Shear Flexural Strength Research Articles

One‐way flexural shear tests on wide reinforced concrete slab segments with simple and intermediate supports

One‐way flexural shear tests on wide reinforced concrete slab segments with simple and intermediate supports

Enhancement of the Shear-flexural Strength of the Rubberized Concrete Prism Beam by External Reinforcement

It has become necessary to use damaged tires from various vehicles to produce rubberized concrete structures as a good solution to treat environmental pollution and reduce the total cost of construction. In general, concrete structures, for many reasons, may need to be strengthened. Recently, fiber-reinforced polymer (FRP) sheets have been used to reinforce existing concrete structural elements that were deficient. FRP is an effective solution and is moderately common for strengthening and improving the properties of the structural element. Firstly, concrete mixes were poured with replaced sand, with the percentages varying from 0, 10, 20, and 30%. Thus, some mechanical properties in terms of the workability of concrete, compressive strength, tensile strength, and density of recycled concrete were studied using rubber from tires as an alternative to fine aggregate. Secondly, concrete prisms were poured with different proportions of rubber instead of sand. Twelve rubberized concrete prisms measure 100 mm x 100 mm x 600 mm. Then, the effect of fiber reinforced polymer with different forms on concrete prisms was investigated. The results revealed a decrease in the workability, density, and compressive strength of the rubber concrete samples with an increase in the proportions of replaced sand with rubber content. It is also observed that FRP improves the strength, stiffness, and ductility of all concrete prism beams with a different ratio of recycled rubber. In addition, the test results clearly show that the strengthening by width sheets of FPR behaved more favorably than the thin sheets having the same cross-section.

Experimental Study on Concrete-Filled Double Skin Circular Steel Tubular Beams under Bending Load

This paper examines the structural and mechanical behavior characteristics of the concrete-filled double circular steel tube (CFDT) fabricated with the installation of shape memory alloys (SMAs) and reinforcement bars in the inner and outer steel tubes, the inner-outer diameter ratio (Di/Do), and the concrete strength as the main variables. Towards this end, the displacement ductility, crack patterns, load-central deflection relationship, displacement ductility, and flexural shear strength were compared and analyzed. The results verified that a change in the Di/Do has significant effects on the crack pattern, maximum load, and ductility. The specimens with SMAs installed between the inner and outer steel tubes generally showed good results.

Direct and Flexural Shear Strength of Composite Beam with Perforbond Rib

When Perfobond Rib shear connectors are used as flexural materials in structures such as bridges, they show flexural shear behavior due to external force, rather than direct shear behavior. The aim of this study is thus to analyze the difference between both behaviors. First, we prepared a specimen to analyze direct shear behavior using Perfobond Rib shear connectors, analyzed the characteristics of behavior with a push-out test and proposed a formula of shear resistance assessment. Proposed formula shows a relatively good fit with less than 10% error. A flexural shear test was then conducted based on the result of the direct shear test. Based on the static flexural test it analyzed the flexural behavior and the flexural shear stress it calculated. Direct shear stress and EN 1994-1-1 to lead and be calculated, it compared the flexural shear stress and it analyzed in about the shear resistance stress which it follows in load direction. Finally, we compared both test results, and the comparison showed that the flexural shear stress is approximately 6% stronger than the direct shear stress.

Shear Design and Assessment of Reinforced and Prestressed Concrete Beams Based on a Mechanical Model

Safe and economical design and assessment of reinforced (RC) and prestressed concrete (PC) beams requires the availability of accurate but simple formulations which adequately capture the structural response. In this paper, a mechanical model for the prediction of the shear-flexural strength of PC and RC members with rectangular, I, or T sections, with and without shear reinforcement, is presented. The model is based on the principles of concrete mechanics and on assumptions supported by the observed experimental behavior and by the results of refined numerical models. Compact, simple, and accurate expressions are derived for design and verification of the shear strength, which incorporate the most relevant shear transfer actions. Excellent agreement between the predictions of the model and the results of the recently published ACI-DAfStb databases, including more than 1,287 tests on RC and PC beams with and without stirrups, has been observed. The theory behind the model provides consistent explanations for many aspects related to the shear response that are not clearly explained by current code formulations, making it a very helpful tool for daily engineering practice.

Shear capacity of concrete-filled steel plate composite coupling beams

The concrete-filled steel plate (CFSP) composite coupling beam is a newly developed form of coupling beam that possesses high deformation and energy dissipation capacities. In this paper, the shear capacity of concrete-filled steel plate composite coupling beams was investigated. An analytical model was proposed based on the force mechanism of the composite coupling beam and was proved to have adequate accuracy compared with the available test results. The shear capacity of the composite coupling beam was found to be governed by flexural strength, shear strength, or flexural-shear strength, depending on the material and geometrical properties of the coupling beam. By incorporating the effect of flexural-shear interaction, a unified equation was finally developed.

Predicting the shear–flexural strength of slender reinforced concrete T and I shaped beams

A mechanical model previously developed by the authors for the prediction of the shear–flexural strength of slender reinforced concrete beams with rectangular cross-section with or without stirrups has been extended to beams with T and I cross-sections. The effects of the section shape on each shear transfer action have been identified and incorporated into the corresponding equations. General expressions for strength verification and transverse reinforcement design have been derived. The contribution of the flanges to the shear strength is accounted for by means of an effective shear width, which depends on the section geometry and on the longitudinal reinforcement ratio. The effect of the vertical confinement stresses introduced by the shear reinforcement on the concrete web is also considered. The expressions derived are valid, as particular cases, for beams with inverted T or rectangular cross sections. The proposed equations have been checked with experimental results available in the literature, obtaining very good results. The simplicity, straightforwardness of application and the accuracy of the method make it suitable for daily engineering practice.

Shear-flexural strength mechanical model for the design and assessment of reinforced concrete beams subjected to point or distributed loads

A mechanical model recently developed for the shear strength of slender reinforced concrete beams with and without shear reinforcement is presented and extended to elements with uniformly distributed loads, specially focusing on practical design and assessment in this paper. The shear strength is considered to be the sum of the shear transferred by the concrete compression chord, along the crack, due to residual tensile and frictional stresses, by the stirrups and, if they exist, by the longitudinal reinforcement. Based on the principles of structural mechanics simple expressions have been derived separately for each shear transfer action and for their interaction at ultimate limit state. The predictions of the model have been compared to those obtained by using the EC2, MC2010 and ACI 318-08 provisions and they fit very well the available experimental results from the recently published ACI-DAfStb databases of shear tests on slender reinforced concrete beams with and without stirrups. Finally, a detailed application example has been presented, obtaining each contributing component to the shear strength and the assumed shape and position of the critical crack.

Shear-flexural strength mechanical model for the design and assessment of reinforced concrete beams

A conceptual model for the prediction of the shear-flexural strength of slender reinforced concrete beams with and without transverse reinforcement is presented. The model incorporates the shear transferred by the un-cracked concrete chord, along the crack's length, by the stirrups, if they are, and, in that case by the longitudinal reinforcement. After the development of the first branch of the critical shear crack, failure is considered to occur when the stresses at any point of the concrete compression chord reach the assumed biaxial stress failure envelope. A physical explanation is provided for the evolution of the shear transfer mechanisms, and the contribution of each one at ultimate limit state is formulated accordingly. Simple equations are derived for shear strength verification and for designing transverse reinforcement. The method is validated by comparing its predictions with the results of 1131 shear tests, obtaining very good results in terms of mean value and coefficient of variation. Because of its accuracy, simplicity and theoretical consistency, the proposed method is considered to be very useful for the practical design and assessment of concrete structures subjected to combined shear and bending.

Un modelo unificado de resistencia a flexión y cortante de vigas esbeltas de hormigón armado bajo cargas puntuales y repartidas

A mechanical model is presented for shear-flexural strength of slender reinforced concrete beams under concentrated or distributed loads. The model incorporates the shear transferred by the un-cracked concrete head, by the cracked web and by the longitudinal and transverse reinforcements. Failure is assumed to occur at the un-cracked concrete zone, subjected to a biaxial stress state, when the Kupfer failure envelope is reached and the stirrups are yielded. A general procedure and simplified direct design equations are derived taking into account equilibrium and a given stress distribution at ultimate limit states (ULS). The model predictions have been compared with the results of more than 1300 tests performed on simply supported beams, having obtained very good agreement. Because of the simplicity, accuracy, and the physical insight of the problem provided by the model, it may be very useful for rational performance-based design of concrete structures in practice.

Shear Strength of Reinforced Concrete Walls Subjected to Cyclic Loading

This research proposes a new shear strength model, based on modifications to the UCSD shear model by Kowalsky and Priestley [2000], to calculate the shear capacity and predict the displacement ductility of reinforced concrete walls in diagonal tension. An experimental database is created from a literature review of experimental tests of reinforced concrete walls that exhibit strength degradation and shear failure during cyclic loading. This experimental database is used in the formulation of the proposed shear model and to test the accuracy of the model. The proposed model improves the accuracy of calculating pre-emptive shear and flexure-shear strength, correctly identifies the failure mode for all collected specimens, and provides the closest prediction of the ultimate displacement ductility. Based on this research, the proposed shear model is recommended for the calculation of the shear strength of reinforced concrete walls for either the assessment of existing buildings or the design of new structures.

Strength and durability of hot-press glued-laminated timber beams

Hot-press glued-laminated timber was manufactured exclusively by one Canadian laminator between 1967 and 1970. Members made by this process have been found to be capable of seriously delaminating in service. The purpose of this study was to determine the strength and durability of lightly-delaminated hot-press beams. Eight such beams, plus two conventionally manufactured Glulam beams, provided material which was tested in either flexural-shear, flexural-tension-perpendicular-to-glueline after accelerated ageing, or vacuum-pressure cycling. For the accelerated ageing tests, material was subjected to either zero, one, two, four, six, or eight cycles of alternating high (85%) and low (35%) relative humidity at 50 °C, corresponding to equilibrium moisture contents of 16 and 6%, respectively. Flexural-shear strength of the hot-press material was somewhat lower than that expected of conventional material. Vacuum-pressure cycling of hot-press specimens resulted in delamination values exceeding the permissible amount. The average flexural-tensile strength of conventional material was substantially higher and less variable than that of hot-press material, both before and after accelerated ageing. Moreover, the flexural-tension-perpendicular-to-glueline tests after accelerated ageing cycles resulted in increased amounts of gluebond failure in the hot-press material. The results of the accelerated ageing and vacuum-pressure cycling tests indicate that even lightly-delaminated hot-press material has an inherent ability to delaminate and may perform poorly in situations of cyclic moisture environments.

CALCULATION OF FLEXURE-SHEAR STRENGTH OF PRESTRESSED CONCRETE BEAMS

FLEXURE-SHEAR STRENGTH CALCULATIONS OF SINGLE-SPAN AND CONTINUOUS PRESTRESSED CONCRETE BEAMS ARE DERIVED MAINLY FROM PROPERTIES OF THE COMPRESSION ZONE OF THE BEAM AND DEFORMATION AND EQUILIBRIUM CONDITIONS. SHEAR CARRIED BY THE COMPRESSION ZONE ESTABLISHES THE EFFECTIVE MOMENT-SHEAR RATIO AT A SECTION. MOMENT REDISTRIBUTION AT FAILURE IS BASED ON THE ULTIMATE STRENGTH OF CRITICAL SECTIONS. THE EQUATIONS DEVELOPED SHOW GOOD AGREEMENT WITH OBSERVED VALUES OF DIFFERENT INVESTIGATORS. /RRL/A/