title: Experimental and Theoretical Studies of Normal and High Strength Concrete Wall Panels with Openings
Creators: name: Lee, Dong-Jun
Publisher: name: Griffith University
Year: 2009
Subjects: subject: Concrete load bearing walls
subject: Reinforced concrete wall panels
subject: Layered finite element method

description: The simplified wall design formulae specified in the Australian (AS3600) and American (ACI318) concrete standards are intended for the design of normal strength concrete load bearing walls supported at top and bottom only. These practical codes fail to recognise any contribution to load capacity from restraints on all four sides, and do not provide recommendations and design equations for walls with openings (window and door). Also the current code methods are not applicable to the design of walls with high strength concrete (f’c&gt;65MPa) or high slenderness ratios (H/tw&gt;30). In many practical situations wall panels are restrained on all four sides and have openings. In other cases, high strength concrete walls may have reduced their thickness leading to a high slenderness ratio. The recognition and inclusion of such factors lacking in the current codes would result in more reliable and applicable design methods. A total of forty-seven (47) reinforced concrete wall panels were tested in the laboratory in three stages. Seventeen (17) walls with one and two openings in one-way action were tested in Stage one and eighteen (18) identical walls in two-way action were tested in Stage two. In the first two stages, the test panels had slenderness ratios between 30 and 40 and were of higher concrete strengths from 50MPa to 100MPa, and were subjected to a uniformly distributed axial load with an eccentricity of tw/6. In addition to highlighting the experimental set-up, typical crack patterns, failure modes, load- deflection behaviour and ultimate loads were also reported in some detail. Finally twelve (12) wall panels were tested in Stage three to investigate the behaviour of concrete wall panels with various opening configurations including wide window and door type with asymmetric location. The test panels had a constant slenderness ratio of 30 and a concrete strength of 65MPa. The same eccentric loading was applied and the panels were tested in both one- and two-way action. Utilising these test results, an empirical formula predicting the ultimate load of walls with openings was proposed. A favourable comparison between the predicted results and the test data (including the present and other experimental test results) indicates that the proposed formula is accurate and reliable for use in design. A numerical study was also undertaken to verify the effectiveness of the Layered Finite Element Method (LFEM) in predicting the failure characteristics of reinforced concrete walls with openings. The LFEM was used to model, six (6) normal strength concrete walls tested by Saheb and Desayi and thirty-five (35) concrete wall panels with openings tested in this research. The ultimate loads, load-deflection responses up to failure, deflected shapes and crack patterns predicted by the LFEM were compared favourably to the experimental observations. The comparative study also confirmed that the LEFM is a reliable and effective numerical modelling technique for determining ultimate load capacity of high strength concrete walls with high slenderness ratio and various opening configurations. Upon verification, the LFEM was then used as an effective tool to undertake three parametric studies, on a wide range of opening configurations, slenderness ratios and concrete strengths. The purpose of these parametric studies was threefold: (1) to provide missing data that were not covered by the code methods and existing empirical formulae due to their limited scope; (2) to conduct LFEM simulations which helped to reduce the number of labour intensive and very costly laboratory tests; (3) to validate the performance of the proposed formula in predicting the load carrying capacity of wall panels with openings. In total, 20, 64 and 108 wall models were analysed respectively for three parametric studies. The study confirms the accuracy and reliability of both the LFEM and the proposed formula. To this end, both the LFEM and the proposed formula can be used as an effective tool for the analysis and design of normal and high strength concrete walls with openings and high slenderness ratios performing in both one-and two- way action.