采用力控制加载的拟动力试验等效力控制方法

Pseudo-dynamic tests with effective force control method based on force-loading control strategy

等效力控制方法是求解非线性微分方程的隐式积分方法,可很好地应用到拟动力试验中。但是这种方法是基于位移控制加载提出的,对于大刚度结构拟动力试验,采用位移控制加载试验将难以进行,为此提出了力控制加载模式下的等效力控制方法。通过设计一个反力分配系数,使得加载设备采用力控制模式工作,并且采用比例-积分控制器实现等效力的反馈控制。理论分析和数值模拟表明,该方法是一种无条件稳定、无需数值迭代求解的数值积分方法;当选取了合适的控制器参数时,就能消除控制系统的稳态误差。试验结果证明,对于大刚度结构拟动力试验,采用力控制加载得到的试验结果要比采用位移控制得到的结果准确。研究表明,该方法可以很好地应用到大刚度结构拟动力试验中。

Effective force control method （EFCM） is an implicit integration method to solve nonlinear differential equations, which can be well used in pseudo-dynamic （PSD） tests. However, PSD tests with this method adopting displacement-loading control strategy usually are difficult to carry out if the speeimen is too stiff, then a new EFCM using force-loading control strat- egy is presented in this paper. A force distribution coefficient was designed in the proposed new method to make the loading de- vices work in force-loading control mode, and a proportional-integral controller was used here to achieve the equivalent force feedback control. Theoretical analysis and numerical simulation show that the proposed method is unconditional stable and re- quires no iteration; the steady-state error can be eliminated if the proper eontroller parameters were chosen. It is found that test results obtained by force-loading control will be more accurate than those obtained by displacement-loading control for the spec- imen with large stiffness. This paper shows that this new method can be successfully applied to PSD tests of structures with large stiffness.