Citation: Gajbhiye, P.D.; Mashaan, N.S.; Bhaiya, V.; Wankhade, R.L.; Vishnu, S.P. Inelastic Behavior of Steel and Composite Frame Structure Subjected to Earthquake Loading. Appl. Mech. 2023, 4, 899–926. https://doi.org/10.3390/ applmech4030047 Received: 23 May 2023 Revised: 5 July 2023 Accepted: 25 July 2023 Published: 16 August 2023 Copyright: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). Article Inelastic Behavior of Steel and Composite Frame Structure Subjected to Earthquake Loading P. D. Gajbhiye 1 , Nuha S. Mashaan 2, * , V. Bhaiya 3 , Rajan L. Wankhade 4, * and S. P. Vishnu 3 1 Department of Civil Engineering, Sardar Vallabhbhai National Institute of Technology, Surat 395007, India; gparam786@gmail.com 2 School of Engineering, Edith Cowan University, Joondalup, WA 6027, Australia 3 Civil Engineering Department, Sardar Vallabhbhai National Institute of Technology, Surat 395007, India; vishisht@amd.svnit.ac.in (V.B.); greenhutvishnu@gmail.com (S.P.V.) 4 Applied Mechanics Department, Government Polytechnic, Bramhapuri 441206, India * Correspondence: n.mashaan@ecu.edu.au (N.S.M.); rajanw04@gmail.com (R.L.W.) Abstract: Steel construction is used more often these days as an alternative to the R.C.C. when lightweight, high-strength, large-span structures with a faster erection are required. Extensive studies have been conducted by researchers to study the seismic performance of reinforced concrete and steel structures, both in terms of elastic and inelastic behavior. Composite construction is also a recent advancement in the building industry with similar advantages. However, no emphasis has been given to the comparison between the inelastic behavior of steel and composite structures when subjected to lateral loads. This study compares the inelastic behavior of steel and a composite frame designed to have the same plastic moment capacity for structural members. The responses, such as the formation of hinges, story drifts, story displacements, lateral stiffness, ductility, maximum strength, energy dissipated, joint accelerations, and performance points, are compared with the aid of the building analysis and design software ETABS-18. For this, response spectrum analysis, pushover analysis, and nonlinear direct integration time history analysis have been performed on both frames. For design and analysis, international codes, such as IS 800-2007, IS 875 (Part I, II, IV), IS 1893-2002, AISC 360 (16 and 10), and FEMA 440, have been used. Part of this study also aims at comparing the response of these frames when subjected to near-field and far-field earthquakes. It can be concluded from the results that the post-yield performance of the composite frame is superior to that of the steel frame when seismically excited. Keywords: direct integration time history analysis; response spectrum analysis; pushover analysis; near-field earthquake; far-field earthquake; ETABS 1. Introduction Composite in the construction industry is a word that refers to the usage of steel, reinforced concrete, and composite steel–concrete components in combination with one another. Mixed or hybrid systems are a contemporary trend in the building sector. These structures maximize the structural and economic advantages of each component type by optimizing their usage. Thorough research is presently being performed to have a better grasp of how such frames operate. On the other hand, a beam–column combination has long been known for its better earthquake protection and has become a popular building method. In light of the growing popularity and usage of such systems, frame analysis is required. Additionally, nonlinear analysis is a strong tool for better understanding system behavior, especially when dynamic excitation occurs. Available analytic programs are capable of simulating the behavior of typical steel or composite structures. In the past, powerful earthquakes have caused major property damage and fatalities. Earthquake damage is primarily related to seismically weak buildings, which were frequently constructed prior to the adoption of modern building rules. As a result, academics have concentrated their Appl. Mech. 2023, 4, 899–926. https://doi.org/10.3390/applmech4030047 https://www.mdpi.com/journal/applmech