Seismic Isolators: An anti-seismic technology to earthquake-proof buildings

Published October 1, 2021, 11:07 AM

by Enzo Luna

Engr. Ruel Ramirez with Seismic Isolator

An engineer in the Philippines recently introduced a groundbreaking solution to protecting the country’s buildings against earthquakes – the Seismic Isolator. Given that the Philippines belongs to the Pacific Ring of Fire and we are frequently experiencing earthquakes, the anti-seismic device could help and prevent much more damages if another ground shaking event happens.

Seismic Isolators were the dissertation of Engr. Ruel Ramirez, the Principal of Ruel B. Ramirez & Associates (RBRA). When he took his PhD at the Asian Institute of Technology (AIT), he wanted to find a viable solution to protect buildings from the damaging ground movement of earthquakes, which led him to discover that countries such as Japan, New Zealand, China, and the US were already using base isolators for their buildings. He then set out to study and bring the technology to the Philippines.

His engineering firm, RBRA, is the first to offer these devices in the country. They provide the design, supply, and installation of seismic isolators. These anti-seismic devices can be applied to new and existing structures, making them an effective and proactive solution for earthquakes.

Seismic Isolator ensures zero damage

The Seismic Isolator is an anti-seismic device that ensures zero damage to a building in the event of an earthquake. Its purpose is to isolate the building from the damaging ground movement by allowing it to slide with the ground. Since damaging earthquake movements are horizontal rather than vertical, a building with seismic isolators will simply sway instead of vibrating back and forth in varying directions due to inertial forces, which will cause deformation and damage.

Seismic Isolators can be of any shape depending on the building requirements but usually, they are cylindrical or square in shape, oftentimes composed of natural or high damping rubber with a lead core. The lead core stops and absorbs vibrations, while the rubber acts like a spring. Because it absorbs the seismic energy, floor acceleration will be reduced, thus preventing damage to the structure, and ultimately preventing the damage of the building and its contents.

RBRA Team at San Lazaro

“The concept of a rigid foundation is wrong,” says Ramirez. “What we should be doing is providing a flexible foundation. If you use conventional methods, the top of the building will be swaying against the ground, so it will tend to bend the structural elements which will eventually damage the non-structural components including utilities and will disturb all the occupants. If there’s a base isolator, this can be prevented.”

Seismic Isolators can be applied to new and existing buildings by cutting into the structural columns where they can be installed as the base. RBRA customizes the design of the isolator depending on the project—they customize its overall size, the bracket of the rubber, the size of its lead core, and other components needed to ensure the building will not move during an earthquake.

The applications for Seismic Isolators are endless. RBRA is in the process of designing and supplying base isolators for the buildings of De La Salle University, the new 5-storey building within the old compound of San Lazaro Hospital, the St. Vincent De Paul Church in Malate, and other government buildings. They are also working with the Bangko Sentral ng Pilipinas to have isolators installed in their Cebu and Davao regional offices.

Seismic Isolator Installation

Other Anti-Seismic Devices Offered by RBRA

Apart from the Seismic Isolator, RBRA also provides Viscoelastic Dampers. They significantly minimize the seismic impact on a building’s structural components, reducing the vibrations that would lead to damage. Installation consists of fortifying the existing columns with the dampers, which will then absorb the earthquake shock and prevent the structure from shaking. RBRA has retrofitted the 100-year-old China Banking Corporate Building with Viscoelastic Dampers, enabling it to stand strong for another 100 years.

“We should always remember that the shutdown of economic activity and deaths during an earthquake is attributed to the damage of buildings. If buildings will not collapse, everything will be fine. So, it is the building that we must protect from damaging earthquakes,” says Ramirez.