Experiment and analyses on local compression bearing capacity of concrete in the case of Acor /Al <1.35 and Ab extending to side face of boundary beam

Abstract:

Experiments on local compression bearing capacity of 11 specimens were reinforced with the spiral indirect reinforcements with A cor /Al ranging from 0 to 1.316 and 12 specimens simulating prestressed concrete beams were anchored in the side face of boundary beam.The calculation method for local compression bearing capacity of concrete with A cor /Al < 1.35 was obtained.The contribution of indirect reinforcements to local compression bearing capacity in current code was multiplied by the reduction factor of strength of indirect reinforcements (λ).When A cor /Al < 1,the enhancement coefficient of local compression bearing capacity due to indirect reinforcements (β cor) equals to 1,and the net local compression area(Aln) in the indirect reinforcements contribution is replaced by the net concrete core area (A cor,n).λ relates to A b /Al and A cor /Al,and increases with the increase of the product of two ratios.It is presented that the side face of boundary beam can be taken as a part of local compression calculated bottom area according to current code,and the local compression bearing capacity can be calculated according to corresponding formulas,when the ratio of length of calculated bottom area outside the section of prestressed concrete beam to width of boundary beam is less than 2 and the width of boundary beam is larger than the shorter length of local compression area.