World Trade Centre Disaster: Building Performance

The World Trade Centre buildings (WTC-1 and WTC-2) were 110-story towers located in New York. On the

morning of September 11, 2001, two hijacked commercial jetliners were deliberately flown into the WTC towers,

which resulted in the collapse of these towers. These events were among the worst man-made building disasters

and loss of life from any single building event. Over 3000 people lost their lives that day at the World Trade

Center (WTC) site, including 343 emergency responders. The world was shocked by the attacks and resulting

collapse of office buildings that had been in use everyday. This article briefly presents observations, findings,

and recommendations regarding the performance of World Trade Centre towers (WTC-1 and WTC-2). It also

describes the structural and fire protection features of these two towers and their performances in response to

the terrorist attacks. The ability of the two towers to withstand aircraft impacts without immediate collapse as

long as they did, and allow the evacuation of most building occupants was admirable. Studies should be

conducted determine, given the great size and weight of the towers, whether there are feasible design and

construction features that would permit such buildings to arrest or limit a collapse, once it began.

INTRODUCTION

Civil Engineering, which is one of the oldest professions, is a broad engineering field. Civil engineers

provide modern society with vital infrastructure and lifeline systems such as cities, roads, buildings, bridges,

railroads, water systems, etc. In addition, they protect society from extreme forces of nature such as high winds,

earthquakes and floods. Civil engineers design, build and manage water resources, and waste water treatment

facilities. Civil engineering includes environmental engineering aspects. Transportation engineers and

geotechnical engineers are civil engineering graduates. Structural design and construction constitutes a major

component of civil engineering related activities. The civil engineering program at McMaster University provides

specialization in two areas, namely Structures and Geotechnical Engineering Stream, and Water and

Environmental Engineering Stream.

By far the largest percentage of structures inventory worldwide is buildings. Similarly, the largest

percentage of structures under construction is buildings. "Building" means any structure used or intended for

supporting or sheltering any use or occupancy. In Canada, all buildings must satisfy the National Building Code

requirements. (NBCC, 2005, NFC, 2005) NBC is essentially a code of minimum regulations for public health, fire

safety and structural sufficiency with respect to the public interest. It establishes a standard of safety for the

construction of buildings, including extensions or alterations, the evaluation of buildings undergoing a change of

occupancy and upgrading of buildings to remove an acceptable hazard. National Fire code is a model set of

technical requirements designed to provide an acceptable level of fire protection and prevention within a

community. It establishes a satisfactory standard for fire prevention, fire fighting, and life safety in buildings in

use, including standards for the conduct of activities causing fire hazard, maintenance of fire safety equipment

and egress facilities, standards for portable extinguishers, limitations on building contents and the establishment

of fire safety plans, including the organization of supervisory staff for emergency purposes. In this sense, a

special relationship exists between the National Building Code and the National Fire Code.

As indicated, building design and occupancy is governed by building codes that specify the minimum

environmental