Structural Engineering

Possible causes of Structural failure

Structural Engineering is a subset of civil engineering, where structural engineers are trained on how to design the “bones and muscles” that make the actual form and structure of man-made structures. This type of engineering has very high standards in what it takes to build commercial and residential buildings as well as structures for the military. There are many areas that fall under the category of structural engineering. These include structural steel, reinforced concrete, column line steel, masonry, piping, interior support, doors, window panes, roofing, walls, and earthquake response.

The field of structural engineering has many uses. One of the most popular of these uses is the construction and design of bridges. Bridges are one of the most important pieces of road building and transportation. A quality structural engineer can help determine the proper specifications for a structure, which will make the structure able to withstand any weather condition. According to Allen Fiford, Director at AF Consulting Engineers & Associates, specifications often refers to a set of documented requirements to be satisfied by a material, design, product, or service. When specifications are provided by a Structural Engineer, it is often a type of technical standard. “There are different types of technical or engineering specifications and the term is used differently in different technical contexts,” he elaborates.

“A Specification is basically a document that describes the scope of work, the type of materials to be used, the quality of workmanship and the methodology of installation in a specific contract. This is to be used and read in conjunction with contract construction drawings. The specification is a living document to be used by the project team during the construction phase; its value does not terminate at the design phase,” defines Eng. Gibson N. Wanjau, Director & Principal Engineer at EL ARCA Engineering.

To the best of his knowledge, Eng. Wanjau further points out the proper Specifications for a Structure should; 1. Clearly define the Materials and manufacturers’ items to be used on site 2. Back up the cost of the project, not only the materials and products but also the performance and workmanship of the contractor. 3. Identify installation, testing and handover requirements. 4. Be clear, and rich in information to provide answers to the many construction questions on site, saving the project team, contractor and client time and money 5. Assist in minimizing project risk and providing support should there be any legal disagreements. 6. Reference the quality and standards which should be applied on a construction project. Structural engineer also ensures that all the necessary tests are passed before any construction project is put into use. Another application of structural engineering deals with the prevention of structural failure. All structures, including buildings, have the potential for failure at some point. This is when the effects of stress are greatest. The primary reason for structural failure is the rate of change of a structure’s loadbearing capacity and load distribution. For example, if a heavy load is placed on a weak point, the structure can experience structural failure. If the load changes, the strength of the structure can decrease or the force by which the structure compresses or grows can change, affecting the performance of the structure.

However, Allen believes that, in the construction industry or build environment, defective construction which causes failure may be caused due to numerous/several reasons that may not be easy to predict before or during the construction of a project. The major causes of structural failure are defective designs that have not determined the actual loading conditions on the structural elements. Inferior construction materials may also be the cause since

the loads are calculated for materials of specific characteristics. Structures may fail even if the design is satisfactory, but the materials are not able to withstand the loads.

“We at AF Consulting Engineers & Associates have witnessed in many scenarios where employment of unskilled labour in construction work becomes a huge problem, this is another reason for why we witness structural failures. Hence the reason why it is so important to appoint reputable professionals to educate, designers builders, homeowner builder’s… etc., to make each party fully conscious of the reasons why structures fail, and undertake all preventive measures preventing structures from failing,” he recommends.

Conforming to Allen, failures occurs very rarely as a result to inadequate design, more often because of bad construction practice, either due to ignorance or cutting corners for profit. "This is where supervision comes in and therefore our fees as professionals should be respected," he concludes.

“Structural elements tend to fail because of use of substandard materials, error in Structural designs, the methodology of construction, external/environmental conditions and the usage to which the building is put,” says Eng. Wanjau. He supplementary expand on possible causes of structural failure;

1. Use of Substandard

Materials and Lack of quality control

This happens when the contractor/builder decides to use inferior materials to put up the structure. E.g., Use of the wrong mix ratio of concrete (of lower class than specified). Failure may also occur due to contractor and Engineer’s inadequate supervision and control of operations and material quality.

2. Methodology of Construction The contractor’s failure to construct in accordance with drawings and specifications given by the engineer can also be a cause or reason for failure of structures.

3. External/Environmental Conditions

These are often natural, such as unexpected loads, heavy rain, earthquakes and maybe defective sites, which may have unusual ground conditions e.g., sinking holes or even swampy land.

4. Error in Structural designs

Error in design don’t only mean errors of computation, but also it can be a failure to account for loads the structure will be expected to carry, reliance on inaccurate data and improper choice of materials and their properties.

5. The Structure Usage

Every structure is designed and built to withstand a certain amount load. A residential house is designed to withhold the weight of the residents living in it. If the same building is used as a warehouse, then that structure stands at a risk of being overstressed.

Structural engineers perform an assortment of tasks within a building. Many of these engineers will be involved in the planning process, which will

determine many of the building’s characteristics. They will be responsible for determining the structural integrity, load bearing ability, and conditions of the structure, among other things. Structural engineers can also implement many of the building’s controls, ensuring that they work correctly, and can monitor the overall effectiveness of the facility.

Many construction projects in earthquakes zones require the help of structural engineering. In addition to assisting in the planning and execution of the project, structural engineers must ensure that the integrity of the buildings is not compromised. They perform tests on beams and walls, as well as check for weak areas. In many cases, structural engineers must also rebuild the entire project of the facility Civil engineers may also be called upon during a large earthquake to inspect any damaged areas and ensure that safety regulations have been followed. Many smaller civil engineering firms specialize in a particular segment of the field. Some specialize in projects that focus on the residential market, while others focus on commercial projects such as apartment complexes and office buildings. Structural engineers may choose to work on either a specialty or multi-specialty basis, depending on the type of structure they are working on. Whatever the case, it is almost certain that structural engineering will continue to grow in importance as time goes by.

AF Consulting Engineers & Associates is a company that is an independent multi-disciplinary consultancy firm providing engineering services for the built environment. We are a company that builds its stature in building partnership through trust, commitment and standing together with honour with leading companies in the Construction Industry.

Do You Have A Construction Project We Can Help With? Contuct Us:

Email: allen@afconsultingeng.co.za info@afconsultingeng.co.za Address: 109 Komatie Avenue, Emmarentia, Johannesburg 2092, South Africa

Disaster as two buildings under construction collapses in Kiambu County

A five-storey residential building under construction caved-in in Kinoo

Afive-storey residential building under construction and which partly collapsed in Kinoo after developing cracks on Friday has no proper foundation, an engineer has revealed.

According to the Institution of Engineers of Kenya (IEK) president Engineer Nathaniel Matalanga, the Kinoo building is crumbling because it stands on a weak foundation.

"The Kinoo area and the larger Kiambu County has red soil which requires a large and strong foundation built with quality materials to support a building," said Eng. Matalanga.

He linked the rampant collapse of buildings to greedy developers whom he said hire bogus contractors instead of qualified professional engineers to build their houses. people will be very rare.

“If developers stopped shortcuts and greed and hired professionals, they will not lose their investment and we will have quality buildings,” he said.

He accused the Nairobi Metropolitan Service (NMS) of failing in its supervisory role, adding that some of its officials are bribed by developers to allow substandard buildings to be constructed. “If National Construction Authority (NCA) says the structure was not approved, how come the developer was allowed to build it to the fifth floor?” he questioned.

Matalanga said NMS have ignored the law which requires the developers to seek the advice of a structural engineer before they started any construction, calling on the government to crack the whip on rogue developers and contractors.

Matalanga said if not stopped, the country will witness more cases of buildings under construction collapsing and killing people. NCA officials who visited the Kinoo structure said the entire structure will have to be brought down and that investigation will commence immediately to establish if the law was followed during the construction. Eng. Matalanga, further, accused NMS through the Department of City Planning of failing to supervise physical constructions in the city.

Residents said the owner of the building visited it on Thursday after being informed that his structure had started showing signs of collapsing. "The owner came here on Thursday night before leaving without uttering a word,” said Ken one of the resident that lives near the ill-fated building narrated. “People living near here left yesterday because it was just a matter of when before it came down,” he narrated.

On the same county, a similar tragedy befell Gachie residents where three people have been killed while dozens are injured after a building collapsed in Gachie, Kiambu County. According to area police boss Ali Nuno the site engineer has not been at the scene, and therefore it is hard to ascertain how many people were working before the building under construction collapsed. The Gachie building is said to have caved in when the workers were putting up a slab for the sixth floor.

“You cannot build a five-story structure on a narrow foundation without the service of a structural engineer, it will collapse,” he emphasized.

The IEK boss urged the government to create a conducive environment for professionals especially those in the engineering profession to reduce deaths and losses witnessed during such unfortunate collapses.