Abstract
The study is concerned with normal-strength concrete corbels. 30 such corbels were studied by finite element modelling and the variables considered include ratios of primary and secondary reinforcement, type of applied loading, vertical or horizontal. Finite element modelling with a software package LUSAS was used to analyse four series of corbels namely PV series (primary reinforcement with vertical loading), SV series (secondary reinforcement with vertical loading), PH series (primary reinforcement with horizontal loading) and SH series (secondary reinforcement with horizontal loading). The results indicate that corbels with neither primary reinforcement nor secondary reinforcement fail suddenly. In the case of PV series and SV series, corbels increase in ratio of primary and secondary reinforcement generally resulted in enhancement of strength and ductility when subjected to only vertical loading. This increase is significant up to 0.4% in the case of primary reinforcement and 0.3% in the case of secondary reinforcements. No noticeable change in ultimate load or ductility was observed for corbels in PH series and SH series.
Highlights
A report on the 1964 Alaskan earthquake indicated that a substantial number of precast concrete structures distressed as a result of insufficient attention to their connections (Clottey 1977)
The cross-sectional area of secondary reinforcement varies from 0.0% to 0.45% and the models are analysed under the action of vertical loadings
The results show clearly that presence of additional secondary reinforcement resulted in an increase in loadcarrying capacity as well as in ductility of corbels
Summary
A report on the 1964 Alaskan earthquake indicated that a substantial number of precast concrete structures distressed as a result of insufficient attention to their connections (Clottey 1977). Connections in precast concrete construction, of primary members, form a critical part of the load-carrying and transfer mechanism. Because of the usually low shear span-to-effective depth ratio the loads are transferred predominantly through shear. The principal parameters influencing the structural response of reinforced concrete corbels are type (monotonic or cyclic) and direction (vertical or horizontal) of external loads, shear span-to-depth ratio, strength of concrete, shape and dimensions of corbels, grade and arrangements of longitudinal and transverse steel reinforcements (Kriz, Raths 1965; Mattock et al 1976; Yong, Balaguru 1994; Fattuhi 1994). Provision of secondary reinforcements reduces crack widths, improves ductility, changes failure mode from diagonal splitting to ductile (Fattuhi 1995)
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