Experimental and numerical investigations of axially loaded RC walls restrained on three sides

Abstract

Axially loaded reinforced concrete (RC) walls in tilt-up structures can be supported top and bottom only by floors or roof structures. However, RC walls are often combined to form I-, C-, T-, and L-shapes to make efficient use of the building area in multi-storey buildings. With these configurations, walls may also be laterally supported on either or both sides by interconnecting walls. While many researchers have investigated the behaviours of RC walls, either in one-way action or two-way action supported on four sides with and without openings, limited research has been conducted on two-way action walls supported on three sides (TW3S). As such, this paper experimentally and numerically investigates the behaviour of TW3S walls. Details of the 12 half-scale walls tested, including experimental setup, failure loads, crack patterns, and load-deflection characteristics, are reported. In addition, the Finite Element Method using ABAQUS software for investigating the behaviour of TW3S walls is described in detail. Finally, due to the conservative nature of code design equations and there being limited available methods for predicting the ultimate load of TW3S walls with openings, a rigid-plastic approach has been proposed in this study to evaluate the failure load of TW3S walls. KEYWORDS aspect ratio, axial load, concrete walls, openings, slenderness ratio, yield line | INTRODUCTIONReinforced concrete (RC) walls have been commonly used as load-bearing elements in buildings and offshore structures. Primary applications include tilt-up precast structures, shear walls in multi-storeyed buildings, lift core walls in high-rise buildings, components in bridge construction such as webs of beams or box girders, storage cells in offshore concrete structures, and parts of floating concrete structures such as barges and pontoons. [1] In general, typical loadings on RC walls are in-plane loads, consisting of gravitational and shear forces, and out-of-plane transverse loads. In-plane vertical loads are frequently eccentric, causing a pronounced out-of-plane curvature owing to a range of loading conditions including corbel elements applied to the wall face, imperfections in construction, uneven loading being experienced on top of the wall, and temporary loading during operation and/or maintenance. [2] Walls can be constructed with various support conditions. Walls restrained top and bottom only by floor plates, with free vertical edges, are usually encountered in tilt-up concrete structures. Such walls behave in one-way (OW) action depicted by uniaxial curvature in the direction of loading, as shown in Figure 1(a). In practice, walls behaving in two-way action supported on three sides (TW3S) and supported on four sides (TW4S), provided by floor plates and stiffening walls, or other sufficiently stiff members, are usually encountered in monolithic concrete structures, particularly in core walls of tall buildings. These panels generally deform along both the horizontal and vertical directions, as outlined in Figure 1(b-c). As a resul...

Prediction of ultimate strength of concrete walls restrained on three sides

“…To observe the effects of aspect ratio ( H w / L w ) and slenderness ratio ( H w / t w ) of TW3S walls closely, the axial strength ratios ( N u / f' c L w t w ) of test data, including the current test failure load points and the test results from previous research, were plotted against these parameters (Figures and ). The failure lines, predicted by the EC2 and AS3600 equations, were also plotted in these figures.…”

“…In an effort to undertake a comparison study with experimental results from previous research, six one‐third to one‐half scale wall panels with various slenderness ratios ( H w / t w ) and aspect ratios ( H w / L w ) were cast and tested to failure.…”

“…All panels were cast horizontally in purpose‐made timber molds with minimum central reinforcement ( ρ v = ρ h = 0.31%). A single F41 mesh centrally placed within the panel cross section allowed the elements to be treated as unreinforced elements, with no contribution to their capacity from the steel reinforcement . The primary purpose of minimum wall reinforcement detailing was to control cracking due to shrinkage and temperature stresses.…”

“…The average compressive strength of the concrete utilized for the panels was determined by standard‐sized concrete cylinders cured under the same moist‐curing condition beside the panels. The geometric and material properties of the test panels (and those conducted by Doh et al and Ho and Doh) are given in Table .…”

“…Although numerous studies have been undertaken on OW walls and TW walls supported on four sides (TW4S walls), in an attempt to better understand the structural behavior of such walls and to further improve their design models, the performance of TW walls supported on three sides (TW3S walls) has not been investigated to the same depth and there is little research published in this area. Apart from a number of tests carried out by Doh et al, and more recently by Ho and Doh, there has been a lack of fully comprehensive research on the axial load capacity of TW3S walls, and of design models for high slenderness TW3S walls with various aspect ratios. Consequently, there is a need for further studies on TW3S walls, which is the focus of this paper.…”