An earthquake and its effects on a building can lead to its collapse and the occurrence of a devastating disaster. During such events, some buildings easily fall, while others are not severely damaged. But the question is, what is the cause of a building’s collapse during an earthquake? Why do buildings not withstand earthquakes for long and easily collapse, causing irreparable damage? Is the problem related to their infrastructure, or does it stem from elsewhere? In this article by Hbboard, we have attempted to examine the most common cause of a building’s collapse during an earthquake.
Why do some buildings collapse during an earthquake?
The primary cause of structural collapse during earthquakes is often linked to their design, construction, and maintenance. However, other factors can contribute to building collapse during earthquakes, the most significant of which are:
Poor building design
Poor building design is a major contributing factor to the collapse of buildings during earthquakes. Especially in the case of structures that lack inherent earthquake resistance, the probability of collapse during seismic activity is significantly higher, and they are more prone to crumbling. Inadequate building design can even be linked to the utilization of subpar materials and non-standard construction techniques.
Faulty construction
Another cause of collapse is faulty construction, which occurs when buildings are not constructed according to the intended plans and designs. For example, if a building’s foundation is not properly excavated or if the building lacks proper reinforcement, it is more prone to collapse during an earthquake.
Neglect and improper maintenance
The third cause of the structural collapse is poor maintenance. Inadequate upkeep of buildings can weaken their integrity and increase their vulnerability. For instance, any cracks in the foundation can significantly raise the likelihood of a building collapse during an earthquake.
Soil liquefaction
Another cause of building collapse during earthquakes is soil liquefaction. In certain conditions, soil loosening and water saturation is possible. Under such circumstances, the soil can temporarily lose its strength and stiffness. However, the occurrence of an earthquake in these soils can lead to building collapse. This phenomenon is known as seismic soil failure and, unfortunately, it can happen even during low-magnitude earthquakes, resulting in significant human and financial losses.
Furthermore, constructing buildings on loose, easily liquefiable soils can intensify the seismic impact and greatly raise the probability of damage. Specifically, areas in close proximity to fault lines or situated near steep slopes are particularly vulnerable, increasing the risk of soil settlement and building collapse in these regions. Therefore, it is imperative to thoroughly investigate the soil conditions in an area and employ suitable foundation design techniques to mitigate the potential damage caused by earthquakes.
Lack of construction and seismic retrofitting standards
The lack of seismic-resistant building codes and inadequate implementation and enforcement of regulations in earthquake-prone areas are critical factors in ensuring structural safety. Failure to have stringent regulations or non-compliance with existing ones can significantly elevate the risk of building collapse during seismic events. Many older buildings were constructed before modern seismic design standards were established, making them more susceptible to damage. It is imperative to retrofit these structures, implement modernization measures, and adhere to current construction laws, to improve their seismic resilience and reduce the potential for collapse.
Weakness of columns
Another common cause of building collapse during an earthquake is the presence of short columns, which compromises the structural integrity of buildings. A short column refers to a type of column with a significantly lower height than others. Some factors that can contribute to the shortening of columns and their impact on building structures include:
– Construction of beams at mid-height of the columns.
– Construction of brick/block partition walls adjacent to the columns.
– Construction on sloping terrain, where the column height decreases on the upper side of the slope.
The effect of short columns occurs during an earthquake when the length of certain columns on a specific floor is reduced. This situation leads to increased shear forces between the short columns compared to the other columns, ultimately resulting in building collapse. These columns need to be identified and reinforced to strengthen buildings and prevent failure.
Poor ductility
Ductility is a crucial factor considered in the design of structures to enhance building strength. Insufficient ductility in a structure can lead to an increased risk of building collapse during an earthquake as it fails to effectively absorb the energy generated. Architects and contractors must have a thorough understanding of structural ductility. When reinforced concrete is used in building construction, it is essential to strictly adhere to instructions on its proper usage. Inappropriate plasticity between beam-column joints or column-foundation connections can result in structural damage and collapse during an earthquake.
One effective factor in ensuring proper structural plasticity is the use of seismic-resistant construction materials. Undoubtedly, the flexibility of materials used in building construction correlates with their earthquake resistance.
Inadequate resistance and improper design
One of the primary factors contributing to building collapse during an earthquake is the lack of structural resistance and appropriate design. Buildings must be designed to withstand lateral forces and ground movements caused by seismic activity. However, various factors can lead to a decrease in the building’s resistance to these forces, including:
- Inadequate construction practices
- Use of low-quality materials
- Poor structural design
- Insufficient reinforcement elements
- Improper connections and uneven load distribution within the building
One of the newer high-strength construction materials that are resistant to both earthquakes and fire is prefabricated panels, which have gained widespread use due to their numerous characteristics and advantages. In addition to various benefits in building renovation, they have many applications in the floor and interior wall insulation.
Plan irregularity and stiffness
Plan irregularity and stiffness are effective factors in strengthening buildings against earthquakes. They significantly impact the layout and appearance of a building. However, irregular stiffness in the building’s plan can be one of the main causes of building collapse during an earthquake.
Plan stiffness irregularity in buildings occurs when lateral stability elements of the building are positioned outside its center. These conditions can induce a torsional response in the building, known as torsion action. The greater the distance between the center of mass and the center of stiffness, the stronger the torsional response. This can potentially lead to the collapse of the building during an earthquake.
Conclusion
The collapse of buildings during an earthquake is a complex problem that can be caused by different factors. Inadequate structural resistance and design, the vulnerability of non-structural elements, soil conditions, and the absence of seismic reinforcement and construction regulations all contribute to building collapse during an earthquake. The best solutions to reduce these risks and prevent building collapse and resulting damages during an earthquake involve retrofitting the building and adhering to construction guidelines while utilizing modern earthquake-resistant building materials such as prefabricated panels.
