NONLINEAR PRESTRESS OF SPACE CABLE NET STRUCTURES

Abstract

Cable-net structures are used for many structural purposes, such as stadiums, roofs, bridges…etc. They are lightweight structures that can be used in unique construction at an effective cost. Geometrical nonlinearity governs the performance of cable net systems. This particular system can equilibrate applied loads by undergoing significant deformations with small strains. Therefore, the cable-net structures require to attain a suitable degree of prestressing to prevent cables from slacking and to obtain specific geometry and function. The effective numerical approach is applied for computing the desired level of prestress for a three-dimensional cable-net model and a conical cable-net model. The targeted prestress is achieved considering the nonlinear behavior of cables. The nonlinear member variation is introduced as a second-order function of displaced joints. Then used in determining the desired prestress. Two numerical examples are conducted using the present technique and the nonlinear analysis of SAP2000. Both of the analysis outcomes for the models showed a very well agreement with reaching the target. However, using the Euclidean norm index with a value of 0.0809 in the first example confirmed that the current technique is more approachable to the desired prestress. In addition, when the value of actuation is pre-determined and used in computing the degree of prestress, both the present approach and SAP2000 software work equivalently, as seemed in the second example, which showed 0.04% of the maximum difference in the prestress computation.

Keywords

• cable-net; prestress; geometric nonlinearity; self-equilibrate; force method