Shear Strength Of Members Research Articles

Toward a codified design of recycled aggregate concrete structures: Background for the new fib Model Code 2020 and Eurocode 2

AbstractThe use of recycled aggregate (RA) to produce recycled aggregate concrete (RAC) is a proven way of decreasing the consumption of natural aggregate (NA) and the landfilling of construction and demolition waste. However, adoption of codes for the design of RAC and RAC structures has been lacking. Within the framework of the new fib Model Code 2020 and Eurocode 2, provisions for RAC can be adopted. Therefore, in this study, a comprehensive and critical review of literature on RAC is performed as well as own meta‐analyses of results. Material properties of RAC and structural behavior of reinforced and prestressed RAC members are analyzed, and based on the findings, code adjustments for RAC are proposed. The results show that, in order to incorporate RAC into design codes, changes are necessary in expressions for physical–mechanical properties (volumetric mass, modulus of elasticity, tensile strength, fracture energy, peak and ultimate strains, shrinkage strain and creep coefficient), durability‐related properties (minimum concrete cover for durability) and structural behavior (shear strength of members not requiring shear reinforcement and deflections). The recommendations are formulated in terms of the total mass substitution ratio of RA that can be classified as Type A according to standard EN 206 for concrete. The results and findings presented herein can provide an important contribution toward the codification of RAC use and the wider utilization of RA in construction.

Shear Strength of Members without Transverse Reinforcement Based on Development of Critical Shear Crack

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Shear strength of hollow circular sections

ABSTRACT The number of buildings higher than 30 floors has shown remarkable growth; many of them are supported on foundations of hollow circular piles. This increasing of height of constructions causes an increment of the shear stresses that are transmitted to their foundations, however these elements are more shear critical due to the hollow core. Most of the existing codes are based on shear models for rectangular sections, and guidelines for assessment of shear strength of members with hollow circular cross sections are practically non-existent. This study evaluates, on a comparative basis, the shear strength of elements with hollow circular cross sections, obtained from experimental tests, with values computed using the Canadian Code (CSA A23.3) and using a proposed simple procedure based on the Brazilian standard (NBR 6118).

SEISMIC PERFORMANCE EVALUATION OF LOW STRENGTH CONCRETE MEMBERS WITH PLAIN ROUND BAR

In the series of experimental studies concerning low strength concrete members, it was pointed out that the flexural and shear strength of members with plain round bars was lower than the calculated values. This result is due to the occurrence of bond slip failure before yielding or shear cracking. A calculation flow to obtain the strength of the RC member with low strength concrete and plain round bar is proposed. This flow is verified with data of the previous studies.

Shear Strength of Reinforced Concrete Members Subjected to Monotonic Loads

A model to calculate the shear strength of reinforced concrete members subjected to monolonic loading was developed. The proposed model includes the contribution of the most significant mechanisms of shear transfer in reinforced concrete members identified in the research literature. The shear strength is calculated by the superposition of components related to arch action, truss action, friction, and the contribution of the uncracked compression zone. A procedure to calculate the shear strength of members in the transition phase from deep to slender members is formulated, so that the proposed expression can be used for members with geometric configurations varying from squat to slender members. The proposed model was found to provide good estimates of strength for members with and without transverse reinforcement, and having a wide range of geometric configurations and concrete compressive strengths.

Shear strength of members without transverse reinforcement

The variable angle truss model is extended to members without transverse reinforcement by introducing concrete tension ties perpendicular to concrete compression struts. The modified compression field theory approach of limiting the shear transfer across diagonal cracks is combined with the variable angle truss model to develop equations for the shear capacity of members without transverse reinforcement. These equations are the theoretical basis of tabulated values for members without stirrups in the general shear design method of the 1994 Canadian concrete code. This paper also presents the results from an experimental study in which 27 narrow (beam-like) wall elements, with significant longitudinal reinforcement and little or no transverse reinforcement, were subjected to combined axial tension, bending moment, and shear. The experimental results are compared with predictions from the 1994 Canadian concrete code, as well as the American Concrete Institute building code. Key words: building codes, reinforced concrete, shear strength, structural design, tension, tests, truss model.