| Summary: | 碩士 === 國立成功大學 === 建築學系碩博士班 === 100 === Wing-walls and walls with openings are both incomplete panel within RC frames. In Taiwan, adding wing-walls is a popular seismic retrofit measure, but the wing-walls are usually modeled as columns but not panels in seismic analysis due to their slenderness. The analysis for walls with openings needs case-by-case consideration. It is too complicated so simplified methods such as reduction factors from the size of openings are usually used instead. These mean that practical models for both wing-walls and walls with openings are needed.
This research developed an analytical model to estimate the shear strength of RC wing-walls and walls with openings. The analytical model developed from shear-friction concept was originally used for RC shear walls without openings. It calculates the shear strength by simple force equilibrium of the walls with assumed failing path. When it is applied to walls with openings, the failing path must be modified due to the existence of openings. This research proposed the method to determine shear elements and failing paths for wing-walls and walls with openings. Two types of shear element configurations are suggested. The influence of varied axial force on failing path was discussed. However, the comparison with experimental data doesn’t show good result when the varied axial force is considered. Instead, an empirical method is proposed for determining the failing path.
Experimental result of 19 walls without openings, 60 walls with openings, and 19 wing-walls were used to verify the analytical model. The preliminary comparison with experimental result shows that the analytical model provides good and conservative estimation for the shear strength of wing-walls and walls without openings, but might be too conservative for walls with openings. Therefore, a revision for walls with openings was made from a detailed study on the errors. It is suggested that among the three modes of shear element-failing path combination proposed, mode A2 should be used when Fsv/Fsh ratio is lower than 2.5 and Mode B is used otherwise. The revised model is verified again and shows good result. Failure modes of the specimens were also compared with the analytical ones. The analytical failure mode is determined by the lesser of the analytical shear strength and flexural strength. The comparison shows accurate prediction for the walls without openings, slight error for walls with openings and conservative result for the wing-walls by mistaking flexural failure as shear failure.
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