Ghaemdoust Mohammad Reza, Wang Feiliang, Li Siping, Yang Jian
State Key Laboratory of Ocean Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
Shanghai Key Laboratory for Digital Maintenance of Buildings and Infrastructure, School of Naval Architecture, Ocean and Civil Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
Materials (Basel). 2021 Apr 28;14(9):2273. doi: 10.3390/ma14092273.
This paper deals with the effect of the prestress load on the free and forced dynamic behavior and vertical vibration of the prestressed beams. The analysis applies both the analytical frequency equation and the finite element method (FEM) using ABAQUS software to predict the fundamental natural frequency (FNF) of the simply supported unbonded prestressed beams. The energy method has been employed to derive the effective prestressing load to determine the eccentricity effect. In regard to the forced response of the prestressed beam, a moving point load with a constant value and various velocities and excitation frequencies is applied. Extensive parametric studies are carried out taking into account different factors including prestress load, eccentricity, concrete ratio, span-to-depth ratio, velocity, and frequency of the moving load. The comparison of the FNFs obtained by the formula with those obtained from FEM models indicates that the results are in a good agreement. This convergence demonstrates that the proposed formulation can predict the FNF of the eccentrically prestressed beams with high reliability. The time-histories curves for midspan displacement of the unbonded prestressed beams and the dynamic magnification factors are also evaluated. The results illustrate that the aforementioned factors have an indispensable contribution to the beam dynamic behavior.
本文研究了预应力荷载对预应力梁的自由和强迫动力特性以及竖向振动的影响。分析采用解析频率方程和使用ABAQUS软件的有限元方法（FEM）来预测简支无粘结预应力梁的基频。采用能量法推导有效预应力荷载以确定偏心效应。对于预应力梁的强迫响应，施加了具有恒定值以及不同速度和激励频率的移动点荷载。考虑了包括预应力荷载、偏心距、混凝土比例、跨高比、移动荷载的速度和频率等不同因素，进行了广泛的参数研究。通过公式得到的基频与有限元模型得到的基频的比较表明结果吻合良好。这种一致性表明所提出的公式能够高度可靠地预测偏心预应力梁的基频。还评估了无粘结预应力梁跨中位移的时程曲线和动力放大系数。结果表明，上述因素对梁的动力特性有着不可或缺的影响。
