Experimental Research and Analysis on Encased Steel Box Concrete Beams

A encased steel box concrete beam (ESBCB) is light because it is hollow. In order to investigate the mechanical behavior of ESBCBs, 5 simple ESBCBs and 4 continuous ESBCBs have been tested. The test results reported include distribution of cracks, deformation, failure characteristics, strength and ultimate load. That the bending capacity of this kind of beam can be calculated in accordance with the plane section assumption was verified, and the formula for calculating crack width and stiffness are given. The formula for calculating the length of an equivalent plastic hinge for continuous ESBCBs is presented. A design method for moment modification is put forward, in which, the difference between the elastic calculated moment of critical section at the intermediate support and the moment subjected by the steel box is modified, and in the calculation formula, the variable is the relative plastic rotation.