Shear Behavior of Large-Scale Deep Beams with Lightweight-Aggregate Concrete

摘要

Fifteen lightweight-aggregate concrete (LWAC) deep beams subjected to symmetric concentrated loading were tested for the study of shear behavior and size effect. The test variables include beam depths (h ranged from 500 to 1400 mm [19.7 to 55.2 in.]), shear span-depth ratios (a/h = 0.75, 1.00, and 1.50), and bearing plate widths (130 and 200 mm [5.12 and 7.88 in.]). The test results showed that all specimens failed in shear-compression mode. As a/h increased, the specimen failure gradually occurred more gently. Additionally, the bearing plate width had a slight influence on the crack pattern of the specimens. The normalized shear strength at failure decreased by approximately 37.1% when h increased from 500 to 1400 mm (19.7 to 55.2 in.), indicating remarkable size dependence. The accuracy and applicability of four current codes and two size-effect models were then verified by the test results. A comparison study revealed that the ACI 318-14 code and Tan-Cheng's model are more accurate in predicting the size effect on the shear strength of LWAC deep beams, while estimations from AASHTO LRFD are over-conservative for specimens with an a/h of 1.5.