10 Advanced Technologies for Earthquake-Resistant Buildings

During the Bronze Age, numerous thriving civilizations emerged, some of which constructed remarkable cities featuring organized grids and advanced plumbing systems. However, scientists now believe that tectonic movements might have played a role in the downfall of these ancient societies. For instance, studies at Megiddo (located in modern-day Israel) indicate that a significant earthquake could have caused widespread destruction, leaving behind layered ruins. Similarly, a sequence of quakes may have led to the abrupt collapse of the Harappan civilization (in present-day Pakistan) around 1900 B.C.E.

Even today, we remain vulnerable to the devastating impacts of strong earthquakes. Modern structures and bridges, when subjected to the abrupt sideways forces generated by seismic activity, can suffer catastrophic failures, endangering lives. This issue has intensified with urbanization and the increasing size of buildings. Fortunately, architects and engineers have developed innovative technologies over recent decades to ensure that homes, apartment complexes, and skyscrapers can withstand seismic forces, allowing occupants to evacuate safely and begin recovery efforts.

In the following sections, we explore 10 cutting-edge earthquake-resistant technologies. While some have been in use for years, others, like the first entry in our list, represent newer concepts still undergoing testing.

10: The Levitating Foundation

For decades, base isolation has been a preferred method among engineers and seismologists to safeguard structures during seismic events. This technique involves decoupling a building’s base from its upper structure. A common implementation uses lead-rubber bearings, which feature a lead core surrounded by layers of rubber and steel. These bearings are secured with steel plates to both the building and its foundation, enabling the foundation to shift independently during an earthquake, thereby protecting the structure above.

Japanese engineers have revolutionized base isolation by introducing a system that elevates buildings on an air cushion. Here’s the process: Sensors on the structure detect seismic activity, triggering an air compressor. Within half a second, the compressor releases air between the building and its foundation, lifting the structure up to 1.18 inches (3 centimeters). This air cushion isolates the building from destructive forces. Once the earthquake ends, the compressor deactivates, and the building gently returns to its foundation. All that’s missing is the iconic theme from "Greatest American Hero."

9: Shock Absorbers

A proven technology aiding buildings to withstand earthquakes is inspired by the automotive sector. The shock absorber, a device that mitigates unwanted spring motion in vehicles, is well-known. These devices reduce the intensity of vibrations by converting the kinetic energy from the suspension's movement into heat, which is then dispersed via hydraulic fluid. In the realm of physics, this process is termed damping, hence the alternative name for shock absorbers as dampers.

Dampers prove invaluable in constructing buildings resistant to earthquakes. Typically, engineers install dampers on every floor of a structure, connecting one end to a column and the other to a beam. Each damper includes a piston head that operates within a silicone oil-filled cylinder. During an earthquake, the building's lateral movement forces the piston to compress the oil, converting the seismic energy into thermal energy.

8: Pendulum Power

Damping manifests in various ways. For skyscrapers, one effective approach is to hang a massive weight near the building's apex. This weight is held by steel cables, with viscous fluid dampers positioned between the mass and the structure it safeguards. During seismic events, the pendulum swings in the opposite direction, effectively neutralizing the energy.

These systems are known as tuned mass dampers, as each pendulum is meticulously calibrated to match a building's natural vibrational frequency. When seismic activity induces resonance, the structure can vibrate excessively, risking damage. The tuned mass damper's role is to offset this resonance, reducing the building's dynamic response.

Taipei 101, named for its 101 floors in the 1,667-foot (508-meter) tower, employs a tuned mass damper to mitigate vibrations from earthquakes and high winds. Central to this system is a massive 730-ton (660-metric-ton) golden sphere, supported by eight steel cables, making it the largest and heaviest tuned mass damper globally.

7: Replaceable Fuses

In electrical systems, a fuse acts as a safeguard by breaking the circuit when the current surpasses a specific threshold. This interruption prevents overheating and potential fires. Once the issue is resolved, replacing the fuse restores normal operation.

Scientists from Stanford University and the University of Illinois are exploring a comparable approach to create earthquake-resistant structures. Their innovation, termed a controlled rocking system, involves flexible steel frames that can rock atop the foundation. However, this alone isn't sufficient for optimal performance.

Alongside the steel frames, the team incorporated vertical cables that tether the top of each frame to the foundation, restricting excessive rocking. These cables also possess a self-centering feature, enabling them to realign the structure post-earthquake. Additionally, replaceable steel fuses are installed between frames or at column bases. These fuses absorb seismic energy during rocking, and if damaged, they can be easily and affordably replaced to return the building to its pre-earthquake state.

6: Rocking Core-wall

In contemporary high-rise construction, engineers employ core-wall designs to enhance seismic resilience cost-effectively. This approach features a reinforced concrete core at the building's center, typically enclosing elevator shafts. For skyscrapers, the core wall can be massive, often exceeding 30 feet in width and 18 to 30 inches in thickness.

Although core-wall construction improves earthquake resistance, it has limitations. Studies show that fixed-base buildings with core-walls may still suffer from inelastic deformations, high shear forces, and harmful floor accelerations. Base isolation, which involves placing the structure on lead-rubber bearings, mitigates these issues by reducing floor accelerations and shear forces. However, it doesn't eliminate deformation at the core-wall's base.

A more effective approach for earthquake-prone areas combines a rocking core-wall with base isolation. The rocking core-wall allows movement at ground level, preventing permanent deformation of the concrete. Engineers reinforce the lower floors with steel and use post-tensioning throughout the structure. Post-tensioning involves threading steel tendons through the core wall, which, like rubber bands, can be tensioned with hydraulic jacks to enhance the wall's tensile strength.

5: Seismic Invisibility Cloak

Waves are often associated with water or sound, but earthquakes also generate waves, categorized by geologists as body and surface waves. Body waves travel swiftly through Earth's interior, while surface waves move more slowly through the upper crust. Among surface waves, Rayleigh waves cause vertical ground motion, leading to the shaking and destruction typical of earthquakes.

What if seismic waves could be intercepted or redirected away from urban areas? Scientists propose a "seismic invisibility cloak" to achieve this. Engineers suggest constructing this "cloak" from 100 concentric plastic rings buried under a building's foundation [source: Barras]. As seismic waves approach, they enter the rings and are confined within the system, preventing energy transfer to the structure. The waves bypass the building and exit the rings on the opposite side, continuing their journey. This concept was tested by a French team in 2013.

4: Shape Memory Alloys

As previously mentioned, material plasticity poses a significant challenge for earthquake-resistant construction. Plasticity refers to the deformation that occurs when forces are applied to a material. If the forces are excessive, the material's shape may be permanently altered, impairing its functionality. Both steel and concrete, commonly used in construction projects, are susceptible to plastic deformation.

The shape memory alloy is a revolutionary material capable of withstanding heavy strains and reverting to its original form. Engineers are increasingly exploring these smart materials as alternatives to conventional steel-and-concrete structures. Nitinol, a nickel-titanium alloy, stands out for its 10 to 30 percent greater elasticity compared to steel [source: Raffiee]. A 2012 study by the University of Nevada, Reno, demonstrated that bridge columns made with nitinol and concrete outperformed traditional steel-and-concrete columns in seismic tests, sustaining significantly less damage [source: Raffiee].

3: Carbon-fiber Wrap

While earthquake resistance is crucial in new constructions, retrofitting older buildings is equally vital. Engineers have discovered that integrating base-isolation systems is both practical and cost-effective. Another innovative solution involves fiber-reinforced plastic wrap, or FRP. This material is created by combining carbon fibers with polymers like epoxy, polyester, vinyl ester, or nylon, resulting in a lightweight yet exceptionally strong composite.

For retrofitting, engineers wrap this material around concrete columns in buildings or bridges and inject pressurized epoxy into the space between the column and the wrap. This process may be repeated multiple times, creating a reinforced beam with enhanced strength and flexibility. Remarkably, even earthquake-damaged columns can be restored using carbon-fiber wraps. Studies show that wrapped bridge columns exhibit a 24 to 38 percent increase in strength compared to unwrapped ones [source: Saadatmanesh].

2: Biomaterials

While current earthquake-resistant materials like shape memory alloys and carbon-fiber wraps are effective, engineers look to nature for future innovations. The humble mussel, a mollusk that clings to ocean rocks, offers inspiration. Mussels produce sticky fibers called byssal threads, which combine stiff and elastic strands to absorb shock and dissipate energy. Researchers have identified an optimal 80:20 ratio of stiff-to-flexible fibers that enables mussels to withstand crashing waves [source: Qin]. This natural design could inspire the next generation of construction materials.

Spider silk, known for its strength surpassing steel, also exhibits unique dynamic properties under strain. MIT scientists discovered that spider silk transitions from stiff to stretchy and back to stiff when pulled, a nonlinear response that makes it incredibly resilient. This behavior makes spider silk a promising model for developing advanced earthquake-resistant materials.

1: Cardboard Tubes

In developing nations, where earthquake-resistant technologies are often too costly, are communities destined for high casualties during seismic events? Not necessarily. Engineers worldwide are innovating with locally available materials to create resilient structures. In Peru, plastic mesh reinforces traditional adobe walls. In India, bamboo strengthens concrete, and in Indonesia, homes are built on sand- or stone-filled tire bearings.

Even cardboard can be transformed into a robust building material. Japanese architect Shigeru Ban has pioneered structures using polyurethane-coated cardboard tubes as primary supports. In 2013, Ban's Transitional Cathedral in Christchurch, New Zealand, featured 98 large cardboard tubes reinforced with wooden beams [source: Slezak]. This lightweight, flexible design outperforms concrete during earthquakes and poses less risk to occupants if it collapses. It’s a reminder to appreciate the humble cardboard tubes in everyday items like toilet paper rolls.