Optimized Design of LPB Isolators for a School Building Using Performance Targets

Chapter 9

Abstract
Earthquakes pose significant risks to educational buildings,
especially in seismic regions where ground shaking can cause severe
structural and non‑structural damage. School buildings must
maintain a higher level of safety because they accommodate a large
number of students and staff during working hours. Traditional
seismic design methods focus on increasing the strength and stiffness
of the structural system to resist earthquake forces. However, this
approach often results in large structural forces, potential damage to
structural members, and failure of non‑structural components such
as ceilings, partitions, and laboratory equipment.
Base isolation has emerged as an effective seismic protection strategy
for reducing the forces transmitted from the ground to the structure.
Lead Plug Bearings (LPB) are widely used base isolation devices that
provide flexibility through rubber layers and energy dissipation
through a central lead core. When an earthquake occurs, LPB
isolators allow controlled movement at the base of the structure,
thereby reducing the acceleration and deformation demands on the
superstructure.
This project investigates the optimized design of LPB isolators for a
reinforced concrete school building using performance‑based targets.
The study defines structural performance objectives such as limiting
inter‑storey drift, reducing floor accelerations to ensure student
safety, and minimizing base shear. A parametric study is conducted
by varying isolator stiffness, yield strength, and damping
characteristics to identify the most effective configuration. Structural
analysis results demonstrate that optimized LPB isolators
significantly improve seismic performance while maintaining
constructability and cost efficiency.
Keywords:LPB isolators, earthquake, Lead Plug Bearings, isolator
stiffness, yield strength.