dc.description.abstract | 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. | |