Nonlinear Seismic Performance Evaluation of Flexural Slotted Connection Using Endurance Time Method

Seyed Mohamad Seyed Kolbadi,S.Mahdi Seyed-Kolbadi,Ali Keyhani,Hosein Piri,Masoud Mirtaheri

doi:10.1155/2020/8842230

Abstract

The equivalent statistical methods, spectral analysis, and time history analysis are usually offered in the steel structure design regulations. Among these methods, the third one is more accurate; however, it requires more time to align the accelerometers due to a large number of analyses. In the endurance time (ET) method, incremental acceleration functions gradually and uniformly increases over time while their linear and nonlinear response spectra are proportional to the mean of the real seismic spectrum. These functions are used as input functions to analyze the nonlinear time history of structures, and the performance of structures is evaluated based on the maximum length of time they can meet specified performance goals. A three-story steel bending frame with (slotted web) SW and (web unslotted flange) WUF connection is examined through the performance time method in performance-based design. This article aimed at evaluating the seismic performance of these connections in the bending frame through endurance time analysis to predict the structural response in the probabilistic evaluation of the seismic performance of the structures. It is found that the endurance time analysis is justified with the seismic performance of the connections with low computational cost and proper accuracy. The results of comparing both SW and WUF connections indicated that the SW connection prevents the connection welding area from being failed due to transferring the plastic joint into the beam and in an area away from the column face and causes less damage compared to the WUF connection.

Highlights

After the 1994 Northridge earthquake [1] and the connection failure in the weld zone of the beam-to-column connection [2], the researchers sought to transfer the location of the plastic joint at a suitable distance from the column face [3]
Creating a groove in the beam web of the SW connection reduced the stress values in the column’s panel area. e results comparing the maximum strain in the beam-to-column connection area, fountain spring area, and the modelled frames are shown in Figure 15, where PEEQ strain and MISES stress are used
(ii) Using the SW connection compared to the WUF connection reduces the maximum amount of table tension in the panel area after dynamic loading in 15 seconds by 20.9%, while in the same period, table tension in the weld zone of the beam-to-column connection is reduced by 6.6%

Summary

Introduction

After the 1994 Northridge earthquake [1] and the connection failure in the weld zone of the beam-to-column connection [2], the researchers sought to transfer the location of the plastic joint at a suitable distance from the column face [3]. Seismic collapse refers to the inability of structural systems to resist under gravitational loads or shortly after an earthquake [7]. The equivalent degree of freedom (SODF) was used by several researchers to predict initial collapse [10,11,12]. This method is very good for understanding the problem, it is not reliable enough to be used as a tool to assess the collapse capacity of structures. Using the single degree of freedom (SDOF) exhibits nonlinear behaviour when the structure is approaching the stage of collapse which does not have an appropriate answer [10]. Attempts have been made to estimate IDA results through pushover analysis [17, 18]; the accuracy of these methods at this level of approximation requires a simple analytical method, which results in a comprehensive analysis of the behaviour of the structure from the beginning to the complete collapse of the structure [19]

Methods

Results

Conclusion