Influence of Lap Splices on the Deformation Capacity of RC Walls. I: Database Assembly, Recent Experimental Data, and Findings for Model Development

Abstract

Recent postearthquake missions have shown that reinforced concrete (RC) wall buildings can experience critical damage owing to lap splices, which led to a recent surge in experimental tests of walls with such constructional details. Most of the 16 wall tests described in the literature thus far were carried out in the last six years. This paper presents a database with these wall tests, including the description of a new test on a wall with lap splices and a corresponding reference wall with continuous reinforcement. They complement the existing tests by investigating a spliced member with a shear span ratio smaller than two, which is the smallest among them. The objective of this database is to collect information not just on the force capacity but mainly on the deformation capacity of lap splices in reinforced concrete walls. It is shown that (1) well-confined lap splices relocate the plastic hinge above the lap splice, (2) lap splices with adequate lengths but insufficiently confined attain the peak force but their deformation capacity is significantly reduced, and (3) short and not well-confined lap splices fail before reaching the strength capacity. The analysis of the test results, which are used in the companion paper for the finite element analysis of walls with lap splices, indicates in particular that the confining reinforcement ratio and the ratio of shear span to lap splice length influence the lap splice strain capacity.

Influence of Lap Splices on the Deformation Capacity of RC Walls. II: Shell Element Simulation and Equivalent Uniaxial Model

“…Fig. 2 displays as an example the mesh discretization of the specimen TW3 tested by the authors (Almeida et al 2017). As noted, the displacement is applied at the wall cantilever height (i.e., at the shear span height) and does not necessarily correspond to the height of the displacement imposed in the experiment.…”

“…Following the discussion in the companion paper (Almeida et al 2017), monotonic splice strength is in this paper accepted as an estimate of the splice capacity under cyclic loading.…”

“…Finally, if splices are additionally well confined, not only the yield strength can be developed but also a degree of ductility is attainable (Gergely and White 1980;Lowes et al 2012). Because splices primarily rely on force transfer by steel-concrete bond, which is an intrinsically brittle deformation mechanism that can be quickly exhausted, such displacement ductility capacity will be always lower than the ductility capacity of a continuous rebar, particularly under the effect of cyclic loads (Almeida et al 2017). Nevertheless, for the assessment of existing structures such contribution to the inelastic deformation can be relevant and should not be neglected.…”

“…For the entire set of test units, the material properties, geometrical features, and reinforcing layout are presented in Table 1 and Fig. 1 of Almeida et al (2017).…”

“…The derived monotonic constitutive model, which intends to be an envelope of the cyclic response of lap splices up to the onset of strength degradation, is built from two defining points representing an equivalent yield and an ultimate condition. The yield point is related to the lap splice strength, for which the existing large number of literature proposals are first reviewed and subsequently applied to the spliced RC walls of the database collected in Table 1 of the companion paper (Almeida et al 2017), which includes 16 walls with lap splices plus eight reference units with continuous reinforcement. The ultimate strain capacity describes instead the point of strength degradation onset triggered by the presence of lap splices in the structural member and is obtained from regression analysis of the response of the 16 spliced units.…”