Design for Lateral Loads/Systems

Single Abstract

341828 - The Concept and Application of Post-Tensioning Systems for Retrofitting Existing Steel Moment Connections

Friday, April 20
11:00 AM - 12:30 PM
Location: 202B

To reduce the economic cost of repairing steel frames after a severe earthquake, application of self-centering methods has been investigated to bring back structures to their initial position after experiencing plastic deformations. According to the analytical and experimental results of this study, locally post-tensioning of beam-to-column connections enhances the seismic performance of existing steel frames as an innovative and interesting topic for structural engineers in any locations with a high seismic demand. During this presentation, the concept of self-centering is explained to practical structural engineers using a schematic physical model. Moreover, the design procedure of fabricating the specimens for an experimental test is provided. Furthermore, the effect of different connection parameters in the moment-rotation response is shown and summarized in an analytical equation which is interesting for researchers and code developers as the other target audiences of this presentation.
Attending this presentation, the audiences will be able to use what they have learned in this presentation as follow:
Using a simplified physical model in this presentation helps the practical engineers to better understand the construction procedure of the proposed retrofitting method and the effect of post-tensioned strands in providing a self-centering capability. The effective parameters in assigning the restoring moment applied by the strands are discussed using this scaled model. The similar type of teaching tools can help faculties to teach the concept of this study to students.
The construction detail of applying post-tensioning strand and anchoring them for retrofitting an existing steel moment connection with top and seat angles is explained using the accomplished experimental test approach of this study. Structural engineers can use the same procedure for anchoring high strength steel strands behind the column flange and the stiffeners which are welded to the beam section close to the connection zone.
The code developers and design engineers can refer to the experimental test results and the simplified analytical equation that is developed in this study to calculate the moment-rotation envelope for retrofitted connections under cyclic loading. The experimental test results show increases in the ultimate strength, rotation stiffness, and self-centering capability of the retrofitted connections.
The post-tensioning strand length and the loss of strands force because of strand and anchorage seating are two important parameters that are studied in this study. Structural engineers who are interested in post-tensioned structures can use the analytical equations in this study to account for these parameters for more accurately analyzing and designing post-tensioned connections.

Sepehr Movaghati

Ph.D. Candidate
University of Memphis

A Ph.D. candidate in structural engineering with published journal and conference papers.

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Adel E. Abdelnaby

Assistant Professor
University of Memphis

Abdelnaby holds a Ph.D. from the University of Illinois at Urbana-Champaign (2012). He has been on the faculty of the Department of Civil Engineering at The University of Memphis since the fall of 2012. His professional experience includes working as a design engineer at ACE Consulting Engineers Moharram-Bakhoum, one of the largest construction and civil engineering companies in the Middle East. Dr. Abdelnaby's research interests are primarily in the areas of structural dynamics, earthquake engineering, structural health monitoring, life-cycle analysis of structures subjected to multiple hazards, application of innovative and smart materials in structures for hazard mitigation, passive and active control of structures, and nonlinear finite element methods. He teaches graduate and undergraduate courses related to the behavior and design of steel structures, nonlinear analysis of structural systems, and mechanics of materials.

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