  • Roof timber connections
  • Metal sheeting connections
  • Breeze block windows
8.44
ANB-PPS-02 Single storey building providing approximately 1260 sq-ft of sheltered floor area.
Constructed in 1971.
  • Roof timber connections
  • Metal sheeting connections
  • Breeze block windows
9.25
ANB-PPS-03 Single storey building providing approximately 1300 sq-ft of sheltered floor area.
Constructed in 1971.
  • Roof timber connections
  • Metal sheeting connections
  • Breeze block windows
9.25
Princess Margaret School ANB-PMS-01 Single storey building providing approximately 3340 sq-ft of sheltered floor area.
Constructed in 1960s.
  • Roof timber connections
  • Metal sheeting connections
  • Breeze block windows
  • Aluminium and timber louver, and glass windows
9.07
ANB-PMS-02 Single storey building providing approximately 2850 sq-ft of sheltered floor area.
Constructed in 1955.
  • Metal sheeting connections
  • Breeze block windows
  • Aluminium and timber louver, and glass windows
8.78
Liberta Primary School ANB-LPS-01 Single storey building providing approximately 3970 sq-ft of sheltered floor area.
Constructed in 1960.
  • Roof timber connections
  • Metal sheeting connections
  • Breeze block windows
  • Timber window shutter connections
N/A
ANB-LPS-02 Single storey building providing approximately 2940 sq-ft of sheltered floor area.
Constructed in 1960.
  • Roof timber connections
  • Metal sheeting connections
  • Breeze block windows
  • Timber window shutter connections
N/A
Antigua Girls High School ANB-AGH-01 Two-storey building providing approximately 10340 sq-ft of sheltered floor area.
Unknown construction date.
  • Metal sheeting connections
  • Glass and aluminium louver windows
8.69
ANB-AGH-02 Single storey building providing approximately 3760 sq-ft of sheltered floor area.
Unknown construction date.
  • Metal sheeting connections
  • Aluminium louver windows
8.49
Bolans Primary School ANB-BPS-01 Single storey building providing approximately 4410 sq-ft of sheltered floor area.
Constructed in 1973.
  • Roof timber connections
  • Metal sheeting connections
  • Breeze block windows
  • Aluminium louver windows
N/A
ANB-BPS-02 Single storey building providing approximately 2730 sq-ft of sheltered floor area.
Unknown construction date.
  • Roof timber connections
  • Metal sheeting connections
  • Breeze block windows
  • Aluminium louver windows
9.36
Urlings Primary School ANB-UPS-01 Single storey building providing approximately 4510 sq-ft of sheltered floor area.
Constructed in 1981-82.
  • Metal sheeting connections
  • Aluminium louvers
8.54
ANB-UPS-02 Single storey building providing approximately 1100 sq-ft of sheltered floor area.
Constructed in 1986-87.
  • Metal sheeting connections
  • Aluminium louvers
N/A
Greenbay Primary School ANB-GRE-01 Single storey building providing approximately 2650 sq-ft of sheltered floor area.
Constructed in 1949.
  • Metal sheeting connections
  • Aluminium louvers
  • Breeze block windows
8.85
ANB-GRE-02 Two-storey building providing approximately 4480 sq-ft of sheltered floor area.
Constructed in 1949.
  • Metal sheeting connections
  • Aluminium louvers
9.32
New Winthropes Primary School ANB-NWS-01 Single storey building providing approximately 1960 sq-ft of sheltered floor area.
Constructed in 1944-45.
  • Open timber windows
  • Breeze block windows
  • Un-reinforced stone wall
  • Cracked columns
N/A
ANB-NWS-02 Single storey building providing approximately 1230 sq-ft of sheltered floor area.
Constructed in 1992.
  • Open timber windows
  • Un-reinforced stone wall
  • Roof timber connections
  • Metal sheeting connections
9.38
T.N. Kirnon School ANB-TNK-01 Two-storey building providing approximately 5490 sq-ft of sheltered floor area.
Constructed in late 1800s or early 1900s.
  • Un-reinforced masonry wall
  • Open timber windows
  • Roof timber connections
  • Metal sheeting connections
9.04
ANB-TNK-02 Single storey building providing approximately 3080 sq-ft of sheltered floor area.
Constructed in 1981-82.
  • Aluminium louvers
  • Roof timber connections
  • Metal sheeting connections
7.41
Antigua Grammar School ANB-AGS-01 Two-storey building providing approximately 4960 sq-ft of sheltered floor area.
Constructed in 1884.
  • Un-reinforced masonry walls
  • Roof timber connections
  • Metal sheeting connections
  • Glass windows
8.93
ANB-AGS-02 Two-storey building providing approximately 1550 sq-ft of sheltered floor area.
Constructed in 1985-86.
  • Aluminium louvers
  • Roof timber connections
  • Metal sheeting connections
7.95
John Hughes Primary School ANB-JHS-01 Single storey building providing approximately 2800 sq-ft of sheltered floor area.
Unknown construction date.
  • Breeze block windows
  • Metal sheeting connections
8.91
Five Island School ANB-FIS-01 Single storey building providing approximately 2860 sq-ft of sheltered floor area.
Constructed in 1960s.
  • Breeze block windows
  • Metal sheeting connections
9.43
ANB-FIS-02 Single storey building providing approximately 1610 sq-ft of sheltered floor area.
Constructed in 1960s.
  • Breeze block windows
  • Metal sheeting connections
9.65
J.T. Ambrose School ANB-JTA-01 Single storey building providing approximately 3270 sq-ft of sheltered floor area.
Unknown construction date.
  • Aluminium louvers
  • Breeze block windows
  • Roof timber connections
  • Metal sheeting connections
8.91
ANB-JTA-02 Single storey building providing approximately 2500 sq-ft of sheltered floor area.
Constructed in 1997.
  • Metal sheeting connections
7.95
ANB-JTA-03 Single storey building providing approximately 1530 sq-ft of sheltered floor area.
Constructed in 1997.
  • Metal sheeting connections
8.84
Cobbs Cross Primary School ANB-CCS-02 Single storey building providing approximately 3680 sq-ft of sheltered floor area.
Constructed in 1945-46.
  • Breeze block windows
8.37
Intrade ANB-INT-01 Two-storey building providing approximately 4060 sq-ft of sheltered floor area.
Constructed in early 1960s.
  • Glass windows and doors
  • Some un-reinforced masonry walls
  • Roof missing
8.19
Holy Trinity School ANB-HTS-01 Single storey building providing approximately 4080 sq-ft of sheltered floor area.
Unknown construction date.
  • Breeze block windows
  • Roof timber connections
  • Metal sheeting connections
N/A
ANB-HTS-02 Single storey building providing approximately 1870 sq-ft of sheltered floor area.
Constructed in 1981-82.
  • Aluminium louvers
  • Un-reinforced stone masonry walls
  • Roof timber connections
  • Metal sheeting connections
9.22
ANB-HTS-03 Single storey building providing approximately 4510 sq-ft of sheltered floor area.
Constructed in late 1950’s.
  • Roof timber connections
  • Metal sheeting connections
8.22
Glanvilles Primary School ANB-GPS-01 Single storey building. Providing approximately 2880 sq-ft of sheltered floor area.
Constructed in 1970’s.
  • Metal sheeting connections
8.85
Bendals Primary School ANB-BDS-01 Single storey building providing approximately 3330 sq-ft of sheltered floor area.
Constructed in 1988-89.
  • Metal sheeting connections
8.03
Ottos Comprehensive School ANB-OCS-01 Three-storey building providing approximately 2910 sq-ft of sheltered floor area.
Constructed in 1976.
  • Glass windows
N/A
ANB-OCS-02 Two-storey building providing approximately 3940 sq-ft of sheltered floor area.
Constructed in 1976.
  • Breeze block windows
8.17

Note 1: N/A indicates that a WIND-RITE result was not obtained due to insufficient survey information.
Note 2: All walls are concrete block masonry walls unless otherwise indicated

The WIND-RITE analysis results appear to indicate that the properties have an approximate equally high vulnerability to hurricanes. It should be noted that the WIND-RITE program will produce high vulnerabilities if the building has unprotected openings and light-weight sheeting. Since these vulnerable areas can be mitigated against relatively easily, it is not considered prudent to exclude a property from being considered as a shelter based on these results.

3.2 Vulnerability to Torrential Rain

3.2.1 General Observations

Property becomes vulnerable to torrential rain either directly, if the rain penetrates the building envelope, or indirectly, through the resultant flooding events. Improperly sealed window and door openings or roof covering can result in the immediate ingress of water, while poorly sited buildings, and/or buildings with inadequate or improperly maintained drainage systems can result in the property being vulnerable to flooding.

The not so immediate effect of flooding caused by torrential rains is the adverse effect it can have on the foundations of buildings.

Coastal areas can be particularly vulnerable to flooding especially if high tides accompany heavy rains. In addition, the groundwater level is generally higher in coastal areas resulting in less absorption by the ground and an increased incidence of flooding.

3.2.2 Summary of Results

The table below summarises the conclusions of the survey with respect to torrential rain vulnerability.

Property

Individual Building and Code Number

Location of Property

Vulnerable Areas

Parham Primary School ANB-PPS-01
  • Relatively flat topography
  • Rural location
  • Floor (flooding)
  • Breeze block windows
ANB-PPS-02
  • Relatively flat topography
  • Rural location
  • Floor (flooding)
  • Breeze block windows
ANB-PPS-03
  • Relatively flat topography
  • Rural location
  • Floor (flooding)
  • Breeze block windows
Princess Margaret School ANB-PMS-01
  • Relatively flat topography
  • Urban location
  • Floor (flooding)
  • Breeze block windows
ANB-PMS-02
  • Relatively flat topography
  • Urban location
  • Floor (flooding)
  • Breeze block windows
  • Aluminium louvers
Liberta Primary School ANB-LPS-01
  • Relatively flat topography
  • Residential rural location
  • Floor (flooding)
  • Breeze block windows
ANB-LPS-02
  • Relatively flat topography
  • Residential rural location
  • Floor (flooding)
  • Breeze block windows
Antigua Girls High School ANB-AGH-01
  • Relatively flat topography (low-lying)
  • Rural location
  • Floor (flooding)
  • Breeze block windows
ANB-AGH-02
  • Relatively flat topography (low-lying)
  • Rural location
  • Floor (flooding)
  • Aluminium louver windows
Bolans Primary School ANB-BPS-01
  • Relatively flat topography
  • Residential rural location
  • Floor (flooding)
  • Aluminium louvers
  • Breeze block windows
ANB-BPS-02
  • Relatively flat topography
  • Residential rural location
  • Floor (flooding)
  • Aluminium louvers
  • Breeze block windows
Urlings Primary School ANB-UPS-01
  • Relatively flat topography
  • Coastal location
  • Aluminium louvers
ANB-UPS-02
  • Relatively flat topography
  • Coastal location
  • Aluminium louvers
Greenbay Primary School ANB-GRE-01
  • Relatively flat topography
  • Residential location
  • Breeze block windows
ANB-GRE-02
  • Relatively flat topography
  • Residential location
  • Aluminium louvers
  • Breeze block windows
New Winthropes Primary School ANB-NWS-01
  • Sloped topography
  • Rural location
  • Floor (flooding)
  • Breeze block windows
ANB-NWS-02
  • Sloped topography
  • Rural location
  • Floor (flooding)
  • Open windows
T.N. Kirnon School ANB-TNK-01
  • Relatively flat topography
  • Urban location
  • Open windows
ANB-TNK-02
  • Relatively flat topography
  • Urban location
  • Aluminium louvers
Antigua Grammar School ANB-AGS-01
  • Cliff topography
  • Rural location
  • Floor (flooding)
ANB-AGS-02
  • Cliff topography
  • Rural location
  • Floor (flooding)
  • Aluminium louvers
John Hughes Primary School ANB-JHS-01
  • Cliff topography
  • Rural location
  • Breeze block windows
Five Island School ANB-FIS-01
  • Sloped topography
  • Residential rural location
  • Breeze block windows
ANB-FIS-02
  • Relatively flat topography
  • Rural location
  • Breeze block windows
J.T. Ambrose School ANB-JTA-01
  • Relatively flat topography
  • Rural location
  • Aluminium louvers
  • Breeze block windows
ANB-JTA-02
  • Relatively flat topography
  • Rural location
  • Not apparent
ANB-JTA-03
  • Relatively flat topography
  • Rural location
  • Not apparent
Cobbs Cross Primary School ANB-CCS-02
  • Relatively flat topography
  • Residential rural location
  • Breeze block windows
Intrade ANB-INT-01
  • Relatively flat topography
  • Rural location
  • Roof
Holy Trinity School ANB-HTS-01
  • Relatively flat topography
  • Coastal location
  • Breeze block windows
ANB-HTS-02
  • Relatively flat topography
  • Coastal location
  • Aluminium louvers
ANB-HTS-03
  • Relatively flat topography
  • Coastal location
  • Not apparent
Glanvilles Primary School ANB-GPS-01
  • Relatively flat topography
  • Rural location
  • Not apparent
Bendals Primary School ANB-BDS-01
  • Relatively flat topography
  • Rural location
  • Not apparent
Ottos Comprehensive School ANB-OCS-01
  • Relatively flat topography
  • Rural location
  • Not apparent
ANB-OCS-02
  • Relatively flat topography
  • Rural location
  • Breeze block windows

3.3 Vulnerability to Earthquakes

3.3.1 Multi-hazard Design

When compared with dealing with a single hazard, designing against multiple hazards is more than doubly difficult, especially when those hazards are wind and earthquake. Some favourable features of wind-resistant design are unfavourable for earthquake-resistant design and vice versa, eg:

Both hurricanes and earthquakes impose horizontal loads on buildings. Earthquakes also impose significant vertical loads on the overall building. The vertical loading derived from wind is usually significant on parts of a building as determined by aerodynamic considerations.

However, there are many similarities in the effective design and construction of buildings to resist hurricanes and earthquakes:

3.3.2 Differences Between Designing Against Earthquakes and Hurricanes

There is a basic difference in the performance expectations in the event of an earthquake as opposed to a hurricane. A building is expected to survive its "design hurricane" with virtually no damage. Even a catastrophic hurricane should only lead to repairable damage. On the other hand the "design earthquake" is expected to cause (hopefully repairable) damage, and a catastrophic earthquake is likely to lead to a situation where the building cannot be repaired and must be demolished. In such an event success is measured by the absence of deaths and serious injuries.

3.3.3 Aspects of Vulnerability

Designing schools to be safe during earthquakes is a complex process requiring the involvement of specialist structural engineers. In Antigua & Barbuda, as in most parts of the Caribbean, the problem is compounded because of the absence, until very recently, of mandatory earthquake-resistant standards and the lack of a tradition of conscious engineering attention to this subject. Indeed there is no consensus that the hazard is sufficiently serious to warrant concerted action. Thus successes in the area of earthquake-resistant construction tend to be accidental. This comes about principally when the dominant design criterion overrides the demands of earthquake-resistant design.

The main problem areas are summarised below.

3.3.4 Summary of Results

The following table summarises the conclusions of the survey with respect to earthquake vulnerability. A higher Seismic Relative Vulnerability Number indicates a lower vulnerability to seismic events.

Property

Individual Building and Code Number

Structural Members

Vulnerable Areas

Relative Vulnerability Number

Parham Primary School ANB-PPS-01 R.C frame, 8" thick reinforced masonry wall, lightweight roof. Single storey building. ii

2.21

ANB-PPS-02 R.C frame, 8" thick reinforced masonry walls, lightweight roof. Single storey building. ii

0.92

ANB-PPS-03 R.C frame, 8" thick reinforced masonry walls, lightweight roof. Single storey building. ii

0.88

Princess Margaret School ANB-PMS-01 R.C frame, 8" and 6" thick reinforced masonry walls, lightweight roof. Single storey building. ii

1.47

ANB-PMS-02 R.C frame, 6" and 4" thick reinforced masonry walls, lightweight roof. Single storey building. ii

0.69

Liberta Primary School ANB-LPS-01 R.C frame, reinforced masonry walls. Single storey building. ii

0.77

ANB-LPS-02 R.C frame, reinforced masonry walls. Single storey building. ii

0.14

Antigua Girls High School ANB-AGH-01 Structural steel frame and timber walls, lightweight roof. Two-storey building. First storey

0.58

ANB-AGH-02 Structural steel frame and timber walls, lightweight roof. Single storey building. First storey

0.54

Bolans Primary School ANB-BPS-01 R.C frame, 8" and 6" thick reinforced masonry walls, lightweight roof. Single storey building. ii

N/A

ANB-BPS-02 R.C frame, 6" thick reinforced masonry walls, lightweight roof. Single storey building. ii

N/A

Urlings Primary School ANB-UPS-01 R.C frame, 6" thick reinforced masonry walls, lightweight roof. Single storey building. ii

1.27

ANB-UPS-02 Timber structure, lightweight roof. Single storey building. ii

N/A

Greenbay Primary School ANB-GRE-01 R.C frame, 6" thick reinforced masonry walls, lightweight roof. Single storey building. ii

3.36

ANB-GRE-02 R.C frame, 6" thick reinforced masonry ground floor walls and timber first floor walls, lightweight roof. Two-storey building. First storey

0.67

New Winthropes Primary School ANB-NWS-01 R.C frame, 6" thick reinforced masonry walls, lightweight roof. Single storey building. ii

0.40

ANB-NWS-02 Timber structure walls, lightweight roof. Single storey building. ii

N/A

T.N. Kirnon School ANB-TNK-01 Un-reinforced masonry for upper floor and timber structure lower floor, lightweight roof. Two-storey building. First storey and un-reinforced masonry walls

0.27

ANB-TNK-02 R.C frame, 6" thick reinforced masonry walls, heavyweight roof. Single storey building. ii

2.18

Antigua Grammar School ANB-AGS-01 Reinforced masonry walls, lightweight roof. Two-storey building. First storey

0.43

ANB-AGS-02 Reinforced masonry walls, lightweight roof. Two-storey building. First storey

0.80

John Hughes Primary School ANB-JHS-01 Structural steel frame, reinforced masonry walls, lightweight roof. Single storey building ii

0.68

Five Island School ANB-FIS-01 Structural steel frame 6" reinforced masonry walls, lightweight roof. Single storey building ii

1.24

ANB-FIS-02 R.C frame, 6" thick reinforced masonry walls, lightweight roof. Single storey building. ii

2.08

J.T. Ambrose School ANB-JTA-01 Un-reinforced masonry walls, lightweight roof. Single storey building. Un-reinforced masonry walls

0.95

ANB-JTA-02 R.C frame, 6" thick reinforced masonry walls, lightweight building. Single storey building. ii

2.19

ANB-JTA-03 Timber structure, lightweight roof. Single storey building. ii

N/A

Cobbs Cross Primary School ANB-CCS-01 ii ii

0.35

ANB-CCS-02 R.C frame, 6" thick reinforced masonry walls, lightweight building. Single storey building. ii

2.25

Intrade ANB-INT-01 Reinforced and un-reinforced masonry walls, concrete roof. Two-storey building. Un-reinforced masonry walls

0.20

Holy Trinity School ANB-HTS-01 ii ii

1.10

ANB-HTS-02 Un-reinforced masonry walls (stone panels), lightweight roof. Single storey building. Un-reinforced masonry walls

1.60

ANB-HTS-03 R.C frame, reinforced masonry walls, lightweight roof. Single storey building. ii

2.93

Glanvilles Primary School ANB-GPS-01 Structural steel frame, metal panel walls, lightweight roof. Single storey building. ii

0.94

Bendals Primary School ANB-BDS-01 R.C frame, 6" thick masonry walls, lightweight roof. Single storey building. ii

2.13

Ottos Comprehensive School ANB-OCS-01 R.C frame, 8" thick masonry walls, heavy weight roof. Three storey building. First storey

0.11

ANB-OCS-02 R.C frame, 8" thick masonry walls, heavy weight roof. Two-storey building. First storey

0.21

Note 1: The buildings given a grade of N/A are wood buildings for which the method of assessing earthquake vulnerability is not applicable.
Note 2: RC = reinforced concrete
Note 3: ii= Insufficient information provided


4 GENERAL ISSUES

4.1 Impact of Hurricanes on Caribbean Schools

Hurricanes David in 1979, Allen in 1980, Hugo in 1989 and Luis in 1995 caused significant damage to schools in Dominica, St. Lucia, Montserrat and Antigua respectively. The review of the damage to most of the schools showed that roof failure was the primary cause of problems, leading in some cases to complete collapse of the walls. Most of the roofs were made of wooden rafters or trusses with 26-gauge (or thinner) galvanised sheeting. Few roofs of aluminium sheeting survived. Some roofs remained partially intact but the damage to windows, doors and internal partitions was significant. Some wooden structures were completely destroyed, sometimes by falling trees and sometimes by being blown off their foundations.

In general, therefore, the response of the school buildings to hurricane forces must be judged to have been poor. It is disturbing to note that the reconstruction of many of the schools which suffered from the recent hurricanes and the construction of some new schools have been based on the same design concepts which have led to the failures.

4.2 Hazards versus Disasters

Disasters are often seen as unpredictable, having to do with luck and part of the risks of everyday living. Surely we have progressed beyond the stage when superstition, mythology and fatalism were the public responses to natural hazards. Hurricanes are not natural disasters, they are natural events which sometimes lead to manmade disasters. In these days of widespread technological education, sophisticated research, reliable building materials, computer-based geographical information systems and satellite-assisted warning programmes, hurricanes in the Caribbean should not lead to disasters. The one exception to this would be vulnerable agricultural crops such as bananas.

It is now evident that disasters due to natural hazards are largely preventable and soon the public will demand deliberate actions to protect communities against hazardous events.

4.3 Codes and Standards

The development and maintenance of building standards and codes is a continuing process in many countries. The mandate of national or regional professional and governmental institutions usually includes the development of building standards and the co-ordination of such activities among its various constituent members.

To date the majority of countries in the Caribbean region are without satisfactory, mandatory standards dealing adequately with any of the prevalent natural hazards. In 1996, Antigua and Barbuda passed regulations to the 1974 Development Control Act mandating the use of the Antigua and Barbuda Building Code. These regulations give firm authority to the Development Control Authority to require all developments to be designed and constructed in accordance with the Building Code and the companion Building Guidelines. To date, regulating the use of the Code appears to be a problem.

4.4 The Regulatory Environment

Some government agencies adopt an ad hoc approach to standards based, principally, on the particular individuals involved in the specific projects. In most cases the administrators tacitly assume that their designers and builders would do what is right without being told. In other cases the administrators adopt the approach of not objecting to safe design and construction, provided that these attributes do not interfere with their other aims for the projects.

Many government capital works projects are funded by international lending agencies. Typically there is reluctance on the part of these agencies to impose structural design criteria on their projects. The funding agencies leave it up to the governments and the governments leave it up to their designers and builders. This laissez-faire approach leads to inconsistent performance, lack of reliability and, arguably, to higher overall life-cycle costs for the built environment.

The Antigua and Barbuda Building Code has been adopted formally by the Government. This is a significant step in the right direction.

The enforcement of the code is now the critical function to be performed. The system of check consultants (bureaux de contrôle), routinely used in French territories, is proposed. Check consultants are independent of the design consultants. It is well recognised that quality assurance is more effective where checking is done independently of creating. The system mentioned above formalises the process.

4.5 Public Awareness

During the past 111 years a total of approximately 1000 tropical storms and hurricanes have been recorded over the North Atlantic area. Of these, about 50 percent were hurricanes, many in the general area of the Caribbean. With such a record, it is not surprising that everyone in this region accepts that hurricanes are a fact of life. However, the frequency of direct hits by hurricanes on any one territory is low. This has led to a considerable lack of consciousness amongst Caribbean people as to the dangerous risk to their own properties. Few believe that their island would be hit.

In the post-Columbian history of Antigua and Barbuda there have been 44 recorded hurricane events that have affected these islands. Not all of these were direct hits by hurricane-force winds. In many cases the effects were by way of heavy seas and torrential rain. The most recent of these events were hurricanes Hugo (1989), Luis (1995) and Marilyn (1995). Hugo and Marilyn did not produce more than minimum hurricane winds. However, Luis was a major hurricane event in Antigua and Barbuda.

4.6 Vulnerability Surveys

4.6.1 Qualitative Assessment

This is the level of assessment being carried out in the present programme. This level of evaluation does not envisage exhaustive testing of materials in place nor sophisticated computation of stresses. It does involve a careful review of all readily available data (such as drawings), an inspection of the building without destructive testing and a non-mathematical review of the data.

4.6.2 Analytical Evaluation

Facilities whose performances are deemed to be doubtful when assessed qualitatively would be subjected to an analytical evaluation. This procedure would also be used as a second stage, prior to implementation of retrofitting, in cases deemed to be self-evidently inadequate by qualitative assessment. Since analytical evaluation is a time-consuming and expensive exercise it would be appropriate to carry it out only when the funds were available for implementing the possible actions indicated by such evaluation.

It is envisaged that analytical evaluations will be undertaken for those schools selected for the CDB retrofit project.

4.7 Disaster Mitigation after the Event

In the aftermath of a disaster the focus is understandably on getting educational facilities to function again as soon as possible. Also, technical personnel and financial resources are spread very thin at such times. This combination of factors often leads to repairs being carried out in an expedient manner without adequate attention to safety issues. Indeed, post-disaster repairs often leave the buildings even more vulnerable than they were in their pre-disaster, inadequate states.

If such a scenario is to be avoided, the custodians of the educational facilities must take very deliberate steps. Such actions would include:

4.8 Maintenance as a Tool for Mitigation

The physical condition of many Caribbean schools is poor. Windows and doors show lack of maintenance and repair. It is considered that a major effort should be taken to bring the condition of the buildings to the standard where a normal maintenance crew can be expected to deal with the routine maintenance requirements of the facility. It is considered, also, that the existing staff and maintenance budget are generally insufficient to provide for proper maintenance.

It is recommended that for public buildings with the heavy use of a school, the annual maintenance budget should amount to about 4% of the contemporary capital cost of the building and equipment, assuming that the facilities are in good condition to start with. For schools, it is estimated that the replacement cost is about US$150,000 per classroom. (This figure includes amounts for common and administrative areas as well as infrastructure.) The maintenance allocation should therefore be no less than US$6,000 per classroom per year.

The maintenance of a school, rather than being a one-time activity as is the construction of the school, is a continuous daily operation of the institution and is an important ingredient in the delivery of education.

A good maintenance system is also a good disaster mitigation system, as the review of damage caused by recent hurricanes and floods has shown. To some extent the damage to buildings was due to lack of sustained maintenance of critical items. Also, a well operated system of maintenance for buildings and equipment has the effect of being a very effective disaster mitigation measure in terms of cost and facility usage. It ensures the most economic way to keep the building and equipment in the best of form for normal use, given the original design and materials. It is essential that a maintenance plan be included in disaster mitigation plans.

It should be noted that the establishment of a secure and orderly system of archiving of construction drawings depicting the as-built condition of the final structure is an essential ingredient of the long-term maintenance schedule of any constructed facility. Because the archive will serve its purpose over the lifetime of the facility, the protection of its contents against the effects of time cannot be overlooked.


5 HURRICANES LUIS AND MARILYN IN ANTIGUA AND BARBUDA

5.1 Damage and Repairs

As a result of hurricanes Luis and Marilyn in 1995, the following general damage to the school buildings was reported:

It should be noted that some schools not on the present list were completely destroyed by hurricane Luis.

Most of the buildings on the present list have been subsequently repaired. The damage and repairs are described in the following table.

Property

Individual Building and Code Number

Description of Damage

Repairs and Reconstruction

Parham Primary School ANB-PPS-01
  • Loss of roof over shed.
  • Minor damage to eaves of one block.
  • General maintenance and replacement of roof.
  • ANB-PPS-02
    • Roof of walkway destroyed.
  • General repairs.
  • ANB-PPS-03
    • Damage to roof (partial).
  • Replacement of damaged roof.
  • Princess Margaret School ANB-PMS-01
    • Some roof damage.
  • Replacement of roof.
  • ANB-PMS-02
    • Partial loss of roof and loss of windows.
  • Replacement of asbestos roofing with metal profile sheets.
  • Liberta Primary School ANB-LPS-01
    • N/A
  • Unknown
  • ANB-LPS-02
    • N/A
  • Unknown
  • Antigua Girls High School ANB-AGH-01
    • Partial loss of roof to main building, and damage two windows.
  • Roof covering was replaced after hurricane.
  • ANB-AGH-02
    • Windows were dislocated during hurricane.
    • Partial loss of roof.
  • Replacement of windows, ceiling, roofs cladding electrical fixture.
  • Bolans Primary School ANB-BPS-01
    • Flooding due to rising groundwater.
    • Damage to doors and windows.
    • Loss of guttering.
  • Unknown
  • ANB-BPS-02
    • Flooding due to rising groundwater.
    • Damage to doors and windows.
    • Loss of guttering.
  • Unknown
  • Urlings Primary School ANB-UPS-01
    • Partial loss of roof to administrative block and classroom (north).
  • Replacement of roofing materials.
  • ANB-UPS-02
    • Loss of roof metal sheets.
  • Repair work to roof.
  • Greenbay Primary School ANB-GRE-01
    • Total loss of both sheeting and structure.
    • Parapet to upper floor of main block was torn off.
    • Vertical RC supports were cracked and spalling.
  • Repairs of damages scheduled into general maintenance.
  • Improvement regarding the shape and slope of roof was made.
  • ANB-GRE-02
    • Loss of the veranda (covered walkways).
  • Hurricane straps were included in reconstruction.
  • New Winthropes Primary School ANB-NWS-01
    • None
  • General maintenance only.
  • ANB-NWS-02
    • None
  • None
  • T.N. Kirnon School ANB-TNK-01
    • Minimal damage except for balcony roof which was lost.
  • General maintenance only.
  • ANB-TNK-02
    • None
  • General maintenance only.
  • Antigua Grammar School ANB-AGS-01
    • Loss of canopy over entrance.
    • Loss of metal roof sheeting (5-10%).
    • Flooding due to loss of roof.
  • Replacement of metal sheeting.
  • ANB-AGS-02
    • Loss of windows.
    • Damage to porch roof.
    • Loss of roof metal sheeting.
  • Reconstruction of structure.
  • John Hughes Primary School ANB-JHS-01
    • N/A
  • Unknown
  • Five Island School ANB-FIS-01
    • Loss of roof.
  • Unknown
  • ANB-FIS-02
    • Loss of roof and windows.
  • Replacement of roof structure and sheeting.
  • J.T. Ambrose School ANB-JTA-01
    • Loss entire roof (main hall).
  • Repair roof.
  • ANB-JTA-02
    • Major roof damage.
  • Unknown
  • ANB-JTA-03
    • Major roof damage.
  • Unknown
  • Cobbs Cross Primary School ANB-CCS-02
    • Partial roof damage ton walkways.
    • Timber roof was entirely destroyed.
  • General maintenance.
  • Intrade ANB-INT-01
    • Loss of roof in the middle section.
  • Unknown
  • Holy Trinity School ANB-HTS-01
    • Shed roof was lost (water cistern).
  • Unknown
  • ANB-HTS-02
    • Extensive roof and ceiling damages.
    • Rain water guttering destroyed.
  • Unknown
  • ANB-HTS-03
    • Total loss of roof.
  • Unknown
  • Glanvilles Primary School ANB-GPS-01
    • Rotted cladding was torn away.
    • Upturned ceiling tore off.
  • Unknown
  • Bendals Primary School ANB-BDS-01
    • Loss of walkway canopy.
    • Partial loss of roof.
  • Replacement of lost sheeting.
  • Ottos Compre-hensive School ANB-OCS-01
    • Loss of some windows, doors and shutters.
  • Replacement of all doors.
  • Repair to windows and shutters.
  • ANB-OCS-02
    • Loss of some windows, doors and shutters.
  • Replacement of windows and all doors.
  • The standards used for the reconstruction activities, with respect to wind and earthquakes, are unknown.

    5.2 Recommendations

    The following recommendations are made with a view to reducing the vulnerability of the buildings surveyed to hurricanes, torrential rains, and earthquakes. The activities required are generally:

    1. Protect glass windows and doors with approved shutters.
    2. Stop the rainwater ingress through breeze block windows by installing shutters.
    3. Secure the timber shutters at the corners by installing bolts.
    4. Improve timber roof framing connections by installing approved hurricane straps and ties.
    5. Improve the roof sheeting connections by installing additional screws in vulnerable roof areas.
    6. Improve the water tightness of the aluminium louver windows.
    7. Strengthen un-reinforced masonry walls.
    8. Improve the drainage around the property.

    If these recommendations are carried out, then all of the properties surveyed can be used as shelters, however it may be prohibitively expensive to install a new roof and strengthen the un-reinforced walls of Intrade. It may also be relatively expensive to provide adequate drainage around the low-lying Antigua Girls High School. It may therefore be appropriate to exclude the Intrade building and this school from further consideration as shelters.

    The following table summarises the recommendations for each property.

    Property

    Individual Building and Code Number

    Recommendations

    Parham Primary School ANB-PPS-01
    • Improve site drainage.
    • Install additional screws in vulnerable roof areas.
    • Improve timber roof framing connections.
    • Provide shutters to cover the breeze blocks.
    ANB-PPS-02
    • Improve site drainage.
    • Install additional screws in vulnerable roof areas.
    • Improve timber roof framing connections.
    • Provide shutters to cover the breeze blocks.
    ANB-PPS-03
    • Improve site drainage.
    • Install additional screws in vulnerable roof areas.
    • Provide shutters to cover the breeze blocks.
    Princess Margaret School ANB-PMS-01
    • Improve site drainage.
    • Install additional screws in vulnerable roof areas.
    • Improve timber roof framing connections.
    • Provide shutters to cover the breeze blocks.
    • Protect glass windows.
    • Improve water tightness of aluminium louvers.
    ANB-PMS-02
    • Improve site drainage.
    • Install additional screws in vulnerable roof areas.
    • Improve timber roof framing connections.
    • Provide shutters to cover the breeze blocks.
    • Protect glass windows.
    • Improve water tightness of aluminium louvers.
    Liberta Primary School ANB-LPS-01
    • Install additional screws in vulnerable roof areas.
    • Improve timber roof framing connections.
    • Provide shutters to cover the breeze blocks.
    • Secure timber shutters.
    ANB-LPS-02
    • Install additional screws in vulnerable roof areas.
    • Improve timber roof framing connections.
    • Provide shutters to cover the breeze blocks.
    • Secure timber shutters.
    Antigua Girls High School ANB-AGH-01
    • Improve site drainage.
    • Install additional screws in vulnerable roof areas.
    • Improve timber roof framing connections.
    • Provide shutters to cover the breeze blocks.
    • Protect glass windows.
    • Improve water tightness of aluminium louvers.
    • Secure timber shutters.
    ANB-AGH-02
    • Improve site drainage.
    • Install additional screws in vulnerable roof areas.
    • Improve timber roof framing connections.
    • Provide shutters to cover the breeze blocks.
    • Protect glass windows.
    • Improve water tightness of aluminium louvers.
    • Secure timber shutters.
    Bolans Primary School ANB-BPS-01
    • Improve site drainage.
    • Install additional screws in vulnerable roof areas.
    • Improve timber roof framing connections.
    • Provide shutters to cover the breeze blocks.
    • Improve water tightness of aluminium louvers.
    ANB-BPS-02
    • Improve site drainage.
    • Install additional screws in vulnerable roof areas.
    • Improve timber roof framing connections.
    • Provide shutters to cover the breeze blocks.
    • Improve water tightness of aluminium louvers.
    Urlings Primary School ANB-UPS-01
    • Install additional screws in vulnerable roof areas.
    • Improve water tightness of aluminium louvers.
    ANB-UPS-02
    • Install additional screws in vulnerable roof areas.
    Greenbay Primary School ANB-GRE-01
    • Install additional screws in vulnerable roof areas.
    • Provide shutters to cover the breeze blocks.
    • Improve water tightness of aluminium louvers.
    ANB-GRE-02
    • Install additional screws in vulnerable roof areas.
    • Improve water tightness of aluminium louvers.
    New Winthropes Primary School ANB-NWS-01
    • Improve site drainage.
    • Install additional screws in vulnerable roof areas.
    • Improve timber roof framing connections.
    • Strengthen un-reinforced stone masonry walls.
    • Repair cracked columns.
    • Provide shutters to cover the breeze blocks.
    • Install shutters over open windows.
    ANB-NWS-02
    • Improve site drainage.
    • Install additional screws in vulnerable roof areas.
    • Improve timber roof framing connections.
    • Strengthen un-reinforced wall.
    • Install shutters over open windows.
    T.N. Kirnon School ANB-TNK-01
    • Install additional screws in vulnerable roof areas.
    • Improve timber roof framing connections.
    • Strengthen un-reinforced wall.
    • Install shutters over open windows.
    ANB-TNK-02
    • Install additional screws in vulnerable roof areas.
    • Improve timber roof framing connections.
    • Improve water tightness of aluminium louvers.
    Antigua Grammar School ANB-AGS-01
    • Improve site drainage.
    • Install additional screws in vulnerable roof areas.
    • Improve timber roof framing connections.
    • Strengthen un-reinforced wall.
    • Protect glass windows.
    ANB-AGS-02
    • Improve site drainage.
    • Install additional screws in vulnerable roof areas.
    • Improve timber roof framing connections.
    • Improve water tightness of aluminium louvers.
    John Hughes Primary School ANB-JHS-01
    • Install additional screws in vulnerable roof areas.
    • Provide shutters to cover the breeze blocks.
    Five Island School ANB-FIS-01
    • Install additional screws in vulnerable roof areas.
    • Provide shutters to cover the breeze blocks.
    ANB-FIS-02
    • Install additional screws in vulnerable roof areas.
    • Provide shutters to cover the breeze blocks.
    J.T. Ambrose School ANB-JTA-01
    • Install additional screws in vulnerable roof areas.
    • Improve timber roof framing connections.
    • Provide shutters to cover the breeze blocks.
    • Improve water tightness of aluminium louvers.
    ANB-JTA-02
    • Install additional screws in vulnerable roof areas.
    ANB-JTA-03
    • Install additional screws in vulnerable roof areas.
    Cobbs Cross Primary School ANB-CCS-02
    • Provide shutters to cover the breeze blocks.
    Intrade ANB-INT-01
    • Construct new roof.
    • Protect glass windows and doors.
    • Strengthen un-reinforced masonry walls.
    Holy Trinity School ANB-HTS-01
    • Install additional screws in vulnerable roof areas.
    • Improve timber roof framing connections.
    • Provide shutters to cover the breeze blocks.
    ANB-HTS-02
    • Install additional screws in vulnerable roof areas.
    • Improve timber roof framing connections.
    • Strengthen un-reinforced masonry walls.
    • Improve water tightness of aluminium louvers.
    ANB-HTS-03
    • Install additional screws in vulnerable roof areas.
    • Improve timber roof framing connections.
    Glanvilles Primary School ANB-GPS-01
    • Install additional screws in vulnerable roof areas.
    Bendals Primary School ANB-BDS-01
    • Install additional screws in vulnerable roof areas.
    Ottos Comprehensive School ANB-OCS-01
    • Repair and protect glass windows.
    ANB-OCS-02
    • Provide shutters to cover the breeze blocks.

    5.3 Classes of Vulnerability

    From the mitigating measures described in Section 5.2, several classes of vulnerability are identified. They are:

    The following table identifies the vulnerable classes for each property.

    Property

    Individual Building and Code Number

    Vulnerable Roof

    Vulnerable Walls

    Vulnerable Openings

    Vulnerable Drainage

    Parham Primary School ANB-PPS-01

    a

     

    a

    a

    ANB-PPS-02

    a

     

    a

    a

    ANB-PPS-03

    a

     

    a

    a

    Princess Margaret School ANB-PMS-01

    a

     

    a

    a

    ANB-PMS-02

    a

     

    a

    a

    Liberta Primary School ANB-LPS-01

    a

     

    a

     
    ANB-LPS-02

    a

     

    a

     
    Antigua Girls High School ANB-AGH-01

    a

     

    a

    a

    ANB-AGH-02

    a

     

    a

    a

    Bolans Primary School ANB-BPS-01

    a

     

    a

    a

    ANB-BPS-02

    a

     

    a

    a

    Urlings Primary School ANB-UPS-01

    a

     

    a

     
    ANB-UPS-02

    a

     

    a

     
    Greenbay Primary School ANB-GRE-01

    a

     

    a

     
    ANB-GRE-02

    a

     

    a

     
    New Winthropes Primary School ANB-NWS-01

    a

    a

    a

    a

    ANB-NWS-02

    a

    a

    a

    a

    T.N. Kirnon School ANB-TNK-01

    a

    a

    a

     
    ANB-TNK-02

    a

     

    a

     
    Antigua Grammar School ANB-AGS-01

    a

    a

    a

    a

    ANB-AGS-02

    a

     

    a

    a

    John Hughes Primary School ANB-JHS-01

    a

     

    a

     
    Five Island School ANB-FIS-01

    a

     

    a

     
    ANB-FIS-02

    a

     

    a

     
    J.T. Ambrose School ANB-JTA-01

    a

     

    a

     
    ANB-JTA-02

    a

         
    ANB-JTA-03

    a

         
    Cobbs Cross Primary School ANB-CCS-02    

    a

     
    Intrade ANB-INT-01

    a

    a

    a

     
    Holy Trinity School ANB-HTS-01

    a

     

    a

     
    ANB-HTS-02

    a

    a

    a

     
    ANB-HTS-03

    a

         
    Glanvilles Primary School ANB-GPS-01

    a

         
    Bendals Primary School ANB-BDS-01

    a

         
    Ottos Comprehensive School ANB-OCS-01    

    a

     
    ANB-OCS-02    

    a

     

    5.4 Further Work

    The intent of this report is to classify the surveyed properties with respect to their vulnerable areas, and hence retrofit needs. This has been done. The next step is to provide global cost estimates for performing the retrofit tasks. This will be done in a subsequent report.


    REFERENCES

    1. Caribbean Disaster Mitigation Project funded by the United States Agency for International Development (USAID) and managed by the OAS
    2. European Community Humanitarian Office
    3. Insurance Institute for Property Loss Reduction
    4. International Development Research Centre, Ottawa, Canada
    5. 1000 gals is approximately equal to the acceleration due to gravity
    6. This is part of the OECS Building Code project funded by the United Nations Development Programme (UNDP) through the United Nations Centre for Human Settlements (UNCHS) or Habitat.
    7. kPa = kilopascals
    8. metres per second
    9. Seismic Vulnerability Assessment of Low-Rise Buildings in Regions with Infrequent Earthquakes by Ahmed F Hassan and Mete A Sozen, ACI Structural Journal, January-February 1997, pages 31 et seq