On the deflection of composite reinforced steel truss-concrete beam under static and dynamic load

Abstract

In this study, a test beam model of negative moment region was designed to study its deflection characteristics under over-limit static load and variable amplitude cyclic load scenarios. (1) According to the deflection test results of the test beam under over-limit static load, the load-deflection curve under static load before and after 10000 times of over-limit fatigue load tended to sharply increase in the first place and then slow down afterwards. At the ultimate load, the maximum deflection value of the two was 8.625 mm and 8.76 mm, respectively. The maximum deflection value after 10000 times of over-limit fatigue load increased by 1.57% compared with that before. (2) The deflection test results of the test beam under variable amplitude cyclic load showed that both the total deflection and the residual deflection percentage increased firstly and decreased with the increasing fatigue load times. The total deflection ranged from 4.07–4.3 mm, and the residual deflection percentage was 0.1–1.65%; The residual deflection percentage reached a maximum of 1.65% when the fatigue load times reached 2 million. (3) The deflection test results of the test beam under over-limit variable amplitude fatigue load showed that the maximum residual deflection reached 0.08 mm (maximum residual deflection percentage 1.75%), 0.11 mm (maximum residual deflection percentage 2.30%), 0.16 mm (maximum residual deflection percentage 2.65%) after 1.5, 2 and 3 times over-limit variable amplitude fatigue load was imposed respectively. The maximum deflection did not fluctuate obviously, indicating that the test beam was had sound working performance. (4) In this study, the shear stiffness and fatigue load times were fully considered, the mean value of the ratio of the deformation value to the measured value of the test beam was 0.89, and the standard deviation was 4.86%. When the fatigue load times exceeded 2.8 million, the ratio of the calculated value to the measured value was less than 0.85. In conclusion, the model had its own limitations.