Floor slabs of deep basement structures are subjected to large compressive forces due to soil and hydraulic lateral pressures. In this study, nonlinear finite-element analyses were carried out to improve the existing moment magnifier method so that it is applicable to the long-term behavior of the flat plates. For this purpose, a computer program that can address creep and shrinkage as well as geometrical and material nonlinearity was developed. Parametric studies were performed to investigate the characteristics of the long-term behavior and the load-carrying capacities of flat plates. In the proposed moment magnifier method, the creep factor was introduced to accommodate the effect of creep on the load-carrying capacity. A design example was presented to demonstrate the proposed design method.
During construction of building structures, construction load significantly greater than the self-weight of a slab, is imposed on the early-age concrete slabs. As a result, according to the construction scheme, the construction load may causes excessive long term deflection and flexural cracking in a flat plate. However, the requirement of minimum thickness of the flat plate provided by the current design codes does not address such effect of the construction load on the slab. In the present study, a simplified design method was developed to calculate the deflection of a flat plate affected by the construction load and scheme. In the proposed method, a variety of design parameters affecting the long-term deflection of the plate was considered. Based on the proposed method, a design equation for estimating the minimum thickness of the flat plate was developed to be conveniently used in design work.
We report enhancement of the mechanical stability of graphene through a one-step method to disperse gold nanoparticles on the pristine graphene without any added agent.