StrucSure

What it does

StrucSure is a variable damper designed for low-rise buildings, which are sensitive to high-frequency vibrations found in earthquake epicenters. It uses an algorithm to electromechanically modulate the control valve, adjusting the damping force in real-time.

Your inspiration

The Big One is an anticipated 7.2-magnitude earthquake that will affect densely populated cities along Metro Manila and nearby provinces, where low-rise structures are at greater risk due to their susceptibility to high-frequency waves found near the epicenter of the earthquake. This means that houses in particular are vulnerable and the potential damages to life and infrastructure are catastrophic. Despite the impending crisis, there is no available solution for the general public. This exposes the lacking preparations for earthquake damage mitigation and the need for a corresponding solution that will be available for the masses.

How it works

StrucSure is a VOD designed to protect low-rise buildings during earthquakes. It works by controlling the amount of silicone oil flowing inside a sealed cylinder. Attached to it is a bypass pipe with a valve that changes the size of a small opening, called an orifice. Sensors quantify the real time velocity and distance of the building’s movement, while a control system transmits data to a small motor that modifies the orifice size. When the building experiences rapid movement and requires greater resistance, the valve constricts, thereby elevating the pressure and decelerating the motion further. When the movement is less vigorous, the valve opens more extensively, facilitating flow and preserving energy. This system uses very little power and responds quickly, making it ideal for smaller buildings that need fast and reliable protection. It can be installed in new structures or added to existing ones without major changes.

Design process

The algorithmic framework of StrucSure focuses on the Proportional-Integral-Derivative (PID) controller, whose optimal tuning parameters will be determined iteratively using either the Ziegler-Nichols method or the Cohen-Coon method. Following the validation through SimuLink, this control algorithm will be translated into an Arduino code for it to be employed in the physical StrucSure damper. The performance of two control valves will be considered, which are the solenoid and the servo valve, with the selection predicated upon its capacity to rapidly achieve the desired damping force. The scaled low-rise building and StrucSure will be mounted on a shaking table, where these objects will be subjected to ground shaking similar to the Big One with an anticipated magnitude of 7.2. The earthquake data to be used are the April 2015 Gorkha earthquake with a 7.7 magnitude and the October 2023 Bohol earthquake with a 7.2 magnitude.

How it is different

Unlike conventional dampers that have a fixed damping capacity, StrucSure uses a variable orifice damper (VOD) that can adjust the damping force in real time depending on the intensity of the earthquake. What sets it apart is the use of a solenoid or servo valve controlled by an algorithm equipped with a PID controller, which allows it to shift between different damping levels quickly and efficiently using only a small amount of power. This makes it more responsive than passive dampers and more energy-efficient than active dampers. We also focused on making the design suitable for low-rise buildings, which are more at risk from high-frequency ground shaking. Since the materials for StrucSure are relatively cheaper than other semi-active dampers such as magnetorheological dampers, this device offers a revolutionary and cost-effective upgrade to current damping solutions.

Future plans

Our next step is to improve the prototype by refining the control algorithm and testing the damper under more realistic seismic conditions. We aim to scale the design for actual low-rise structures and explore retrofitting options for vulnerable buildings in Metro Manila. In the long run, we hope to develop this into a cost-effective, low-maintenance product that can be mass-produced and used in both new and existing buildings, especially in earthquake-prone and resource-limited communities.

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