Behaviour and modelling of partial‐strength beam‐to‐column composite joints for seismic applications

Abstract

A refined component model is proposed to predict the inelastic monotonic response of exterior and interior beam-to-column joints for partial-strength composite steel-concrete moment-resisting frames. The joint typology is designed to exhibit ductile seismic response through plastic deformation developing simultaneously in the column web panel in shear, the bolted end-plate connection, the column flanges in bending and the steel reinforcing bars in tension. The model can handle the large inelastic deformations consistent with high ductility moment-resisting frames. Slip response between the concrete slab and the beams was taken into account. A fibre representation was adopted for the concrete slab to accurately capture the non-uniform stress distribution and progressive crushing of the concrete at the interface between the concrete slab and the column flange. The model is validated against results from full-scale subassemblages monotonic physical tests performed at the University of Pisa, Italy. A parametric study is presented to illustrate the capabilities of the model and the behaviour of the joints examined. Concrete crushing Re-bars yielding Shear yielding Flexural yielding Flexural yielding Gap opening Figure 1. Partial strength beam-column joint studied: (a) configuration; and (b) deformed configuration.structures typically exhibit relatively higher lateral stiffness which permits to more easily satisfy code specified drift limits. Compared to traditional steel structures, more effective beam-to-column joints can also be obtained by making use of the contribution of the concrete slab for resisting bending moments due to gravity and lateral loads [1]. Furthermore, these structures can be built with partial-strength partially restrained beam-to-column joints designed with ductile components that can deform in a ductile manner in case of a strong earthquake. In the common case where beam sizes are governed by drift or alike design criteria, rather than flexural strength requirements, ductile partial strength connections allow the formation of a desirable beam hinging global frame mechanism, with large hysteretic energy dissipation capacity and reduced force demand on the columns [2]. The possibility of using partial strength connections as the main energy dissipative mechanism for the seismic resistance of frames has now been recognized in modern design codes [3][4][5].The behaviour of this type of structures heavily depends on the connection response and a significant portion of the research effort on steel-concrete composite frames with partial-strength beam-to-column joint has been devoted to the development of connection systems and the study of their behaviour under seismic and cyclic loading [6][7][8][9][10][11][12][13][14][15][16][17][18][19]. In the framework of two jointed European research projects [20][21][22], a partial-strength beam-to-column joint was proposed for moment resisting frames with partially encased composite columns in which energy dissipation is provided by both the column web panel z...

Seismic Performance of High-Rise Steel MRFS With Outrigger and Belt Trusses Through Nonlinear Dynamic Fe Simulations

“…Additionally, a detailed approach is currently almost unfeasible if the response of an entire mega-frame system has to be investigated. By contrast, the complex contribution of bolted [22][23][24][25][28][29][30] and welded [20,21,31,32] joints can be easily incorporated into classical fiber-based FE models, able to represent the interaction among connection components in an equivalent manner. Thus, mechanical representations have been assumed in this research to include global response and potential failure mechanisms of these systems, as discussed later on.…”

Seismic performance of a 3D full‐scale high‐ductility steel–concrete composite moment‐resisting structure—Part I: Design and testing procedure

“…Well-proportioned column panel zones exhibit stable hysteretic shear response with significant strain hardening behaviour [4,31]. The potential for ductile and robust performance of connections with energy dissipation shared between the beam end-plate and the column panel zones was demonstrated for PS joints with structural steel columns [4,8].…”

“…Global beam hinging mechanisms for earthquake resistance can be achieved at a reduced cost as the force demand on joints and columns is governed by the expected capacity of the ductile connection components rather than by the beam flexural capacity. The behaviour of such a framing system heavily depends on the joint response and a significant part of past research on steel-concrete composite PS frames was devoted to the development of connection details able to behave in a ductile manner under cyclic inelastic loading [3][4][5][6][7][8][9][10]. Numerical studies were also performed to verify the global seismic performance of partially restrained (PR) composite frame structures [11][12][13].…”

Dissipating Effect of Glazed Curtain Wall Stick System Installed on High-Rise Mega-Braced Frame-Core Buildings Under Nonlinear Seismic Excitation

“…Prospective buckling mechanisms in both braces and gusset plates were considered applying an out-of-plane imperfection equal to 0.1% of the length at its midspan. Similarly, according to [12,14,15,16,18,39,40,42], the Tstub bolted joint mechanical idealization was assumed to reproduce the hysteresis behavior, as a partially restrained connection. Accordingly to the Grant and Priestley paradigm [41], when considering the tangent stiffness-proportional Rayleigh damping, the stiffness-proportional matrix multiplying coefficient used to perform nonlinear dynamic analyses was correlated to the damping ratio associated to the fundamental period of the structure [38,41,42,43].…”