On the Residual Static and Impact Capacity of Shear-Reinforced Concrete Beams Subjected to an Initial Impact

Abstract

Impact loads in previous research showed to induce brittle responses of statically flexure-critical reinforced concrete (RC) beams designed for ductility. The impact load may produce flexural shear damage modes similar to that observed during quasi-static loads and local shear damage under the impact zone. The occurrence of shear damage modes during impact tests has been investigated extensively, but their effect on the residual quasi-static and dynamic capacity is not fully understood. For this aim, an initial high-velocity impact test initiated severe shear damage to RC beams. The beams were then tested quasi-statically and by sequential impact testing using the same setup as the initial tests. The results indicate a flexure-dominated response during sequential impact tests for beams containing extreme shear reinforcement amounts, favouring the energy-absorption capacity. Significant shear and flexural damage occurred for beams with less shear reinforcement, indicating a hybrid response that varied throughout the tests. The tests for the residual quasi-static capacity indicated severe consequences from initial local shear damage on the capacity, as shown by the brittle response of the beam with the most shear reinforcement. However, wide initial flexural cracks instead showed a favourable effect, as there was an indication of transfer from brittle to ductile failure. For beams showing both global and local shear damage, it was concluded that global shear damage modes were critical for the residual static and dynamic shear capacity.

Transient Responses of Repeated Transverse Impacts on Beams

“…As the predictions of impact response are significantly different by using different contact models, ten local contact models including elastic Hertz contact model [1] and 9 elastic-plastic contact models are used to analyze the local impact behavior of a sphere impacting on a beam repeatedly in this section. The ten local contact models are Hertz model [1], Thornton model [38], UC model [39], Stronge model [40], KE model [41,42], KK model [43], CYM model [9], MYC model [44], MJG model [27] and ML model [45].…”

“…Impacts on structures may result from, e.g., vehicle collisions, falling objects, or projectiles, which involve local impact behaviors, wave propagations and structural responses [1,2]. Although there are extensive researches on impact dynamics, the selection of an appropriate model/method for a given impact problem is still an important issue to be addressed [3].…”

“…The studies reveal the importance of wave propagations for impacts on slender bodies. Modal method by series expansions using modal functions has been applied to the beam impact problem, which was detailed by Goldsmith [1] and Eringen [17]. However, the evaluation of the strain in the beam is complicated due to the slow convergence of the series in the modal functions [1,18].…”

“…Modal method by series expansions using modal functions has been applied to the beam impact problem, which was detailed by Goldsmith [1] and Eringen [17]. However, the evaluation of the strain in the beam is complicated due to the slow convergence of the series in the modal functions [1,18]. As mentioned by Yin et al [19,20], the simplified equation proposed by Eringen [20] makes the dynamic solution dissatisfy the nonhomogeneous boundary conditions.…”

“…The nonlinear local contact behavior between the projectile and the structure is based on the contact model in the form of contact force-indentation relationship [7]. The well-known Hertz contact model [1] is a frequently used elastic contact model [5,21]. For impacts related to local inelastic problems, some elastic-plastic contact models [22][23][24][25][26][27][28]) have been proposed to account for energy loss due to local plastic deformations.…”