Shear Bearing Capacity of Ultra-High Performance Concrete Keyed Joints Based on Shear-Compression Strength Criterion

To find out the shear bearing capacity and its calculation method of ultra-high performance concrete (UHPC) keyed joints, a full-scale model test of five UHPC keyed joints and a UHPC flat joint were carried out with the joint type and lateral compressive stress as parameters. The failure mode and the variation of shear bearing capacity of the specimens with UHPC joint were studied. Then, based on the shear-compression strength criterion of concrete, the octahedral stress formula was used to derive the formula for calculating the shear bearing capacity of UHPC keyed joints, which was then validated by the test results. Finally, the experimental data of 62 UHPC keyed joints were collected and used to verify the accuracy of the developed formula. The results show that the UHPC keyed joint is damaged by vertical major cracks developed at the root of the keys and has obvious brittle characteristics. The ultimate load of the specimen with an epoxied joint is greater than that with a dry joint by 21.3% under the same lateral compressive stress. When the lateral compressive stress increases from 3 MPa to 12 MPa, the ultimate load of the specimen with an epoxied joint increases by 26.9%. The developed formula can accurately predict the shear bearing capacity of UHPC keyed joints with low dispersion and conservative results in general. The average absolute errors of the specimen with five keyed joints are 11%, and those of 62 existing specimens are 21%.