by Mohammed Azad Hossain

Building components tend to fail depending on materials, designs, method of construction, environmental conditions and the use to which the building is put. Substandard materials and design errors are major causes of component failure.

Some of the main causes for building collapses are bad design, faulty construction, foundation failure, extraordinary loads, unexpected failure modes or a combination of causes. But collapses also occur due to natural disasters such as earthquakes, floods, hurricanes, cyclones and fires.

Common design faults

All structures are designed to support loads without deforming excessively. These loads include live load, which is the weight of people and objects, rain and wind, and the dead load of the building itself.

Internal factors/human errors

The internal factors for bad design don’t only mean errors of computation, but a failure to account for loads the structure will be expected 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. The structural engineer is responsible for these failures, which are created at the drawing board. Sometimes failures occur due to obvious negligence or gross human error.

The external factors

These are often natural, such as extraordinary loads, heavy rain, earthquakes, hurricanes and a defective site, with very unusual ground conditions, like sinking holes or swampy land. A building that is intended to stand for some years should be able to meet all these challenges. This is incorporated into the design. Identification of the characteristics of particular site conditions by the engineers/consultants, through suitable geo technical studies, can help with site selection and site progress that reduce the risk of failure.

Inadequate awareness

Many structural failures have been the consequence of poor technical research and knowledge. As technical awareness gets better, errors are becoming by far the major cause of known structural collapses, mainly in technologically advanced countries. An error in this situation is a gross error or mistake, not a negligible computation error or construction divergence.

Common construction faults

Inappropriate construction

The contractor’s failure to build in accordance with drawings and specifications can also add to failure of structures. Use of inferior or sub-standard building materials is another reason buildings fail. Overloading during the life span of a building can critically weaken the structural reliability of it. Extra loads due to unauthorised change of use or additions and alterations to the structure can intensify an under-designed building and can contribute to its eventual failure.

Performance failures

Performance failure can be described as an intolerable difference between anticipated and existing design and construction. The engineer’s design interpretation must be put aside at the construction stage for the structure to be effectively constructed.

Failure may occur due to consultants’ and contractors’ inadequate supervision and control of site operations and quality control. Such errors ultimately lead to a situation, which may involve such failures, which are related to excavation and equipment, inappropriate sequencing, not enough temporary support; unnecessary structure weight; untimely taking away of shoring or formwork; and non conformance to design objectives.

Common material faults

Most structural failures are associated with materials and are the consequence of human error involving a lack of knowledge about materials or the combination of contrary materials. There are structural failures that can be endorsed to irregularity in materials. Although much reliance is given on modern structural materials, the manufacturing or production faults may exist even in the most dependable structural materials, such as standard structural steel. Stone frontage sheets or glass curtain walls may have hidden serious faults.

Prevention

Most of the structural failures (other than those caused by natural disasters) have occurred due to such faults, which are controllable. Good operational planning and detailed deliberations can save the failures of the valuable structures. The well-designed structures, coupled with the hard effort of the experts and correct materials can ensure the structure a complete success. Some other important points of failure prevention are:

Professionalism

It is of extreme significance for building professionals, including builders and government bodies, to understand that the design process does not stop at the conclusion of design drawings and specifications. The design aim must take second place in the construction stage.

Increased antagonism during construction bidding, along with developers’ aim of profit making, can place intense pressure and demand on the engineers/consultants to create the most inexpensive and efficient design. However, this should not compromise safety. Building experts have a great liability to make sure that the safety of the buildings and infrastructures is to the maximum.

Statutory bodies should be more proactive in imposing strict regulations in building design, codes and standards and impose penalties for the violators.

Integrated efforts by all parties

Consultants and contractors must have total control of site operations and quality. Site staff are required to be well qualified and competent and correctly trained in the trade in which they are working to ensure good workmanship and high quality of building works. Independent inspections by statutory bodies are essential to make sure that the building is constructed in accordance with approved plans and specifications.

A check system must be utilised to assess the integrity of structures based on the professional engineer’s design and to give independent design results to ascertain the sufficiency of the major structural rudiments of the buildings.

The recognised check should therefore give particular concentration to unusual design details. The inspector and checker should concentrate on significant areas such as transfer beams and columns, and the centre of attention should be kept on areas where errors are critical and frequent.

Conclusion

Design is a human endeavor and thus it is subject to error. Due to this, some designs are destined to fail.

In case of a building failure there must be a transparent investigation with professional engineers and forensic experts experienced in identifying the root cause of failure. And having found the possible causes of the failure, it is vital to know how to avoid it in the future. The primary step in preventing building failures is to develop a programme for educating all parties on lessons learnt from past failures. It is not advisable that a mistake once committed and affected is repeated.

CW

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