Gerson Moacyr Sisniegas Alva

Análise não-linear de estruturas de concreto armado em procedimentos de projeto: emprego de modelos de dissipação concentrada

This paper deals with the utilization of lumped dissipation models in the nonlinear analysis of reinforced concrete structures for design procedures, particularly those that deal with material nonlinearity in structural analysis. The main purpose of this paper is to compare the results obtained from the theoretical model with the results obtained from other types of structural analysis, including the simplified proce- dures recommended by NBR 6118 to consider the effects of material nonlinearity. Based on two numerical examples of ultimate limit state verification, some advantages and limitations of the lumped dissipation models in real situations of design are discussed.

Engastamento parcial de ligações viga-pilar em estruturas de concreto armado

This paper presents the results of experimental tests on reinforced concrete beam-column connections carried out at the Engineering School of Sao Carlos - USP. The experimental results concentrate on relative rotations between beam and column, which are importante parameters for the evaluation of the moment-rotation curves and the characterization of semi-rigid behavior of the connections. The experimental results were obtained from tests on specimens of edged beam-column connections. The influence of concrete compressive strength and joint transverse reinforcement ratio on relative rotations was investigated. The experimental results were compared with results obtained from the theoretical model proposed by Ferreira [1] for partially restrained connections, which provided an evaluation of the percentage of restriction obtained by the types of monolithic connections considered in this study.

Estado limite de serviço de deformações horizontais excessivas com a consideração das alvenarias de preenchimento no modelo estrutural

Resumo Brazilian Codes NBR 6118 and NBR 15575 provide practical values for interstory drift limits applied to conventional modeling in order to prevent negative effects in masonry infill walls caused by excessive lateral deformability, however these codes do not account for infill walls in the structural model. The inclusion of infill walls in the proposed model allows for a quantitative evaluation of structural stresses in these walls and an assessment of cracking in these elements (sliding shear diagonal tension and diagonal compression cracking). This paper presents the results of simulations of single-story one-bay infilled R/C frames. The main objective is to show how to check the serviceability limit states under lateral loads when the infill walls are included in the modeling. The results of numerical simulations allowed for an evalu ation of stresses and the probable cracking pattern in infill walls. The results also allowed an identification of some advantages and limitations of the NBR 6118 practical procedure based on interstory drift limits.

Análise numérica e experimental da evolução de flechas de vigas de concreto armado sob ações cíclicas repetidas

This paper discusses the structural behavior of reinforced concrete beams subjected to cyclic loadings by numerical and experimental analysis. The main objective was to quantify the increase in deflections of the beams when subjected to repeated loading cycles. Experimental tests with the application of cyclic and monotonic loading were carried out with reduced size beams. The numerical analysis utilized a simplified damage model that is part of the group denominated lumped dissipation models. This model takes into account the damage increase as a function of the increase in the number of cycles, enabling an evaluation of the stiffness loss due to repeated loads. The experimental results not only confirmed the effect of repeated loads on the stiffness loss of beams, but also demonstrated the important influence of the flexural reinforcement ratio on cyclic behavior. Comparisons between the experimental results and those obtained with the numerical model provided support for the potential of the damage model employed in the prediction of the increase of deflections caused by repeated cyclic loading.