When we think of earthquakes, the first thing that comes to mind is China, Japan, or California. But did you know that even with lower seismicity, Switzerland is also a seismically active country?
The seismic design (and its importance) has only recently been recognized in Switzerland – in the early 90s. This means that the older buildings before the nineties were built without considering a potential seismic impact – which can cause severe damages.
It’s important to consider the seismic risk when designing reinforced concrete structures in Switzerland, but this issue can be complicated. The complexity is due to the higher uncertainty in the estimation of the correct design loads and the capacities of structural elements.
With more people living in earthquake-prone areas, it’s essential that we take the necessary steps to satisfy the safety criteria and ensure an excellent seismic design of reinforced concrete structures – especially since they’re so challenging to retrofit!
This article will cover the need for a good seismic design of reinforced concrete structures in Switzerland today!
But first, let’s take a look at the seismic vulnerability of Swiss buildings before 1990.
The significance of seismic risk in Switzerland was recognized in the early nineties, only after the seismic code regulations were established in 1989. Prior to these regulations, most of the old structures were designed without taking into consideration a possible quake effect – making them highly vulnerable to earthquakes.
Most of these structures constructed between 1945 and 1989 still exist today and have a significant contribution to the overall seismic risk.
These structures bear an extremely high cost of retrofitting, but the cost can be even higher if they crash during some seismic events.
In one survey conducted for over 50 older buildings in medium seismic areas, it was established that there is a potential seismic vulnerability in the buildings due to their masonry walls that were considered as “weak links.”
So, the need for effective seismic design of reinforced concrete structures was an absolute necessity.
Even though the seismicity in Switzerland is only low to medium, the structures can be subject to deformations in case of stronger ground motions. That’s why a good seismic design is essential from the very beginning.
A good seismic design concept will ensure that the structure can behave well even during strong ground motions and serious earthquakes.
However, if engineers fail to implement a proper seismic design and don’t consider the deformations or forces in some specific elements in the structure due to torsion, it can lead to structural distress, or eventually, collapse.
Having an effective seismic design of reinforced concrete structures is also beneficial from the aspect of structural safety and minimizing the repair work after an earthquake event.
In addition, the engineers need to make a significant effort to tie all parts of a structure that need to stick together in a secure manner.
Many studies have shown that properly designed and detailed reinforced-concrete buildings come with all the necessary stiffness and strength required to withhold severe earthquake loading.
After the Swiss seismic code regulations in 1989, considerable advances in the past three decades in the seismic design area were made.
Today, the new modern seismic design concepts minimize the earthquake risks of almost all buildings in Switzerland. This concept is also recognized as “performance-based design” and eliminates most of the post-earthquake casualties.
And for maximum seismic performance of the buildings, engineers in Switzerland today have successfully integrated the three important parameters in their seismic designs:
– Lateral deformation capacity (ductility, stiffness, and cyclic energy dissipation)
– Lateral structural resistance
– Response of non-structural elements
However, as with all developing areas, the seismic design of reinforced concrete structures can be further improved and refined. These refinements can be done as more info on earthquakes is accumulated and more analyses are made to structural configurations.
Building structures in earthquake-prone areas is a responsibility that needs to be taken seriously. The Swiss government has set very high seismic safety criteria for reinforced concrete structures. However, it can still take years before these are fully met by every engineering company out there.
For this reason, Breon and the partner offices are there for you if you need seismic design of reinforced concrete structures in Switzerland or elsewhere! Together with our partners of specialized engineers, we help you meet the safety criteria and comply with today’s earthquake-resistant building codes.
Contact Breon and its partner offices today to learn how we can help you design or retrofit your building to be earthquake-resistant.