title: Experimental and Theoretical Studies on Three-side Restrained Reinforced Concrete Walls
Creators: name: Ho, Nhat Minh
Publisher: name: Griffith University
Year: 2018
Subjects: subject: Reinforced concrete walls
subject: Cracking characteristics
subject: Load-deflection
subject: Ultimate strengths
subject: WASTABT
subject: ABAQUS
subject: Rigid-plastic method
subject: Hybrid-system method

description: Cast in situ or precast reinforced concrete (RC) walls are commonly used in multistorey buildings to withstand gravitational and lateral loadings. Walls restrained along the top and bottom edges by floors, with free vertical edges, subjected to in-plane axial loads behave in one-way action (OW). Axially-loaded walls can also behave in two-way action with lateral support on three sides (TW3S) or four sides (TW4S), formed by floors and intersecting walls, when they are combined to form an isolated box, a bundled box, a coupled core, or a geometric, U-, T- or L-shape. In many circumstances, walls are pierced with openings because of architectural requirements or functional modifications of the structures. However, these openings are a source of weakness and can size-dependently reduce the stiffness and load-bearing capacity of the structure. RC walls subjected to eccentric axial loads can be designed using simplified design methods, provided in major codes of practice, which include, inter alia, the Eurocode 2, the Australian Concrete Standard and the American Concrete Institute Code. However, these code methods do not take into consideration the design of high slenderness wall panels. There is also little guidance in the design codes for walls with openings. With the current advancement in construction materials and technologies, significant cost savings and increases in the net leasable space of a building may be achievable through the design and use of thinner walls. It is thus becoming increasingly important to carry out less conservative and more relevant designs for structural wall elements. Although numerous studies have been undertaken on OW and TW4S walls with and without openings in an effort to better understand the structural behaviour of such walls and further improve their design models, studies on TW3S walls have not been conducted to the same depth. There is a lack of fully comprehensive research on the behaviour of axially-loaded TW3S walls with and without openings, design models for high slenderness TW3S walls with various aspect ratios and design models for TW3S walls with openings. Consequently, there is a need for further studies on TW3S walls with and without openings, which is the focus of this thesis. Given little prior information in the literature on the behaviour of TW3S walls, comprehensive experimental and numerical studies were conducted in this research. A total of 18 wall panels, consisting of 10 solid panels and eight panels with an opening, subjected to a uniformly-distributed axial load at an eccentricity of one-sixth of the wall thickness, were constructed and tested at Griffith University, Gold Coast campus. The influences of several key parameters on the axial load capacity of TW3S wall panels were examined. These parameters included slenderness ratio, aspect ratio and the configuration and position of the openings. The axial load behaviour of the test specimens was studied with regard to cracking characteristics, load-deflection responses and ultimate strengths. Numerical investigations were undertaken by means of a computer program, WASTABT, and commercial finite element software ABAQUS. Specifically, WASTABT was written in the MATLAB programming package to execute an instability analysis for TW3S solid walls (proposed in this research), and the all-encompassing program ABAQUS was used to perform numerical analysis of both TW3S solid walls and TW3S walls with openings. Having established that these numerical programs satisfactorily predicted the experimental outcomes, extensive parametric studies were then carried out to investigate the effects of key parameters on the axial load capacity of full-scale TW3S walls. Particular emphasis was given to the effects of varying the slenderness ratio, aspect ratio, concrete strength, load eccentricity and reinforcement ratio, in addition to the configuration and position of the openings. A number of quantitative conclusions were drawn from the studies, which both enhanced the fundamental understanding of, and provided insight into, the behaviour of axiallyloaded TW3S walls with and without openings. In view of the shortcomings of the code design equations and the scarcity of other available models to estimate the ultimate strength of TW3S walls with and without openings, a set of design models, covering a broader spectrum of designs, was developed in this research. The research focused on the development of simplified design equations, and a rigid-plastic method for TW3S walls with and without openings, along with a hybrid-system method for solely TW3S walls with openings. Comparisons with the test data of the current and previous studies, in addition to the numerical results of WASTABT and ABAQUS, confirmed that the proposed models are satisfactory and reliable, and thus, can serve as useful design aids for engineering applications.