Research

We conduct integrated experimental and numerical research toward low-damage high-performance earthquake-resilient building systems. 

We aim to reduce the sensitivity of the buildings' seismic response to the variability of the characteristics of the earthquake ground motions. 

We look forward to working with industry partners to enhance the two way transfer of knowledge between practice and research.

This project aims to develop a simple and practical structural connection with predetermined discrete variable friction forces at target design displacements.

The team is grateful for financial support provided by University of California San Diego. Any opinions, findings, and conclusions expressed in this research are those of the authors and do not necessarily reflect the views of others acknowledged here. 

This project aims to validate the Alternative Design Provisions for Diaphragms per ASCE 7-22 Section 12.10.3 utilizing the strong-motion data recorded from a set of selected instrumented buildings that are actively monitored. It also aims to assess the effect of the second mode and higher mode responses in the selected instrumented buildings to validate their absolute and relative importance in the seismic response of buildings.

The research team acknowledges to the California Strong Motion Instrumentation Program for their support through the project called “Validation of Seismic Design Provisions for Diaphragms and Assessment of Higher-Mode Responses on Earthquake-Resistant Buildings” and to the Chilean National Agency for Research and Development (ANID) for their support through the foreign doctoral scholarship 2020. The authors also acknowledge to Mehmet Çelebi, PhD, PE and Lisa S. Schleicher, Ph.D., Geophysicist, both part of the USGS, for facilitating the data required to replicate the results given in Şafak and Çelebi (1990). Any opinions, findings, and conclusions expressed in this paper are those of the authors and do not necessarily reflect the views of others acknowledged here. 

Core wall system is a popular seismic force-resisting system for tall buildings. However, tall core wall buildings have large participation of higher mode response in the total dynamic response which amplifies the floor acceleration and story shear forces. One way to mitigate the higher mode effect is using force-limiting connections. Force-limiting connections allow the movement of the gravity load-resisting system (GLRS) relative to the seismic force-resisting system (SFRS) and limit the seismic-induced horizontal forces transferred between the two systems.  

Force-limiting connections have been developed for planar wall buildings. These force-limiting connections consist of a friction device and low-damping rubber bearings (i.e., FD+RB). This study assesses the seismic response an eighteen-story building with force-limiting connections that are modified (i.e., Modified FD) to accommodate the three-dimensional kinematics in core wall buildings. Three-dimensional earthquake numerical simulations of an eighteen-story core wall building model are performed.

Numerical simulation results show that Modified FD force-limiting connections can be used in core wall buildings to reduce the magnitude and variability of the seismic-induced shear, torsional and acceleration responses of the building while maintaining a reasonable relative displacement between the GLRS and the SFRS. The Modified FD force-limiting connections also reduce the magnitude and variability of the maximum and minimum strain demand in the core wall base.

The team is grateful for financial support provided by University of California San Diego. Any opinions, findings, and conclusions expressed in this research are those of the authors and do not necessarily reflect the views of others acknowledged here. 

This project focused on the seismic response of a 9-story self-centering steel concentrically braced frame with force-limiting deformable connections between the floors and the braced frame designed using a force-based method.

The team is grateful for financial support provided by Lehigh University and the Advanced Technology for Large Structural Systems (ATLSS) Engineering Research Center. Any opinions, findings, and conclusions expressed in this research are those of the authors and do not necessarily reflect the views of others acknowledged here. 

This project proposed a force-based design method for force-limiting deformable connections that are used to transfer seismic-induced horizontal forces from the floor-diaphragms in buildings to the vertical elements of lateral seismic force-resisting systems with base flexural mechanisms (e.g., reinforced concrete shear walls). The design method determines the limiting forces for the connections at each floor of the building. The limiting forces for the connections are the forces at which the force-limiting deformable connections transition from linear-elastic to post-elastic response. The proposed design method is a modified version of the ASCE/SEI 7-16 alternative seismic design force method for floor-diaphragms. Design examples are presented. Seismic responses from numerical simulations of twelve-story, eight-story, and four-story reinforced  concrete shear wall example buildings show that the proposed method enables effective preliminary design of the force-limiting deformable connections. It is shown that the buildings with connections designed with the proposed method have relatively uniform distribution of connection deformation demands over the building height. It is also shown that their seismic force and acceleration responses have reduced magnitude and reduced variability compared to conventional buildings that exhibit large variability in their acceleration responses.

The team is grateful for financial support provided by Lehigh University and the Advanced Technology for Large Structural Systems (ATLSS) Engineering Research Center. Any opinions, findings, and conclusions expressed in this research are those of the authors and do not necessarily reflect the views of others acknowledged here. 

This research is based upon work supported by grants from the National Science Foundation, award no. CMMI-1135033 in the George E. Brown, Jr. Network for Earthquake Engineering Simulation Research (NEESR) program and award no. CMMI-0402490 for the George E. Brown, Jr. Network for Earthquake Engineering Simulation (NEES) consortium operations. Georgios Tsampras is grateful for additional financial support provided by the Gerondelis Foundation, Yen Fellowship, and Lehigh University. The contributions of Dr. Joe Maffei, Mr. David Mar, Dr. Shivaglal Cheruvalath, and the NEES@Lehigh and ATLSS Center staff are acknowledged. The authors appreciate the contribution of the companies DYMAT™, Star Seismic® (currently a CoreBrace company), and Scan-Pac Mfg, Inc. 

For the shake-table tests additional support was provided by the Prestressed/Precast Concrete Institute (PCI), the Charles Pankow Foundation, PCI West, Clark Pacific, and the “Fund of Social Development” grant (№КФ-14/03) at the Nazarbayev University. Material and device donations provided by industry partners Star Seismic, MMFX, Davis Wire, DYMAT, JVI Inc., Pleiger Inc., Wire Reinforcement Institute, FYFE, BASF Inc., Gerdau Inc., HRC Inc., Core Slab, Dura Fiber, and Triton Structural Concrete. Engineering and construction services provided by industry partners Midstate Precast, T.B. Penick & Sons, Brewer Crane & Rigging, Atlas Construction Supply, Western Concrete pumping, and Steel City Scaffold. The research team members are grateful for this support. 

Any opinions, findings, and conclusions expressed in this research are those of the research team members and do not necessarily reflect the views of the National Science Foundation or others acknowledged here.