Finite element-based force identification of sliding support systems: Part I—Theory

Sliding supports are widely used in bridges, space structures, and power plants to avoid potential damages to the structure due to expansion and contraction effects caused by temperature changes. To ensure the safety of an important structure with sliding supports, it is desirable to know both the magnitudes and positions of sliding forces through strain measurements. Effective and practical identification of sliding forces based on strain measurements on site is therefore explored in this paper. The problems involved in the force identification of sliding support systems are described. The finite element-based force identification technique and the strain measurement point selection procedure are then presented for the identification of sliding forces with no information required on their initial positions and magnitudes. The minimum strain measurement points with fairly good orthogonal property are targeted in the selection procedure. The quadratic programming problem with linear constraints and in some case the nonlinear least-squares method are involved in the identification of either concentrated sliding forces or uniformly distributed sliding loads. The feasibility and accuracy of the force identification technique and the strain measurement point selection procedure proposed in Part I of this paper will be demonstrated in Part II of this paper through numerical examples.