Effect of Converting Connections to Moment-Resisting on the Seismic Retrofit of Existing Steel Structures

Gerami, Mohsen; Rostamian, Ali; Jadidi, Ali

doi:10.22034/jcema.2025.237277

Effect of Converting Connections to Moment-Resisting on the Seismic Retrofit of Existing Steel Structures

https://doi.org/10.22034/jcema.2025.237277

Volume 9, Issue 4
Autumn 2025

Pages 191-200

Journal of Civil Engineering and Materials Application

Document Type : Original Article

Authors

Mohsen Gerami ¹

Ali Rostamian ²

Ali Jadidi ²

¹ Faculty Member, Faculty of Civil Engineering, Semnan University, Semnan, Iran.

² PhD Student, Structural Engineering, Faculty of Civil Engineering, Semnan University, Semnan, Iran.

Abstract

Converting beam-to-column connections to moment-resisting connections can be considered as a retrofit strategy for various steel structural systems, including moment frames, braced frames, and mixed (dual) systems. Welded Flange Plate (WFP) connections are rigid beam-to-column connections in which steel plates are welded to the beam and column flanges to provide flexural strength and stiffness. In this study, an existing five-story steel building was evaluated under a vertical expansion scenario (adding stories up to nine). First, the structure was modeled in ETABS as an intermediate moment-resisting frame (IMRF) in the X direction combined with a special concentric braced frame (SCBF) in the Y direction. Next, an alternative model with the same geometry and member sizes was developed, in which the connections in the moment-frame direction were replaced with WFP rigid connections, resulting in a dual system. Member checks and acceptance evaluations were performed using the Iranian guideline for seismic retrofit of existing steel buildings (Publication 1-363). The results indicate that, for the 7-, 8-, and 9-story configurations, stiffening the connections increases the number of braces that satisfy the acceptance criteria; approximately 50% of the braces that did not meet the acceptance criteria in the simple-frame system satisfy the criteria after connection stiffening in the dual system.

Keywords

Seismic retrofit

steel structures

WFP connections

adding stories

existing structures

Subjects

Structural Engineering

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