NUMERICAL AND THEORETICAL STUDIES ON DOUBLE STEEL PLATE COMPOSITE WALLS UNDER COMPRESSION AT LOW TEMPERATURES

Double steel plate composite walls (DSCWs) with several unique types of connectors have been implemented to protect offshore oil exploration platforms from concentric forces caused by ice in the Arctic region. This paper investigates the compressive perfor-mance of DSCWs with interlocked J-hooks and overlapped headed studs at low temperatures ranging from 20 ℃ to -80 ℃ with nonlinear finite element models (FEMs). The intricate geometric size of the concrete, multiple interactions of the concrete with the connectors, and material nonlinearities of the concrete have been thoroughly simulated. The reasonable consistency between the results of the monotonic tests and finite element analysis (FEA) on nine DSCWs with interlocked J-hooks and seven DSCWs with overlapped headed studs indicates that the FEMs can effectively predict the compressive performance of the DSCWs at low temper-atures. On the basis of the validated FEMs, the effects of the horizontal and vertical spacing of the connectors on the compressive performance of the DSCWs are studied. Finally, theoretical models of the load-displacement curves are developed to reveal the compressive response of DSCWs at low temperatures with different types of connectors, taking into account the restraining effect of steel plates on the inner concrete and the local buckling of steel plates. Compared with previous tests and FEA, the developed theoretical models have reasonable consistency for the load-displacement curves of DSCWs at low temperatures.

Numerical Analysis of the Structural Resistance and Stability of Masonry Walls with an AAC Thermal Break Layer

Since energy efficiency has become the main priority in the design of buildings, load-bearing walls in modern masonry constructions nowadays include thermal break elements at the floor–wall junction to mitigate thermal bridges. The structural stability of these bearing walls is consequently affected. In the present paper, a numerical study of the resistance and stability of such composite masonry walls, including AAC thermal break layers, is presented. A finite element mesoscopic model is successfully calibrated with respect to recent experimental results at small and medium scale, in terms of resistance and stiffness under vertical load with or without eccentricity. The model is then used to extend the numerical models to larger-scale masonry walls made of composite masonry, with the aim of investigating the consequences of thermal elements on global resistance and stability. The results confirm that the resistance of composite walls is governed by the masonry layer with the lowest resistance value, except for walls with very large slenderness and loaded eccentrically: composite walls with low slenderness or loaded by a vertical load with limited eccentricities are failing due to the crushing of the AAC layer, while the walls characterized by large slenderness ratios and loaded eccentrically tend to experience buckling failure in the main clay masonry layer.

A Fibre-Based Modelling Technique for the Seismic Analysis of Steel-Concrete Composite Shear Walls

Steel-concrete composite shear wall offers a favourable lateral strength and deformation ductility for seismic applications while significantly shortening the project schedule through eliminating the use of formworks and taking advantage of modular construction methodology. This paper presents a fibre-based modelling technique for simulation of the cyclic nonlinear response of composite walls by taking advantage of existing reinforced concrete and steel plate shear wall models. The improved modelling technique for cyclic analysis of composite walls that benefits from the macro models available for steel and concrete shear walls is introduced. The model is validated using experimental test data from 20 wall specimens. A sensitivity analysis is performed to examine the influence of various geometrical and material properties using the proposed modelling technique. A step-by-step modelling recommendation is finally proposed. The results show that the proposed modelling technique can efficiently be used to reproduce the nonlinear cyclic response of composite walls.