We have seen in the news over the last few years, more and more shocking stories around the damage and devastation an earthquake can cause. The majority of this damage coming from buildings and other structures falling down, either during the quake or in the sometimes more catastrophic aftershocks. As structural engineers it is our job to continuously develop ways to make buildings stronger and safer in order to reduce the devastation from an earthquake or other earth moving events.
In order to design and consequentially build structures that can withstand earthquakes, engineers must first understand the stresses caused by shaking. In order to do this engineers and scientists install instruments in buildings (near to the ground) that are in earthquake prone areas to measure how the structures respond during a quake. This means that after an earthquake, data is collected from these readers that help to inform engineers on how the buildings respond to the stress. From here we are able to develop new ways to build ‘Earthquake Proof’ structures.
Scientists began measuring earthquakes in 1880, but it wasn’t until the 1940’s that instruments were installed on buildings in order to measure their response to earthquakes. This method was rolled out in more and more countries during the 50’s, 60’s and 70’s meaning that buy the early 80’s scientists and engineers had plenty of data to develop new ways to make buildings stronger under stress. Today these readers are installed on all sorts of buildings across the globe, meaning scientists and engineers are constantly receiving data to improve the way we build.
Building earthquake resistant structures
No building can be completely earthquake proof, however, safer building methods have come on leaps and bounds over the past three decades. According to most building codes, earthquake resistant structures are meant to withstand the largest quake that is likely to happen in that location. Meaning that the damage should be minimised for rare earthquakes and the loss of functionality should be limited for smaller, more frequent ones.
Currently there are many philosophies in earthquake engineering, many making use of the data acquired from past earthquakes, computer simulations and information gained from the instruments installed from the 1940’s. These range from sizing the structure to be strong and ductile enough to survive the shaking of an earthquake with acceptable damage, to using base isolation (a collection of structural elements which should substantially decouple a superstructure from its substructure resting on a shaking ground thus protecting a building or non-building structure‘s integrity) or using structural vibration control technology to minimize any forces.
In addition to this, engineers are now using different building materials such as precast concrete, which has proven to be a pretty good material to help keep structures strong whilst under stress. Another retrofitted seismic protection is the Combined Vibration Control Solution. Developed by architect Merrill W. Baird, this design requires the structure to be put on high damping rubber bearings. However, it is worth noting that this method is only possible if the structures foundations are elevated.
Steel plate wall systems are another popular way to protect a building from earthquakes and one of the very few methods that was specifically designed to withstand seismic activity. This system consists of steel infill plates bound by a column-beam system. These infill plates are placed on each level of the building within a framed bay of structure.
There are many ways in which structural engineers can help to reinforce buildings to withstand earthquakes and the technology is continuously being refined and updated.
We might not have many earthquakes in the UK, but Keeping structures strong and safe is our business. If you’re looking to convert, renovate or build anything talk to the experts here at Green Structural Engineering.