Limit load analysis of the lateral support framework for an ice condenser system

In the paper, limit analysis of the lattice framework is conducted for three principle load conditions: radial, tangential, and radial+tangential. Depending on the load pattern, the analysis is formulated as a linear programming problem based on either the static or kinematic theorem of plastic collapse. In view of the size and complexity of the lattice frame, decomposition theory is employed to reduce the various problems to the smallest size possible. Multiple stress resultants affecting plasticity are considered, and corresponding piecewise linear yield surfaces are generated also using mathematical programming techniques. A general computer programme is employed for all analyses. Given the nature of the loads and the structure properties, the programme generates yield surfaces and formulates and solves the limit analysis in one operation. The critical load pattern is identified as having the smallest limit load level. With a view to improve the accuracy of the solution, the limit analysis for this load case is repeated several times for increasingly refined yield surface approximations. The final analysis results concerning limit load(s) and plastic collapse mode(s) entirely confirmed the previously obtained results from experimental tests and elastic analysis. The limit load levels for all load cases were found to be in excess of the minimum qualification loads established by applying load factors to the primary functional design loads, thereby conclusively demonstrating the structural integrity of the lattice frame support system