3D nonlinear mixed finite-element analysis of RC beams and plates with and without FRP reinforcement

Abstract

Three 3D nonlinear finite-element (FE) models are developed to study the behavior of concrete beams and plates with and without externally reinforcement of fibre reinforced polymer (FRP). Ramtekkar's mixed layer-wise 3 dimensional (3D) 18-node FE model (108 degrees-of-freedom, DOFs) is modified to accommodate the nonlinear concrete and elasto-plastic steel behaviour. Saenz's stress-strain equation is used for material nonlinearity of concrete. As in any 3D mixed FE analysis, the run time using the model can be computationally expensive. Two additional layer-wise 18-node FE models: Displacement FE model (54 DOF) and transitional FE model (81 DOF) are developed.The displacement FE model is based on purely displacement field, i.e. only displacement components are enforced throughout the thickness of the structures. The transitional FE model has six DOF (three displacement components in the coordinate axis direction and three transverse stress components -where z is the thickness direction) per node in the upper surface and only three DOF (three displacement components in the coordinate axis direction) per node in the bottom surface. The overall intention for developing the two additional element models is to investigate the result quality with the reduction of computational time by using elements with less DOF in less critical part of structure. In this study we limited our effort to investigate the quality of the results rather than efficiency of the models. The analysis of reinforced concrete (RC) beam strengthened with FRP and composite plate using these models are verified against the experimental results and the results from the commercial software, ANSYS respectively.Several parametric studies are done on composite RC beam and composite plate.iii

Finite Element Simulation of Space Trusses

“…Increasing displacement to reach 6.39 mm, members (19)(20) and (19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30) were buckled and followed by buckling members (25-36) and (25-26) at displacement 15.67 mm. Also members (3)(4) and (23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34) collapsed in tension at displacement 33.52 mm (see Fig. 8).…”

“…With further increments of displacement, the members started to collapse in a symmetrical sequence about axis A-A as follow: the members (19)(20) and (19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30) failed in compression then the member (3)(4) in tension then the members (25-36) and (25-26) in compression. After that member (23-29) yielded then the members (31-32) and (31-42) buckled and followed by the buckling of members (20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31), (20)(21), and (42-43) (see Fig. 8).…”

Advances of Finite Element Analysis for FRP Concrete Beams

“…In the 1-D models, both the concrete and rebar and FRP sheet is modelled by a unified 1-D element (Faella et al 2008). In the 2-D and 3-D models (Hoque et al 2007), the rebar is usually modelled by one dimensional bar elements or truss element, the concrete is modeled by 2-D plane elements or 3-D solid elements, and the FRP sheet is usually modelled as plane element or shell element. To model debonding behavior, the interface between FRP and concrete is usually modelled using nonlinear spring elements.…”

Shear strengthening of reinforced concrete beams by means of vertical prestressed reinforcement

“…Concerning to the numerical modelling, RC shear-strengthened members have not been extensively studied, and the existing nonlinear FE models are mainly focused on simulations involving FRP strengthening techniques and 2D/3D nonlinear FE models; some examples are (Hoque, Rattanawangcharoen and Shah 2007;Kim and Vecchio 2008;Lee, Ha and Afzal 2008). These methods are usually very complex, time consuming and demanding, requiring fine FE meshes and large numbers of parameters (some of difficult definition), that can hardly be applied in practice.…”