Experiment on Static Behavior of Segmental Precast PC Cap Beam

Abstract:

In order to investigate the static performances of segmental prefabricated large-cantilevered PC cap beams with different epoxy joints under the combined action of bending and shear internal forces， an integral precast large-cantilevered PC cap beam model and 3 segmental prefabricated large-cantilevered PC cap beam models with large key teeth， small key teeth and corbel joints respectively （the scale of each model is 1：5） were designed and manufactured based on a practical engineering. The full-process static loading tests of the four models were conducted， and the key results such as cracking loads， ultimate load capacities， distributions of concrete strains， deflections， and maximum crack widths of the cap beams were obtained. The test results show that： the crack distributions of the segmental prefabricated models are basically the same as that of the integral prefabricated model， and cracks in the cap beams of all test models are sparse and wide during failure； the failure modes of all test models are flexural failure； the cracking load of the cap beam model with large key teeth or corbel joint is the same as that of the integral cap beam model， while the cracking load of the cap beam model with small key teeth joint is only 81% of that of the integral cap beam model； the ultimate bearing capacities of the cap beam models with different epoxy joints are significantly lower than that of the integral cap beam model； among segmental precast models， the ultimate bearing capacity of the cap beam model with corbel joint is the largest， which is about 84% of that of the integral cap beam model； in terms of ultimate deformation capacity， the ultimate displacement of the cap beam model with corbel joint reaches 75% of that of the integral cap beam model， while the ultimate displacement of the model with large or small key teeth joint is lower than 50% of the integral cap beam model. From the test results of static performances and construction performance， the corbel joint is a more reasonable epoxy joint recommended for segmental prefabricated large-cantilevered PC cap beams.

Key words:Urban bridge;Segmental precast;Prestressed concrete cap beam;Epoxy joint;Cracking load;Ultimate bearing capacity