PEER Reports

PEER Reports

Stochastic Dynamic Analysis of Bridges Subjected to Spatially Varying Ground Motions, PEER Report 2011-105

Katerina Konakli
Armen Der Kiureghian
2011

Using response spectrum and time-history analysis methods, we perform a thorough investigation of the response of bridges subjected to spatially varying support motions. Three main causes of spatial variability are considered: the incoherence effect, which represents random differences in the amplitudes and phases of seismic waves due to reflections and refractions that occur during wave propagation in the heterogeneous medium of the ground and due to differential superposition of waves arriving from different parts of an extended source; the wave-passage effect, which...

The Use of Base Isolation Systems to Achieve Complex Seismic Performance Objectives, PEER Report 2011-06

Troy A. Morgan
Stephen A. Mahin
2011

One concern in the design of base isolated structures is the selection of isolation system properties so that optimal performance is achieved over a range of seismic levels and performance metrics. To withstand very rare ground motions, isolation bearings are frequently designed with significant strength or damping, and as a result such devices provide reduced isolation effect for more frequent seismic events. To investigate possible improvements to the design of isolated
structures, an extensive research program is conducted. Analytical and experimental investigations are presented to...

Water Supply in regard to Fire Following Earthquake, PEER Report 2011-08

Charles Scawthorn
2011

A major earthquake in Los Angeles, San Diego or the San Francisco Bay Area is expected to result in numerous fires. A survey of fire and water agencies (with responses from those serving about one third of urbanized California) found poor understanding of the post-earthquake fire issue, and poor communication between fire and water agencies on this issue. In order to mitigate this problem, it is recommended that meetings should be held within the California fire service and the California water distribution community, to highlight this problem and enlist both communities in an effort to...

Earthquake Engineering for Resilient Communities: 2011 PEER Internship Program Research Report Collection, PEER Report 2011-10

Heidi Faison
Stephen A. Mahin
2011

Recent earthquakes in the United States and around the world have repeatedly shown that earthquake resilience is essential to building and sustaining urban communities. Earthquake resilience will play an increasingly important role in the professions associated with earthquake hazard mitigation, thus there is a need to educate the next generation of these professionals. To address this need, the Pacific Earthquake Engineering Research Center (PEER) coordinates a summer internship program for undergraduate students that focuses on the theme of earthquake-resilient communities. With funding...

Mechanics of Fiber Reinforced Bearings, PEER Report 2012-101

James M. Kelly
Andrea Calabrese
2012

The report contains the findings of a study on the mechanical behavior of unbonded fiber-reinforced bearings (FRB). Typical FRBs consist of several layers of rubber that are bonded to fiber reinforcing sheets. The purpose of the reinforcement is to prevent the rubber from bulging laterally under compressive load. The most important aspects of these bearings are (i) they do not have thick end plates; (ii) they are not bonded to the top and bottom support surfaces; and (iii) their reinforcements are very flexible. These aspects may seem to be design deficiencies, but they have the advantage...

Procedure to Restart an Interrupted Hybrid Simulation: Addendum to PEER Report 2010/103, PEER Report 2012-102

Vesna Terzic
Bozidar Stojadinovic
2012

A hybrid simulation can be intentionally or unintentionally interrupted. This document describes a procedure to restart an interrupted hybrid simulation. The restart of an interrupted hybrid simulation involves restoration of the state of the hybrid model to the state at the beginning of time step at the point at which the interruption occurred (the interrupt time step). Then the hybrid simulation from this point continues and the time steps until the planned simulation break or end occurs. The state of the hybrid model comprises the state of the hybrid simulation integrator (the outer...

Performance-Based Seismic Demand Assessment of Concentrically Braced Steel Frame Buildings, PEER Report 2012-103

Chui-Hsin Chen
Stephen A. Mahin
2012

The highly nonlinear behavior associated with buckling and nonductile fracture of braces reduces the ability of the special concen trically steel braced frame (SCBF) system to dissipate energy, resulting in undesirable modes of behavior. We analyzed archetype buildings of SCBFs and buckling restrained braced frames (BRBFs). The seismic demands of the system and structural elements were computed and interpreted for 3-, 6-, and 16-story SCBFs and BRBFs under various hazard levels. The analysis results show large seismic demands for the 3-story SCBF, which may result in unexpected damage of...

Seismic Performance of Reinforced Concrete Bridges Allowed to Uplift during Multi-Directional Excitation, PEER Report 2012-02

Andres O. Espinoza
Stephen A. Mahin
2012

The behavior of bridges subjected to recent moderate and large earthquakes has led to bridge design detailed for better seismic performance, particularly through wider bridge foundations to handle larger expected design forces. Foundation uplift, which is not employed in conventional bridge design, has been identified as an important mechanism, in conjunction with structural yielding and soil-structure interaction that may dissipate energy during earthquakes. Preventing uplift through wider foundations looks past the technical and economic feasibility of allowing foundation uplift during...

Experimental and Analytical Studies on Reinforced Concrete Buildings with Seismically Vulnerable Beam-Column Joints, PEER Report 2012-03

Sangjoon Park
Khalid M. Mosalam
2012

Existing reinforced concrete (RC) buildings de signed prior to the 1970s are vulnerable to shear failure of beam-column joints under earthquake excitations because of insufficient transverse reinforcement in the joint region. The failure of such “unreinforced” joints, especially corner joints, has played a crucial role in building collapses in past earthquakes. The accurate prediction of shear strength and flexibility for these unreinforced beam-column joints is therefore essential to assess the seismic risk of older-type RC buildings characterized by having unreinforced beam-column joints...

Shake Table Tests on a Shallow Foundation on Liquefiable Soils Supported on Helical Piles, PEER Report 2021-07

Milad Jahed Orang
Ramin Motamed
2021

Extensive damage to buildings and infrastructure observed during past earthquakes resulting from the liquefaction of shallow saturated soil deposits underneath structures has demonstrated the necessity for further research in the area of liquefaction-induced ground movement effects. This study explores utilizing helical piles as a countermeasure to reduce liquefaction-induced foundation settlement and investigates their seismic performance in liquefiable grounds. Two large-scale shake table test series, one without any mitigation measures and one using helical piles, were conducted using...