مطالعه عددي اتصالات برشي پيچي اصطكاكي با قابليت بازنصب تحت بارگذاري چرخه‌اي

Abstract Shear connections play a fundamental role in transferring shear forces an‎d ensuring composite action between steel beams an‎d concrete slabs in composite structures. Although welded headed stud connectors are widely used, their permanent nature makes the separation an‎d reuse of structural components difficult. In contrast, demountable bolted shear connections provide composite action while offering several advantages, including rapid an‎d convenient installation, the possibility of dismantling an‎d reinstalling precast concrete slabs, improved repairability, an‎d greater compatibility with sustainable construction principles. However, knowledge of the nonlinear an‎d cyclic behavior of these connections remains limited, an‎d further investigation is required to develop reliable design provisions. In this study, the cyclic behavior of demountable bolted shear connections between precast concrete slabs an‎d steel members was investigated using the finite element method an‎d ABAQUS software. The numerical model considered the nonlinear behavior of concrete, steel, an‎d bolts, bolt pretension, contact an‎d friction between the connection components, an‎d slip between the concrete slab an‎d steel member. For validation, the numerical force–slip hysteresis curves an‎d envelope curves were compared with the experimental results. The comparison showed that the numerical model could adequately predict the shape of the hysteresis curves, load-bearing capacity, initial stiffness, slip corresponding to peak load, strength degradation, an‎d energy dissipation of the connection. Following validation, a parametric study was conducted considering five main variables: bolt pretension, compressive strength of concrete, clearance between the bolt an‎d the concrete hole wall, bolt diameter, an‎d bolt strength grade. The responses of the models were eva‎luated using force–slip hysteresis curves, envelope curves, an‎d performance indicators such as load-bearing capacity, slip corresponding to peak load, initial stiffness, stiffness degradation, ductility, strength degradation, an‎d energy dissipation, an‎d were compared with the reference model. The results showed that bolt diameter had the greatest influence on the load-bearing capacity of the connection, whereas bolt-to-hole clearance an‎d bolt pretension played more significant roles in controlling slip an‎d the initial behavior of the connection. Increasing the compressive strength of concrete improved the local resistance around the hole an‎d enhanced the connection capacity; however, its influence diminished at higher concrete strengths. Increasing the bolt strength grade also improved the resistance of the connection, although its effect on load-bearing capacity was more limited than that of bolt diameter. Furthermore, variations in the investigated parameters affected the shape an‎d area of the hysteresis loops, thereby changing the energy dissipation of the connection. Overall, the validated numerical model proved to be a suitable tool for investigating cyclic behavior, eva‎luating energy dissipation, an‎d identifying the parameters governing the performance of these connections.

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معصومه

168271