Piotr Iwicki

Investigation of stability and limit load of a truss overhead opened bridge

The paper presents selected methods of determining stability and limit load of a truss top chord in opened bridges. These methods include linear buckling and non-linear static analysis based on the finite element method and algorithms based on design code procedures. The described methods were tested on an example of a steel footbridge situated in Straszyn. The results of stability analysis are compared. The results of geometrical and material non-linear analysis are close for the perfect structure, but very large (40%) for large imperfection amplitudes. Using first global free vibration mode as in initial imperfection resulted in greater load-carrying capacity than first global buckling mode. The critical forces is nearly equal to the results from non-linear analysis. A Polish standard procedure showed some difficulties during analysis so the final condition of stability was not satisfied, while a Eurocode procedure confirmed correctness of a footbridge design.

Bearing Capacity of Aluminum Bars with Built-Up Cross Section and Glued or Welded Connections

The paper is focused on numerical analysis and experimental test of aluminum bars with glued and welded connections between separate members. The connection properties were tested experimentally. The numerical analysis were conducted for the beam and shell model of the structure. The shape and magnitude of initial geometric imperfection was taken into account.

Analysis of Brace Stiffness Influence on Stability of the Truss

Abstract The paper is devoted to the numerical and experimental research of stability of a truss with side elastic supports at the top chord. The structure is a model of a real roof truss scaled by factor ¼. The linear buckling analysis and non-linear static analysis were carried out. The buckling length factor for the compressed top chord was calculated and the limit load for the imperfect truss shell model with respect to brace stiffness was obtained. The relation between brace normal force and loading of the truss is presented. The threshold stiffness of braces necessary to obtain the maximum buckling load was found. The truss load bearing capacity obtained from numerical analysis was compared with Eurocode 3 requirements.