SHEAR STRENGTH MODEL FOR HIGH-STRENGTH LIGHTWEIGHT AGGREGATE CONCRETE DEEP FLEXURAL MEMBERS

According to the test results due to the action of a concentrated load for eight simply supported deep flexural members whose shear span to depth ratios and span-depth ratios are 0.26~1.04 and 2, as well as 3, respectively, and made of LC40 high-strength lightweight aggregate concrete under, the failure process and failure pattern of this kinds of deep flexural members are analyzed emphatically. The shear capacity model is established, based on softened strut-and-tie model for high-strength lightweight concrete deep flexural members. The model is used to calculate the shear strength of these 24 members, the results of which have been compared with the results accepted from the shear formulas suggested by current design codes, GB50010-2010, ACI318-08, CSA and EC2. Results shows that the failure pattern for high-strength lightweight concrete deep flexural members could be divided into shear failure and flexure-shear failure, and its shear capacity is controlled by concrete diagonal strut. The results of softened strut-and-tie model approach to the data from tests, and agree with the results of the current codes. But the softened strut-and-tie model has a definite mechanical model and can reasonably reveal the failure mechanism of deep flexural members.