Desempenho dos modelos da nbr-6118 para anÃlise de vigas contÃnuas em concreto armado

AUTOR(ES)

Gustavo de Moraes RÃgo

DATA DE PUBLICAÇÃO

2005

RESUMO

Continuous beams are essential to structural solutions to buildings, bridges and walkways. Collapse in flexure does not necessarily occur when critical section reaches its strength capacity. Due moment redistribution collapse may occur when a sufficient number of plastic hinges transforms the structure into a mechanism. On the other hand, in order to develop this mechanism it is required that certain critical sections have sufficient plastic hinge rotation capacity. The objectives of present work is to assess, compare with experimental results and implement the various structural analysis models included in NBR-6118: (I) Linearly elastic analysis; (II) Linearly elastic analysis with redistribution; (III) Plastic analysis; (IV) Nonlinear analysis. The second model uses redistribution factors allowed by the code. For plastic analysis a nonlinear optimization procedure is used the limits required plastic rotation in critical sections to allowable code values. In the computation of required rotations it may be used a bilinear or trilinear moment/curvature relationship. For the nonlinear analysis it is initially developed a computational procedure to compute moment/curvature relationship taking into account nonlinear constitutive relationships for steel and concrete, and for the former, among a number of curves a model is used that describes post pick compression behavior taking into account important factors like member size and deformation gradient. Tension stiffening is taken into account with a crack check procedure. With moment/curvature relationship defined nonlinear analysis of continuous beams is performed employing a deformation control secant stiffness algorithm. Finally, response (redistribution factors, mode of failure, ultimate load and moments at critical sections) of the presented models is compared to two-span continuous beams experiments available in the literature

ASSUNTO(S)

ductilidade anÃlise plÃstica anÃlise nÃo-linear engenharia civil concreto armado

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