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Li-Lin Cao,Ye-Jun Li,Manicka Dhanasekar,Chun-Hua Lu 대한토목학회 2021 KSCE Journal of Civil Engineering Vol.25 No.5
This paper presents a novel configuration of high strength U-shaped steel-encased concrete composite beam (HUCB) in which shear studs connect concrete and U-shaped steel at top flanges and bottom plate. The junction surface of upper slab and lower portion is strengthened by evenly distributed inserted circular rebar. Two steel reinforcements are arranged in the composite beam along the longitudinal direction to reduce the deformation of encased concrete and provide adequate bending capacity under fire condition. Based on the flexural experiments of five specimens, the test failure pattern, load-deflection relation curves, sectional strain distribution at different height and ultimate flexural performance of the HUCB were obtained and are reported in this research. The experimental results show that the HUCB has high ductility and excellent flexural performance. According to test results of five specimens, new calculation formulae were presented to theoretically analyze the flexural capacity of the HUCB. The theoretical analysis values of flexural capacity according to the proposed calculation formulae are consistent with the test results of all specimens. A three-dimensional finite element model is also established to investigate structural performance of the proposed novel composite beam. Test results of five specimens verify the accuracy and validity of finite element analysis results. Parametric studies of the HUCB under positive bending moment are carried out to further analyse the influence of concrete compressive strength, yield strength of U-shaped steel plate and flange width of concrete slab on the flexural performance of the proposed new composite beam.
Study on Coupled Vibration of Human-plate System under Pedestrian Excitation
Lilin Cao,Niankang Wang,Chun-Hua Lu,Manicka Dhanasekar 대한토목학회 2024 KSCE Journal of Civil Engineering Vol.28 No.4
In the paper, in order to explore the influence of human-structure interaction (HSI) in the vertical direction on the dynamic response of floors due to human-induced excitation, the formula for the human-plate interaction system is deduced. The pedestrian is in turn modelled as moving force (MF), spring-mass-damper (SMD), and added mass-spring-mass-damper (MSMD). The floor is modelled using a formulation in modal coordinates. Aiming at the formula of human-plate interaction system, the state space method is used to get the instantaneous frequency and instantaneous damping ratio of the floor under walking excitation, and the acceleration responses can be obtained using the Runge-Kutta method. Furthermore, this work studies the influence of pedestrian mass and structural modal mass on structural vibration response. The results show that the floor frequency is observed to decrease and the damping ratio gives the opposite trend when the pedestrian enters the floor. The MF model overestimates the measured response, while the actual results can be well approximated by the results for SMD and MSMD models considering HIS. Accounting for increasing human mass and decreasing modal mass lead to significant increase in the dynamic properties and the structural response.