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Using the steel strongback braced (SB) system to seismically strengthen and retrofit reinforced concrete moment frames (RCMFs), this research aims to enhance the effectiveness of RCMFs. In this study, RCMFs of 5-, 10-, and 15-stories were designed according to the first and fourth editions of the Iran Earthquake Standard 2800. The RCMFs designed for the first edition are strengthened and reinforced using the strongback braced system. The studied structures were analyzed under incremental static loading and time history analysis. The findings indicate that the yield force and maximum base shear of structures designed using the fourth edition have increased by a range of 1.28–1.42 compared with those designed with the first edition. This underscores the imperative to enhance the structural integrity of buildings constructed according to the first edition. Meanwhile, the results of retrofitted structures with strongback braces show the same or better performance than newly designed structures. This indicates that this retrofitting system has a favorable effect on uniform drift control. A reduction of 33%–44% in story drift was observed when the SB system is added to the first edition's structure. [ABSTRACT FROM AUTHOR]

In the last few decades, the idea of using thin steel plate shear walls (SPSW) as a resistant system against lateral loads in designing and reinforcing buildings has been of concern to researchers and designers. In this research, we studied the response modification coefficient (R), the overstrength factor (Ω0), and the deflection amplification factor (Cd) in a reinforced concrete special moment frame (RC-SMF) with thin SPSW. We used the performance-based plastic design (PBPD) method. For this purpose, we consider frames with SPSW systems with different story numbers. Static pushover analysis is performed on these frames using the strip model in OpenSees software. OpenSees software is the Open System for Earthquake Engineering Simulation located at http://opensees.berkeley.edu. Simulation results were compared with experimental results, and acceptable matching was observed between the two. Finally, the values of response modification coefficient (R), overstrength factor (Ω0), and deflection amplification factor (Cd) for RC-SMF with thin SPSW were calculated based on the Uang method. The ultimate limit design method proposed them as 9.37, 2.21, and 11.06. [ABSTRACT FROM AUTHOR]

Structures are subjected to a variety of environmental and loading conditions over time, and minor damage to structural elements may occur. By timely identifying damage and repairing damaged locations, it is possible to prevent the spread and development of damage to other elements and, as a result, the overall destruction of the structure. This article discusses the identification and determination of the location of damage in steel plates based on the use of the primary and secondary shapes of vibration modes and the analytical method of two-dimensional wavelet analysis. Modelling and frequency analysis of the plate were performed in ABAQUS software, and the primary and secondary mode shapes were extracted. To determine the location of the damage, a damage detection index (DDI) was proposed based on the angle between the primary and secondary mode shape vectors and the diagonal detail coefficients obtained from the wavelet analysis of the primary and secondary mode shapes. The results showed that by using this index, damage can be identified by identifying peaks resulting from irregularities and disturbances. Also, the DDI value of the damage was dependent on the severity of damage occurring in a damaged situation, and the height of the disorder peaks increased with increased damage only at that damage position. [ABSTRACT FROM AUTHOR]