Ll. Torres

A numerical model for sequential construction, repairing and strengthening of 2-D concrete frames

This paper presents a computationally efficient and accurate layer model for simulating, under serviceability conditions, the instantaneous and time-dependent static non-linear behaviour of 2-D reinforced and prestressed concrete building frames. Several types of situations can be considered: segmental construction, changes of material and cross-sectional properties, modifications in the joint and support conditions (including new shores) and addition or removal of new members and of external reinforcements. The proposed algorithm simulates damage, structural retrofit and construction or demolition. Cracking is described by a smeared model in which the tension-stiffening effect is considered in detail. The structural behaviour is described by a generalized matrix formulation where no initial assumption on the deformation shape is considered (since no shape functions are used). This formulation is accurate while computationally efficient for structures with many members (which generate models with a large number of degrees of freedom in standard finite element discretizations). The algorithm is validated by comparison with ad-hoc experiments and benchmark tests. Some applications are presented and relevant conclusions are derived from there.

Comparative Study of Deflection Equations for FRP RC Beams

The mechanical and bond characteristics of Fibre Reinforced Polymers (FRP) used as internal reinforcement for Reinforced Concrete (RC) elements result in larger deflections and crack widths compared to the conventional steel RC elements. Consequently, serviceability requirements may govern the design of such members. In the last 20 years, several approaches and codes of practice have been published to predict the theoretical deflection of FRP RC elements.

Experimental Study on the Tension Stiffening Effect of GFRP RC Elements

Direct tension test experiments are accepted to be adequate to study the tension stiffening effect of fibre reinforced polymer reinforced concrete (FRP RC) members. In this paper, an experimental program on direct tension tests on GFRP RC is presented. Four different reinforcing ratios were considered; the ties were instrumented to analyze the member behaviour (load-strain relationship and crack width). Measured member deformation and crack widths are compared with those calculated using the procedures of available codes for steel reinforced concrete, like EC-2 and ACI 224, as well as with ACI 440 for FRP reinforced concrete structures.