Narrative Report on “Seismic Isolation System: Principles, Applications, and Code Requirements”

Venue: Online (Zoom)

February 17 and 24, 2023

Session 1: February 17, 2023 (1:30 – 5:30 PM)

            The Session 1 seminar started with the Introduction to the webinar conducted by Dr. Rodolfo P. Mendoza, Jr., M.ASEP. He presented the overview of the entire topics for the Day 1 seminar. The 1^st topic of the webinar is the Implications of the National Structural Code of the Philippines (NSCP) 8^th Edition Seismic Code Provisions on Seismic Isolation Requirements and was presented by Engr. Adam C. Abinales, F.ASEP. He presented the overview of the Seismic Isolation Requirements to be incorporated on the latest NSCP (2023) 8^th Edition, in order to insure that a certain building performs the targeted seismic performance level in accordance with the Performance Based Design (PBD) seismic standards. He added the overview of the revised code particularly on Earthquake Loads, Equivalent Linear Method (Linear Static Analysis), and Linear Time History Analysis (Linear Dynamic Analysis).

The 2^nd Topic is the Applications of Seismic Isolation to Reinforced Concrete Buildings and was presented by Dr. Denim Feng, Chief Researcher, Fujita Corporation, Tokyo, Japan. He discussed about the Application of Seismic Isolators to a 7-storey Reinforced Concrete Building in Japan. He found-out that for a 7-storey RC building, only around 15-20% efficient is the Equivalent Linear Method (Linear Static) and around 80-85% efficient is the Time History Analysis (Non-linear Dynamic). He added that around 90% of the buildings in Japan have Rubber Bearing Isolators which means that most of the structures in Japan are really seismic resilient regardless of how strong its magnitude is.

The 3^rd and final Topic of the Session 1 webinar is the Application of Seismic Isolation Technology in the Philippines and was presented by Engr. Ruel B. Ramirez, MSCE, M.ASEP. He discussed about the importance of the installation of Seismic Isolation devices on each structure particularly on Reinforced Concrete. He re-iterated the seismic performance of a conventional structure versus a seismic isolated structure in terms damage, risk, downtime, initial cost and repair/maintenance cost. He added that Linear Dynamic Seismic Analysis is good for initial analysis and Non-linear Time History Seismic Analysis as the final analysis especially in the incorporation of seismic isolators that takes into account the bending of structures.

Session 2: February 24, 2023 (12:30 – 5:30 PM)

            The Session 2 seminar started with the Principles and Fundamentals of Seismic Isolation by Prof. Taiki Saito a Professor in Toyohashi University of Technology. He briefly discussed about the seismic performance comparison between a conventional structure and a seismic base isolated structure. A seismic isolated structure performs under immediate occupancy and even in operational level which makes it a seismic resilient structure. He also discussed briefly on the design of a base isolation layer, period, damper and bearing. He concluded that majority of the buildings in japan is Earthquake Resilient, Promotion of Retrofitting is Necessary especially for Old Buildings, Proper Dissemination for Seismic Isolation is necessary, Proposal for ISO standard on Seismic Isolation, and Vibration Control devices is especially adopted for high-rise buildings.

            The 2^nd Topic of Session 2 is the Applications of Seismic Isolation to Steel Buildings by Dr. Agostino Marioni, Chairman of Hirun International. He briefly discussed about the recent earthquake in turkey that a good seismic standard is essential to assure the safety of the constructions and especially to save human lives in case of an earthquake; authorities, designers and contractors are responsible for the correct application of the standards; and, base isolation can really protect structures and people from an earthquake. Also, he briefly described the 3 different types of sliding pendulum isolators namely: Single sliding surface, Double sliding surface, and Double sliding surface with centre articulation. He tackled about the importance of sliding materials that it is considered as the most important component of the sliding pendulum isolators. Sliding materials provide three important performances: High compressive strength, Long service life, and Resistant to high temperatures. He concluded that Seismic isolation is the most effective system to protect a structure from an earthquake, Sliding pendulum isolators are the most efficient and the most cost effective, Base isolation greatly simplifies the design, Quality assurance of the devices is of primary importance, and the best solution shall always be evaluated case by case. 

The 3^rd and Final Topic of Session 2 is the Specifications and Test Requirements for Seismic Isolation Systems by Engr. Javier L. Gimenez, a Seismic Engineer from Kawakin Core-Tech Co. He discussed about the critical role of seismic isolators wherein it has the necessary characteristics of Vertical load bearing capacity, Capacity to accommodate rotations, Flexibility in horizontal direction, Energy dissipation capacity and Re-centering capability after an earthquake. He added about the design of an isolation system to cover the Vertical capacity (Service and EQ conditions), Deformability (EQ conditions), Energy dissipation capacity (EQ Loads reduction), and Horizontal Stiffness (Structural Flexibility and Resistance against Torsion). He also tackled briefly about the isolator placement and the process of installation. He then concluded that: Seismic isolators can eliminate or minimize the risk of seismic damage in buildings and bridges under a strong earthquake, Structural response of a seismically isolated structure mainly depends on the performance of the isolators, and Special attention for Quality control and Specifications of the isolators.

            The last part of the 2 day webinar is the avenue for the Open Forum wherein the Key Officials from ASEP get to have an open discussion with the Key Note Speakers Abroad. Their key discussions are as follows: 

·         Incorporation of Seismic Isolation Specifications in our latest National Structural Code of the Philippines to be implemented as soon as possible for the design of new buildings and retrofitting of old buildings in the country. Also, adaptation of the Seismic Isolation Specs to the National Building Code of the Philippines.

·         Comparison between the Conventional Designed Structure vs Seismic Isolated Designed Structure (They found out that around 25% Cost Savings for Seismic Isolated Structure vs Conventional structure).

·         NSCP Migration to Japan code for simplification compared to US code.

·         To have an ASEP Committee on Seismic Isolation Design and Installation.

·         To conduct formal training workshop on Seismic Isolation Analysis, Design and Installation for future structural engineers and designers.