Performance-Based Design Of Buildings For Earthquake Conditions Using Next-Generation Elastomeric Dampers

Project Summary

Structural vibrations caused by an earthquake can lead to damage of structures. As a result, structures will have to be repaired or possibility demolished. Passive dampers offer a means of reducing the structural hazards caused by earthquakes to structural systems. To develop the full potential of passive dampers, economical damper designs and performance based design procedures for structural systems need to be developed and validated.

The study will involve developing with Corry Rubber Corporation the next generation of elastomeric dampers. Large-scale elastomeric dampers will be constructed and real-time hybrid simulation methods used to perform a series of experiments involving simulated seismic loading on a building structure. An existing test bed, consisting of a large-scale damper that is coupled to an analytical model of the remaining part of the structure, will be expanded to include two large-scale dampers. The data collected from the experiments will be utilized to assess damper performance, calibrate and refine a newly developed analytical model for elastomeric dampers, and to assist in the establishment and validation of the performance-based design methodology.

Project Description

The project builds upon results from prior studies on elastomeric dampers, where a first-generation damper was constructed and mechanical properties for the damper were obtained. These studies helped to establish real-time hybrid simulation methods for structural systems with passive dampers, which led to preliminary assessment of these dampers for vibration control under seismic loading.

Based on the results from these prior studies, a first generation elastomeric damper developed by Corry Rubber Corporation was evaluted for use in reducing structural damage to buldings during the design earthquake. Tests were performed on the damper to establish their mechanical properties. Preliminary designs of a prototype structure using the passive dampers revealed that a large number of dampers were required in order to meet performance-based design objectives under the design earthquake. Tests on structures under earthquake loading conditions performed using real-time hybrid simulation methods confirmed the need for improvement in the damper design. In addition, the tests performed to establish the mechanical properties of the damper and in the hybrid simulations revealed that the damper exhibits slip and dissipate energy due to friction at moderate amplitudes of deformation. It was concluded that new analytical models have to be developed in order to accurately protray the hysteretic behavior of the damper, which is both rate-dependent due to its elastomeric composition and deformation amplitude due to slip.

The study will involve developing with Corry Rubber Corporation the next generation of elastomeric dampers. These dampers will result in a more efficient design, where fewer dampers are required to achieve design objectives for a structure. The tasks for the proposed project include: (1) providing input to Corry Rubber Corporation for constructing the next-generation of large-scale elastomeric dampers; (2) performing tests on the damper to establish the mechanical properties for a range of frequencies and deformation amplitudes; (3) revise the performance-based design procedure developed in prior research to incorporate any necessary changes based on the properties and characteristics of the new damper; (4) designing a low-rise prototype building with the dampers that enables selected performance objectives to be economically achieved in the structure during the design earthquake; (5) performing real-time hybrid simulation of the prototype building under a range of seismic hazards to validate the performance of the damper and the performance-based design procedure; (6) use the results from the mechanical property tests and hybrid simulations to calibrate and refine a newly developed analytical model for elastomeric dampers that can be utilized in time history analysis; (7) performing nonlinear time history analyses of the prototype building with dampers to investigate effects of parameters varied in the design (e.g, performance level, design criteria) and to further validate the performance-based design procedure.

The Real-time Multi-directional (RTMD) Earthquake Simulation Testing Facility has been in existence at the ATLSS Center for about four years. This facility has state-of-the-art servo-hydraulic equipment (servo-valves, accumulation and piping systems). Advanced testing methods have been implemented, enabling the real-time testing of structural components and systems. In the proposed project the dampers can be tested in real-time under realistic loading conditions using the real-time hybrid simulation method. This method enables the interaction of the dampers with the structural system to be included in the test, by creating analytical substructures of the remaining parts of the structural system that are coupled to the dampers.

Fabrication of compressed elastomer damper: (a) elastomeric material wrapped around longitudinal bar; (b) elastomeric material and bar compressed into the steel tube; (c) damper bottom view with additional bolted transverse bars in place and (d) installation to beam web

Compressed elastomer dampers in test setup

Comparison of experimental hysteresis and hysteretic model

Participants

Faculty

• James M. Ricles – Lehigh University
• Richard Sause – Lehigh University

Post-Doctoral Research Associate

• Theodore L. Karavasilis – Lehigh University

Academic collaborators

• Robert Michael – Penn State Erie
• Shannon Sweeney – Penn State Erie

Industry

• Ernie Ferro – Corry Rubber Company