Subjects: Civil Engineering and Building Construction >> Civil Construction Structures submitted time 2023-11-11
Abstract： This report summaries the current status about the design of the structures rigidly connected with weak sky corridor, followed by studying in details the theoretical issues involved in the structural analysis associated with the estimation of torsion performance of the connected structures and cracking and stiffness deterioration of the connecting slabs, which are concerned by structural engineers.
In this report, taking deformation characteristics of the weak connecting slab as a key point, the basic principles of damage mechanics are applied to conduct a detailed and in-depth study on the stress redistribution between the concrete and steel, as well as between the concrete slab and supporting steel gird due to the damage evolution and deterioration of elastic modulus of the damaged concrete. Adopting the contrary thinking according to phenomenology, a suggestion of reducing the elastic stiffness including the flexural, shear and axial stiffness as the effective stiffness by the macroscopic stiffness reduction factor R is put forward, to reflect the microscopic concrete damage effects. Thus, a practical design method is proposed, by using the equivalent elastic time history analysis of a 3D model, in which each tower has its own rigid diaphragm and the connecting slab is flexible with reduced stiffness to effectively realize the above-mentioned stress redistribution.
Through a typical engineering example of the weak slab with reduced effective stiffness of the sky corridor connecting structures presented here, the report authors’ energy and ductility-based concept of the seismic design is elaborated in detail. The results of the equivalent elastic time history analysis of the example show that it is unreasonable to completely neglect the concrete contribution to the structural system combined with the reinforced concrete connecting slab and the steel truss, verify the effectiveness of the above practical design method which adopts the equivalent elastic time history analysis to assess the torsional performance of the connected structures and realize the redistribution of the internal forces due to the stiffness deterioration of the reinforced concrete connecting slab, which results in a substantial reduction in the steel quantity of the connecting truss.
In response to the phenomenon of assigning "zero stiffness" to connecting slab, which is widely adopted currently in design, the theoretical insights and recommendations in this report are inspirational and realistic meaningful to improve the design method as well as economic and technical indicators.
Peer Review Status:
Awaiting Review
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