Numerical analysis on shear resistance of ultra‐high performance concrete‐normal strength concrete composite beam

Abstract

Ultra-high performance concrete-normal strength concrete (UHPC-NC) composite beam is a brand-new composite structure. UHPC-NC composite beam not only has the interfacial problem of the two materials, but its shear resistance should be investigated, which directly determines the mechanical performance and engineering value. In this article, the finite element analysis (FEA) method combined with the UHPC-NC composite beam shear experiment are used to analyze the shear resistance of the composite beam and the influence of the interfacial zone on the shear behavior. The shear span-to-depth ratio, UHPC layer, and longitudinal reinforcement of specimens are designed to study the shear mechanism. Then the FEA model is used to simulate the cooperative working properties of the concrete beam and the UHPC layer, which includes two conditions-slip and no-slip. The shear resistance, load-span deflection curve and the strain of longitudinal reinforcement of the UHPC-NC composite beams are analyzed and studied in combination with the results of shear experiment. The results show that the UHPC-NC composite beam can effectively improve the ultimate shear resistance and ductility of the beam. At the same time, the interfacial zone of UHPC-NC composite beam at the ultimate stage is a weak area, the cracking of that will has adverse effects on the mechanical properties of the composite beam, which needs to be paid attention to in the structural design. K E Y W O R D S composite beam, finite element analysis, interfacial zone, ultra-high performance concrete 1 | INTRODUCTION Ultra-high performance concrete (UHPC) is a new type of ultra-high performance cement-based composite material, which is defined that it has pre-and post-cracking strength greater than 5 MPa and compressive strength beyond 150 MPa by MCS-EPFL document. 1The toughness and crack resistance of UHPC are improved with the addition of steel fibers. At the same time, due to the optimized grade of UHPC matrix, the corresponding water-cement ratio and porosity are greatly reduced, which ensure that UHPC has the excellent impermeability and durability compared with

Theoretical and Experimental Investigation on the Flexural Behaviour of Prestressed NC-UHPC Composite Beams

“…This caused the beam to undergo an early collapse compared with the others and to show no obvious yielding phase. During the failure stage, the appearance of numerous fine cracks in the interfacial zone and reduction in the interfacial zone stiffness may explain this, consistent with the conclusion of [ 18 ].…”

“…In recent years, a considerable amount of experimental research has been undertaken on the flexural behavior of NC-UHPC composite beams, including that reported in [ 14 , 15 , 16 , 17 , 18 ]. In [ 14 ], the bond strength between UHPC and NC was found to be very high.…”

“…Therefore, the concrete beam and the UHPC layer can be understood to operate closely together. However, at the ultimate stage, due to a large number of fine cracks in the interfacial zone, the concrete will be softened, and the stiffness of the interfacial zone will be reduced, which represents one of the main failure modes of the composite structure [ 18 ].…”

Study on interfacial performance of ordinary concrete composite structure strengthened by ultra-high performance concrete —A review

“…The research of UHPC hardening NC interface involves many aspects. At present, many scholars have done a lot of experimental and numerical researches on the mechanical properties and engineering application technology of UHPC hardening NC interface, including the constraint contraction force and interfacial adhesion force (Kadhim et al, 2021; Qi et al, 2021; Tong et al, 2021; Li et al, 2020a; He and Chao, 2021).…”

Structural reliability of ultra‐high‐performance fiber reinforced concrete beams in shear

“…To understand the fiber contribution to the shear capacity of UHPFRC beams, experimental [8][9][10] and numerical [11][12][13] studies compared the experimentally predicted shear capacity to the shear capacity prediction models in the current UHPFRC structural codes. Notable differences between experimental and current shear models in predicting shear capacity are indicated in these experimental and numerical studies.…”