Gilson Queiroz

Avaliação da segurança de vigas de alma senoidal sujeitas à flambagem lateral com torção - parte 1: requisitos básicos

There are no design standards or specifications dealing with all the phenomena involved in the structural behavior of corrugated-web beams. The development of recommendations that might express their behavior more properly, within the concepts and methods of the Theory of Reliability is therefore necessary. In this research, the safety assessment of sinusoidal-web beams for the lateral-torsioned buckling failure mode is performed. To this end, in this first part, the following basic requirements are presented: (i) proposal and validation of the calculation model; (ii) statistics of basic variables. The proposed model is based on an adaptation of the standards ANSI/AISC 360-05 (2005) and ABNT NBR 8800 (2008), in which the corrugated web is neglected on the computation of geometric properties. The statistics of basic variables were obtained from literature and measurements of the actual dimensions of sinusoidal-web shapes manufactured in Brazil.

Flambagem lateral com torção em vigas com perfis de alma senoidal

A Finite Element model was developed in order to study the behavior of beams with sinusoidal webs, subjected to Lateral Torsion Buckling, taking into account residual stresses and initial imperfections. The numerical model was validated by comparison with four experimental tests. To start the analysis of the model, a linear buckling analysis is made to find the first eigenvalue and the correspondent buckling mode. The next step is to assign the buckling mode to the geometrical model and the initial imperfection to the maximum mode displacement. Then an incremental plastic analysis is done, taking into account large deflections, until the model is unable to take on any other load increments due to physical or geometrical degeneration. Comparisons between numerical and experimental results are included. Comparisons between the results of eight numerical analyses and the correspondent provisions of a procedure based on the Brazilian code NBR 8800 (1986) are also included. For these eight comparisons 6 models were chosen to reach instability in the inelastic range and 2 in the elastic range. The sinusoidal web was ignored for the calculation of the geometrical properties.

Estimation of friction contribution in the behavior of steel-concrete composite beams with flexible shear connectors

A shear connector, developed to be applied to a composite beam whose steel profile is a thin-walled box profile, displayed much greater flexibility than the conventional welded shear connector, leading to particular issues in the composite beam behaviour. One of these issues is the role played by friction at the interface between the steel profile and the slab which, under particular circumstances, may be relevant for serviceability limit states and also for ultimate limit states. The Brazilian and American Standards do not yet recognize the friction contribution in the behaviour of composite beams, though they recognize this contribution in composite slabs. This paper presents the experimental tests carried out with and without friction contribution on simple supported composite beams with flexible connectors and the numerical models developed to simulate the behaviour of the tested beams. The experimental tests revealed significant increases in strength and stiffness of the composite beam due to friction contribution and the comparisons between numerical and experimental results displayed good correlations.

Avaliação da segurança de vigas de alma senoidal sujeitas à flambagem lateral com torção - Parte 2: análise de confiabilidade

There are no design standards or specifications dealing with all the phenomena involved in the structural behavior of corrugated-web beams. The development of recommendations that might express their behavior more properly, within the concepts and methods of the Theory of Reliability, is therefore necessary. In this research, the safety assessment of sinusoidal-web beams for the laterallytorsioned buckling failure mode is performed. In this second part, the reliability analysis of such elements, designed according to a procedure that incorporates the calculation model and the load and resistance factors, is performed. Herein, the following are presented: (i) the used reliability method; (ii) the performance functions; (iii) the reliability indexes implicit in the procedure. Based on the results, it is shown that the proposed procedure leads to reliable levels compared to those of plane-web shapes.