Performance Evaluation of Negative Stiffness Devices for Seismic Response Control of Bridge Structures via Experimental Shake Table Tests

29 Jul 2014 | Contributor(s): Navid Attary, Michael Symans, Satish Nagarajaiah, Andrei M Reinhorn, Michael Constantinou, Apostolos Aristotelis Sarlis, Dharma Theja Reddy Pasala, Douglas Taylor

A newly developed passive device that provides negative stiffness has been implemented within a quarter-scale highway bridge model and subjected to seismic loading via shake table testing. Details of the experimental results and their comparison with numerical simulations under a wide range of...

Optimal nonlinear damping for MDOF inelastic structures

29 Jul 2014 | Contributor(s): Jian Zhang, Wang Xi

Supplemental energy dissipation in the form of nonlinear viscous dampers is often used to improve the performance of new structures or to retrofit the existing ones. The role of the nonlinear damping is function of structural properties, the ground motion characteristics and the performance...

Optimal Design of Isolation Devices for Buildings Using Performance Based Methodology

29 Jul 2014 | Contributor(s): Jian Zhang, Zhan Shu

Seismic isolation is a viable method to reduce seismic damages to buildings under moderate and severe earthquake events. In order to systematically evaluate and optimize the building responses, this paper develops and applies the performance-based analysis and design methodology to assess the...

Dimensional Analysis of Inelastic Structures with Negative Stiffness and Supplemental Damping Devices

29 Jul 2014 | Contributor(s): Zhan Shu, Jian Zhang, Satish Nagarajaiah

Negative stiffness device (NSD) has been proposed as an innovative devices for seismic protection of structures. It has been shown numerically and experimentally that they can improve the performance of inelastic structures when they are appropriately designed for the given application. In order...

Seismic Responses and Protection of Building Systems Using PBEE Methodology

29 Jul 2014 | Contributor(s): Zhan Shu

Buildings are vulnerable to earthquake ground motions. To help reduce the loss from earthquake events, seismic protective devices emerged in recent decades to improve the performance of building structures against earthquake loads. The ultimate goal of this research is to explore new devices...

Seismic Protection of Highway Bridges with Negative Stiffness Devices

29 Jul 2014 | Contributor(s): Navid Attary, Michael Symans, Satish Nagarajaiah, Andrei M Reinhorn, Michael Constantinou, Apostolos Aristotelis Sarlis, Dharma Theja Reddy Pasala, Douglas Taylor

Technical Report MCEER-13-0013:A new control device has been developed and implemented for seismic response control of highway bridges. The device produces negative stiffness in a completely passive manner via a mechanical mechanism. Numerical simulations and experimental shaking table tests have...

Dynamic Lateral Stability of Elastomeric Seismic Isolation Bearings

29 Jul 2014 | Contributor(s): Venkata Vemuru, Satish Nagarajaiah, Armin Masroor, Gilberto Mosqueda

Predicting the response of elastomeric seismic isolation bearings when subjected to severe ground motions is challenging due to the highly nonlinear behavior associated with the bearings under a combination of large displacements and axial loads. In particular, the horizontal stiffness of the...

Enhanced Smooth Hysteretic Model with Degrading Properties

29 Jul 2014 | Contributor(s): Tathagata Ray, Andrei M Reinhorn

The elastic and inelastic nonlinear behavior of structural members use constitutive relations in which restoring forces and deformations are not proportional, and often follow different paths in loading and unloading using hysteretic functions. There are numerous available models that can trace...

Adaptive Stiffness Shaping using Negative Stiffness Device and Apparent Weakening for Seismic Response Control of Multi-story Buildings: Novel Distributed Isolation

29 Jul 2014 | Contributor(s): Satish Nagarajaiah, Dharma Theja Reddy Pasala

“Apparent weakening” of structures using the negative stiffness device (NSD) is a new passive structural control approach developed by the authors to mitigate the response of structures during severe ground motions. Experimental studies on a SDOF inelastic system bolstered the idea and confirmed...

Simulated Bilinear-Elastic Behavior in a SDOF Elastic Structure using Negative Stiffness Device: Experimental and Analytical Study

29 Jul 2014 | Contributor(s): Dharma Theja Reddy Pasala, Apostolos Aristotelis Sarlis, Andrei M Reinhorn, Satish Nagarajaiah, Michael Constantinou, Douglas Taylor

The acceleration and base shear of structures during strong ground motion can be attenuated by achieving bilinear-elastic behavior without any permanent displacement—also referred to as “apparent weakening.” The negative stiffness device (NSD), used in this study, exhibits nonlinear-elastic...

Direct In - Situ Evaluation of Liquefaction Susceptibility

29 Jul 2014 | Contributor(s): Julia Roberts

M.S. Thesis describing in great detail the work completed at WLA in March 2012. Includes background information, testing procedures, analysis procedures, results, and recommendations for future work.

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29 Jul 2014 | Contributor(s): Lily Dong

3D Unit Cell Model of Prefabricated Drain in Liquefiable Soil

29 Jul 2014 | Contributor(s): Rachelle Howell, Xiaoyue Wang, Ellen M. Rathje

This OpenSees model is a 3D unit cell infinite slope model of the area of influence around a single drain (or, in the case of the untreated model, a free-field untreated area equal to the area of influence around a single drain). It was developed to simulate lateral spreading in the in-plane...

Benchmark Wireless Structural Control Problem

29 Jul 2014 | Computational Models | Contributor(s): Zhuoxiong Sun, Bo Li, Shirley Dyke, Chenyang Lu, Lauren Linderman

Structural control systems offer an attractive approach to protect civil infrastructures from natural hazards such as earthquakes. Wireless structural control systems which utilize wireless sensors for sensing, communication and control have drawn increased attention due to the flexible...

Performance Based Implementation of Seismic Protective Devices for Structures

29 Jul 2014 | Publications | Contributor(s): Wang Xi

In order to improve the seismic performance of structures and to reduce the total cost (both direct and indirect) due to earthquake damages, structural control through seismic protective devices in either passive or semi-active forms is essential to achieve the desired performance goals. This...

Verification of Real-Time Hybrid Simulation with Shake Table Tests: Phase 1 – Modeling of Superstructure

29 Jul 2014 | Publications | Contributor(s): Ali Irmak Ozdagli, Wang Xi, Yong Ding, Jian Zhang, Shirley Dyke, Bin Wu

In the last few decades, base isolation has become a recognized strategy for mitigating earthquake damage in civil engineering structures. To increase reliability and adaptability of these passive devices, semi-actively controllable magnetorheological (MR) fluid dampers can be introduced as a...

Verification of Real-Time Hybrid Simulation with Shake Table Tests: Phase 2 – Development of Control Algorithms

29 Jul 2014 | Publications | Contributor(s): Ali Irmak Ozdagli, Shirley Dyke, Wang Xi, Jian Zhang, Yong Ding, Bin Wu

In the last few decades, structural control has become a recognized strategy for mitigating earthquake damage in civil engineering structures. Within structural control, magnetorheological (MR) fluid damper is acknowledged as a promising method. In order to broadly evaluate the performance of MR...

Pipe Liners Undergo Initial Seismic Test

22 Jul 2014 | Notes | Contributor(s): Marti LaChance

ASCE Civil Engineering | July 22, 2014 | Online news

New structural system could help concrete bridges withstand earthquakes

16 Jul 2014 | Notes | Contributor(s): Marti LaChance

ASCE Smartbrief | July 16, 2014 | Weekly newsletter for ASCE members

New Concrete Bridge Bent System may Minimize Seismic Damage

15 Jul 2014 | Notes | Contributor(s): Marti LaChance

ENR.com Engineering News-Record  | July 7, 2014 | Magazine, online magazine