The Collapse of Buildings

The Collapse of Buildings

Posted By: Blue Print Blog on 17th of October 2013

Buildings, like all structures are designed with special attention to allow the support certain loads without deforming. The loads that are taken into account during the design stage of any building include both live loads and dead loads like furniture and equipment. For a building to be declared safe for occupation it must be able to withstand the weight of rain and the pressure of wind as well as bear the load of the building itself. Buildings that comprise fewer floors, strength generally accompanies sufficient rigidity and the design is mainly that of a roof that will keep the weather out while spanning large open spaces. With tall buildings that consists of several floors the roof becomes a minor matter and the support of the weight of the building itself should be the main consideration since just like long bridges, tall buildings are subject to catastrophic collapse if considerable care is not taken during the design stage. The main causes of collapse in buildings can be generally classified under the following; Bad Design Faulty Construction Foundation Failure Extraordinary Loads Bad Design Bad design due to errors of computation and failure to take into account the loads the structure will be called upon to carry, erroneous theories, reliance on inaccurate data, ignorance of the effects of repeated or impulsive stresses, and improper choice of materials or misunderstanding of their properties may easily result into a collapse of the building. The engineer should take a keen interest during the design stage as he is bound to be held responsible in the event of these failures. Faulty construction Faulty construction has been the most often cause in recurrence of structural failure. This may occur due to mistakes arising from lax in inspection which includes the use of salty sand during concrete mixing, the substitution of inferior steel for that specified, bad riveting or even improper tightening of nuts, bad welds, and other practices well known to the construction worker. Foundation Failure Even an excellently designed and constructed structure will not stand on a bad foundation. Although the structure will carry its loads, the earth beneath it may not. The Leaning Tower of Pisa is a famous example of bad foundations but it is not the only one. The old armory in St. Paul, Minnesota, sank 20 feet or more into soft clay, but did not collapse. The displacements due to bad foundations may alter the stress distribution upon the building significantly. Extraordinary Loads Extraordinary loads are often natural, such as repeated heavy snowfalls, or the shaking of an earthquake, or the winds of a hurricane. A building that is intended to stand for some years should be able to meet the challenges of extraordinary load that may arise from frequent earthquakes and strong winds. Even a solid masonry building would be destroyed in an event of earthquakes if the foundation is not designed carefully to withstand external natural strains.