How to Design an Earthquake Proof Building in SketchUp
Simple earthquake proof building design. Is it even a thing? Yes, it can be a simple task to create a design for an earthquake-proof building, as long as you have the right tools… and in this case the perfect tool is SketchUp. If you’re researching earthquake-proof-building-design, read on. This article dives into what are the design features of an earthquake proof building and reveals which building design will best withstand an earthquake. By the end you’ll understand how earthquakes affect buildings, know ways to make a structure earthquake-proof, which materials to use, and more.
How earthquakes impact buildings?
Earthquakes can be extremely violent and catastrophically destructive. Even when they measure fairly low on the Richter Scale they can cause serious structural damage, simply by moving and shaking the solid ground beneath buildings, something called ‘generation of inertia forces’ and a big risk for building designers to factor in. The quake causes the ground to shake, moving the base of the building while the roof stays put. When the roof stays in its original position like this, it’s called inertia. Because the walls and columns are attached to it, the roof is dragged around along with the building’s base. As you can imagine the stresses and strains created can easily bring an unprepared structure down. Inertia forces cause shearing stresses, which leads to structures deforming. The ground shakes, the base of the building moves, the roof moves in a different way, and the difference makes internal forces in columns that bring the column back to its original position. There’s also the damage caused by horizontal and vertical shaking. While structures are designed to withstand vertical loads, earthquakes shake the ground in three directions. Vertical loads add or take away from existing loads. Horizontal shaking creates inertia along with lateral displacement, crucial to the structure’s strength. No wonder quakes create such powerful structural stresses that buildings collapse or are quickly damaged beyond repair.
How to make a building earthquake proof
First in our guide to simple earthquake proof building design, here’s a broad-brush look at how to make a place safe. Earthquake-proof buildings are carefully designed to withstand the destructive forces unleashed when the earth moves. So what are the design features of an earthquake proof building? Whatever the circumstance, they tend to focus on five key solutions. An appropriate, flexible foundation provides strength and durability exactly where it’s needed, at the point where the building and the earth meet. Seismic dampers reduce the impact of shaking. Thanks to them a design will be able to handle severe input energy and slash harmful deflections, forces and accelerations. Seismic dampers come in a variety of types: viscous dampers, friction dampers, yielding dampers, magnetic dampers, and tuned mass dampers. Shielding structures from vibrations keeps the elements of a building where they belong, more able to stay put simply because they vibrate less. Structural reinforcement adds core strength to the whole thing. And using adequately ductile materials means the structure can flex and bend safely rather than crack and break. Let’s take a detailed look at these in action.
Creating a Flexible Foundation
What are the design features of an earthquake proof building? Flexibility means a lot. One of the simplest ways to mitigate the impact of earth movements is to construct buildings on top of flexible pads. These cleverly isolate the foundation from the earth beneath, making them a key aspect of simple earthquake proof building design. This is called base isolation, done by constructing the building on top of flexible pads made of steel, rubber and lead. If an earthquake strikes it’s the isolators that vibrate, leaving the building stable. This alone makes a big difference, which is why it’s widely used in places where there’s a high risk of earthquakes. A good example is the 750 mile-long San Andreas Fault in California, which marks the tectonic boundary between the Pacific Plate and the North American Plate. It’s good to know the SketchUp 3D warehouse includes useful pre-made examples of anti-earthquake building foundations, ready for you to download and use as your basis and created to save you time. Take a look at this one, for example, which clearly reveals how the flexible foundation pads do their magic.
Counter Forces with Damping
Which building design will best withstand an earthquake? It’s also about something called damping. Earthquake resistant buildings include features designed to absorb the dramatic shocks from a quake and render them harmless. They’re called seismic dampers and they suck up the destructive energy so the building doesn’t have to. There’s a relatively new way to do this using the miracle material graphene, a single layer of carbon atoms with remarkable properties. Graphene is the strongest material in the world, with a strength of 42 N/m and an intrinsic strength of 130 gigapascals. It’s two hundred times stronger than the toughest steel and is also unusually elastic. No matter what the stresses and strains are, graphene stays the same. Adding a layer of graphene on top of a natural rubber pad works wonders to absorb the shockwaves. There are useful and inspiring 3D models of buildings including seismic dampers in the SketchUp 3D warehouse, ready for you to use and make your own. Have a look at how the dampers work in this seismic tower design, for example.
Shield Buildings from Vibrations
Scientists are busy exploring various ways to shield buildings from earthquake vibrations by diverting the energy elsewhere. One way they’ve achieved it is using 100 concentric plastic and concrete rings buried at least a metre below the building’s foundation. The idea is that the rings work to absorb the vibrations, which die down significantly before they reach the foundation and the building above it. The idea comes from the amazing ‘invisibility cloaks’ designed to hide objects by bending light waves around them, something used to hide fighter planes. Physicists from the UK and France found they could harness the same principles to hide an object from the destructive waves made by an earthquake. It’s possible to shield a building so an incoming earthquake wave acts like the building isn’t there, a lot like water flowing around a rock in a river. It works because the wave pattern generated by an earthquake, like water, can bend smoothly around the building, effectively making it invisible to the wave and redirecting vibrations around it. The rings we mentioned can even be tuned to different wavelengths to cope with the differing wavelengths created by a quake.
Structural Reinforcement
Quake-proof structural elements are also a big deal, involving shear walls, diaphragms, and moment-resisting frames. Shear walls are designed so they help a building keep its shape when a quake is moving it around, usually supported by diagonal cross braces made of steel. You can imagine how a structure that keeps its shape in the first place is less likely to collapse. A diaphragm is basically a horizontal structural element like a floor or roof, specially designed to transmit lateral loads to the building’s vertical resisting elements. Earthquake-resistant buildings have these elements on their own decks, strengthened horizontally so they share the violent force loads and make them less destructive. Moment-resisting frames are structures placed among a building’s joints. They let columns and beams flex and bend, rather than break because they’re stiff and resistant to moving. Again there are some cool examples to use, ready made, at the SketchUp 3D Warehouse, for example this shear wall design, and this floor and ceiling diaphragm. You’ll also find this pre-made design for an earthquake proof house interesting.
Ductile, Earthquake-Resistant Materials
Next, the materials. Obviously some materials are better at resisting damage from quakes than others so it is really important to choose the right building materials for your earthquake-resistant design. Ductility is the feature you’re looking for, since materials with high ductility absorb large amounts of energy without breaking. Structural steel is one of the most ductile materials of all, which is why it’s so critical to modern buildings in earthquake zones. Specially-engineered, fibre-reinforced concrete has similar properties. Interestingly, wood is also a good material for resisting earthquakes. As you can imagine there are plenty of useful pre-designed structural components in steel and wood available from the SketchUp 3D Warehouse. Take a look at this steel joist girder, and this wooden flooring frame. Now you know the basics around simple earthquake proof building design, designing a building or other structure to resist earthquake damage. What will you design first? You might want to check out the enormous collection of SketchUp tutorials, and even test-drive the Pro version of the software for yourself, free for 30 days.
*Please note that this blog post is to act purely as a guide, no safety professionals were consulted during the creation of this guide – always consult with an expert before going ahead with projects of this nature*