Effects of Creep and Shrinkage on the Behavior of Reinforced Concrete Gable Roof Hyperbolic-Paraboloids

摘要

Time-dependent deformations due to creep and shrinkage modify the response of structures sensitive to small geometrical changes such as the hyperbolic-parabola. In the investigation, a general finite element program is extended to consider time dependent and time independent characteristics of concrete in shell-beam structures. Cracking, concrete compressive nonlinearity, steel nonlinearity, and concrete-steel interaction are considered in the time independent model, while aging, creep and shrinkage are included in the time dependent one. Among the parameters considered, the manner of constraint in the support, and the size and position of the crown beams are important. A decrease of 25-50% in the load carrying capacity level has been observed considering time dependent effects, displacements are increased four to eight times from the time dependent ones, and large stress redistributions have been found to occur with a shift in the load carrying mechanisms from membrane to flexural. Design considerations emerging from the numerical results are highlighted in an effort to improve the design criteria basis for this kind of structure.