Experimental and Numerical Study of Steel Connections

Abstract

When analysing and creating steel frames structure, all connections are actually thought of as rigid or simple. From totally rigid to completely pinned, every realistic beam-to-column connection has some rotational stiffness. SR modelling of connections is hence more accurate. Designing and analysing framed constructions is significantly facilitated by assuming that the connections are stiff or properly fixed. The main index variables that affect a connection’s M-θ properties are its strength, rotational capacity and stiffness. In the present study, the classification strategy for connections given different Codes are studied. The study compared the behaviour of the 8 types of connections given in IS 800:2007 using the Frye-Morris Polynomial Model. As an illustration, a two-story, one-bay steel frame was employed. The SWA connection was discovered to be flexible, the T-stub connection to be rigid, and all other connections to be in between. To evaluate the effect of end plate thickness on FEP connection in steel connection under monotonic loading, a 3-D FEM is created in ABAQUS. The proposed model accounts for the contact between adjacent surfaces, material and geometrical non-linearities, and the pretension force on the bolts. The results of the FEA were compared with J.R. Ostrander’s experimental findings. Also, TSW-DWA connection was modelled in ABAQUS to obtained its M-θ curve which was compared with Atozod Azizinamini’s experiment and also FEM model for EEP connection was done in ABAQUS and comparison of all three connection is done with Frye-Morris mathematical model. In FEP connection effect of end plate thickness was anticipated. Using the methodology of J.R Ostrander, experimental set-up was prepared to obtain M-θ curve for FEP connection using ISMB 200 as column and ISMB 150 as beam with end plate thickness as 6mm with 10mm MS bolt and a ABAQUS model was prepared to compare experimental and analytically obtained curve. First experiment failed due to loss of contact of load cell and column. 2nd experiment was conducted by correcting the error and comparison of experimentally and analytically obtain moment rotation curve is done. The stiffness of the connections plays important role in forces, the lateral displacements of joints, and the base shear of the structure during earthquake events. The study aims to investigate the influence of the SR behaviour of the connection on the response of the frame structure. The moment-rotation relationship serves as a crucial indicator of the semi-rigidity of the connection. In this analysis, the SR connections are modelled as MLP link elements with kinematic hysteresis behaviour in SAP2000. Both rigid and SR connections are considered in the modelling of a 5-story steel Special Moment Resisting Frame (SMRF). The performance of the frame is evaluated through pushover analysis, comparing response parameters such as time period, lateral displacements, base shear, and inter-story drift ratio (IDR) between the rigid and SR connections. It is observed that lateral displacement decreases and base shear increases in SR connection Frame. Study of Ibarra Krawinkler model is done to implement the cyclic deterioration in moment-rotation curve. The study delves into the concept of a steel frame with hybrid connection pattern, which includes both semi-rigid (SR) and Rigid steel connections. The seismic performance of various patterns and placements of Semi Rigid connections is investigated on a 9-story SAC frame with four different ground motions i.e el centro, kobe, northridge and Hachinohe with three different intensities i.e 0.5,1 and 1.5. Nonlinear static pushover analysis (NSPA) is performed on the selected frames. The frames’ performance is assessed by using the maximum base shear and displacement as evaluation criteria. By adopting this hybrid method, both the lateral displacement and base shear are decreased compared to the original frame. The maximum Inter-story drift ratio of the hybrid frames is calculated and compared limits for limited strength (LS) and collapse prevention (CP) performance specified in FEMA 356.