Earthquakes don’t kill people, buildings do. Most collapses that occur during earthquakes are not actually caused by the earthquake itself. A building’s seismic risk is primarily determined by its strength and stiffness. The stiffer the building, the less it will move or deflect when seismic waves move through the structure.
Before an earthquake happens, a structure is stationary, resting only on vertical gravity loads associated with the weight of the building, its occupants and contents. When a tremor occurs, the ground moves, causing the foundation to move along with it. The roof and upper stories of the structure try to remain stationary because of inertia. By the time the roof starts to move in the direction of the foundation, the foundation is then moving back to its original place. This oscillating movement continues until the earthquake stops. It’s the back and forth movement of the building that determines its fate.
Every building already has what’s called a natural frequency, which is basically a structure’s natural vibration without the interference of any external forces. If an earthquake releases waves that are in tune to a building’s natural frequency, this can amplify the structure’s oscillating movement, causing it to become unstable enough to collapse.
Most states and local jurisdictions adopt building codes maintained by the International Code Council(ICC). The ICC’s seismic provisions represent the best guidance on how structures should be designed and constructed to limit seismic risk. SteelMaster’s earthquake-resistant structures strictly follow these codes to ensure safety once each building is erected.
Our earthquake proof building design features make Quonset HutsTM some of the strongest, most durable structures on earth. When seismic waves violently flow through a structure, the strength of the buildings oscillation depends on the building’s mass and its stiffness.
The stiffness of a building is extremely important when determining how it will hold up during an earthquake. Stiffness is measured in terms of drift or horizontal deflection. In order for a structure to remain stable, the load applied at any point must have a path allowing load transfer through each building part down to the foundation.
SteelMaster’s buildings are all made from high quality, commercial grade steel that is bolted together in an overlapping fashion. These steel arches are then secured to a sturdy concrete foundation, adding even more strength to this structure. During an earthquake, the load is transferred to the foundation through the ceiling and walls. A Quonset HutTM is constructed as one unit, which evenly distributes the energy caused by seismic waves to its concrete foundation with little chance of damage.
The Quonset Hut’sTM height and mass also add to its ability to stand during an earthquake. A heavier building’s mass will slow down the intensity of the oscillation, lessening the possibility of a collapse. Also, shorter buildings suffer significantly less damage than a taller one. Quonset hutsTM are normally much shorter than typical straight wall buildings.
The Quonset HutTM also has another unique feature that makes it safer than a traditional building. The 100% clear span design does not require the use of beams and trusses to support the structure. This eliminates the potential for weak spots inside of the building and few areas where the structure can become damaged, which can contribute to a collapse.
Engineers work closely with geologists and seismologists to predict earthquake motions which will allow them to prevent resonance induced collapses. They look at factors including soil type, fault type, and data from previous earthquakes.
The International Residential Code(IRC) designates the level of potential risk for dwellings by assigning a structure to a seismic design category based on location. This scale ranges from the lowest level of risk, A, to the most severe, level E.
SteelMaster’s Quonset HutsTM follow seismic building codes that help to keep people safe. Over the last few decades, poorly built structures have caused thousands of deaths all over the world. Although these deadly events cannot be predicted in advance, SteelMaster is working to make sure our customers are prepared when disaster strikes.