Concrete Shear Research Articles

Shear behavior of fiber reinforced concrete beams with high fly ash content

The shear behavior of Fiber Reinforced Concrete (FRC) beams with high Fly Ash (FA) content is investigated experimentally. Despite greater understanding of FRC shear behavior for the design of structural elements such as beams, the practicality of FRC with a high FA content has yet to be determined. Despite the fact that substantial study has been undertaken to establish the optimal usage of FA as a cement and fine aggregate replacement in concrete while investigating the shear behavior of conventional concrete, only a few studies have focused on the influence of FA in the FRC on concrete's shear behavior. The findings of shear tests performed on the FRC concrete beams of dimension 900 mm long by 80 mm wide by 120 mm high containing a high FA content up to 50 % are presented in this study. This study's principal goal is to investigate the impact of factors such as FA replacement level with fine aggregate and fiber volume on the shear behavior of concrete beams. Concrete mix with different combinations of 50 % FA by weight, as a replacement for fine aggregate, and steel fiber 1 % by volume is investigated. A four-point loading setup was used to test each of the beams. The results on FRC shear resistance capacity at failure load, as well as the effect of fiber volume and high FA content on ultimate load, have been presented and discussed. Mid-span deflection and crack patterns are also investigated during testing. The test results reveal that FRC overperforms in the presence of FA at a level of 50 % fine aggregate replacement with FA. Fibers, as expected, delayed crack formation and significantly reduced their width. As a result, it can be concluded that 50 % fine aggregate replacement with FA can be used effectively in concrete construction with no significant loss in shear strength, both in the presence and absence of steel fibers.

A field study of the relationship between sound insulation and noise annoyance, activity disturbance and wellbeing in multi-unit residences

Impact and airborne noise are often an issue for occupants in multi-unit residential buildings (MURBs). Despite minimum sound insulation requirements in building codes, occupants still complain about the impact and airborne noise which suggests that there is a lack of understanding of the relationship between sound insulation and occupants’ perceptions of their acoustic environment. To enhance existing knowledge on the relationship between sound insulation and occupants’ perception of noise, a field investigation was carried out in five Canadian MURBs with heavy-weight floor construction and concrete shear and steel stud walls. Airborne and impact sound insulation were measured, and surveys were conducted to assess subjective annoyance levels and effects on occupants’ various daily activities. The study found a significant correlation between airborne sound insulation and annoyance. However, there was no significant relationship between impact sound insulation and annoyance. The results showed no significant difference in impact noise annoyance between occupants in a building with high impact insulation (AIIC 62) compared to occupants in buildings with low impact insulation levels (AIIC 31–32). However, a significant correlation was found between impact sound insulation and reported effects of noise on work performance at home suggesting that disturbance of work or other activities might be a better indicator of occupants’ perception and acoustic comfort compared to annoyance ratings. In addition, the analysis revealed that occupants in suites located at the most exposed façade facing a major roadway report lower annoyance levels. The results indicate that the masking effects of outdoor or other noise sources should be considered when investigating occupants’ perception of impact and airborne noise.

SHEAR TRANSFER BEHAVIOR OF FIBROUS CONCRETE

Fibrous concrete's shear strength behavior is important in structural design. Brackets, corbels, and ledger beams are examples of concrete members that might collapse in shear. Such a failure might be brittle and sudden. Fibers improve concrete's behavior by increasing residual shear transfer and reducing crack development and extension. In an experimental study, nine push-off specimens were divided into three groups and examined as part of the experiment. Conventional concrete, conventional concrete with 1% glass fiber, and conventional concrete with 1% steel fiber were the groups. There were three push-off specimens with various shear reinforcement ratios in each of the groups that were examined (0.0, 0.45, and 0.68%). The specimens utilized had dimensions of 500mm x 250mm x 125mm. The vertical slip and horizontal separation at the shear plane were measured using two-stroke linear variable displacement transducers (LVDT). The effect of fiber type and the ratio of transverse reinforcement across the shear plane were the parameters evaluated. The presence of fibers enhances final shear strength, which is more obvious in specimens without stirrups in the shear plane. Where the addition of 1% of glass fiber to normal strength concrete increased ultimate shear strength by 32.26%, 12.38%, and 12.5%, while adding 1% of steel fiber to normal strength concrete increased ultimate shear strength by up to 53.22%, 19%, and 25%, respectively, for the specimens without stirrups, two stirrups, and three stirrups. The fibrous specimens were stiffer and ductile failure was seen. Steel fibers improved overall concrete shear behavior better than glass fibers.

Key Points for Construction Quality Control of Steel Bar Concrete Structure

In view of the good effect of steel bars in improving the elastic-plastic and flexural properties of concrete structures, combined with the good compressive strength of concrete, steel bars in the traditional reinforced concrete column and shear wall structures can greatly improve the performance of the main stress-bearing structures of super high-rise buildings. In order to clarify the key points of construction quality control of steel bar concrete structure, the control points are analyzed by theoretical analysis method combined with an engineering example. The results show that it is feasible to replace the traditional solid web section steel with the scattered steel bars to solve the difficult problem of the layout of the stirrups and longitudinal bars of the solid web section steel reinforced concrete column, and the ear plate connection of the steel bars is feasible; BIM Technology can realize the accurate positioning of steel bars and greatly improve the construction quality of steel bar concrete structures; During the construction process, it is very important to strictly control the verticality of steel bars, the spacing between steel bars, the spacing between steel bars, the distance from the outside of steel bars to the reinforcement at the column edge, and strictly control the quality of formwork installation and concrete pouring to ensure the quality of steel bar concrete structure.

Shear Resistance of Fibrous Reinforced Concrete Corbels - A Critical Review

Reinforced concrete corbels have become a frequent attribute in building construction, with precast high-strength concrete increasing use. Corbels are short-hunched cantilevers that project from the inner face of columns or walls to support heavy concentrated loads or beam reactions. They are essential structural elements for supporting precast beams, girders, cranes, and other precast structure systems. This paper reviews the effect of fiber, shear span to depth ratio, concrete strength, and reinforcement ratio on the reinforced fibrous high strength concrete corbel's shear resistance in previous research. The results show that the shear resistance of corbels enhances with increasing main reinforcement, compressive strength, and the volume fraction of fibers, whereas it decreases with the improvement of the shear span-to-effective depth ratio of the corbel. In addition, using fibers in high-strength reinforced concrete corbel increases the ductility and thus defines the mode of failure of the corbels, depending on the fiber parameters.

A Novel Shear Strengthening of Existing RC Shear Walls Using Steel Wire Mesh and Polymer Mortar

A new type of strengthening technique for existing reinforced concrete (RC) shear walls was proposed using steel wire mesh (SWM) and polymer mortar. The experimental campaign consists of testing one conventional RC shear wall specimen and four specimens strengthened using different configurations of steel wire mesh ratios and wrapping methods under cyclic lateral loading. The experimental results showed that the application of steel wire meshes and polymer mortar not only delayed the shear cracks formation but also effectively controlled the crack propagation. The average increase in cracking load of strengthened specimens was about 79%. The lateral load-carrying capacity of the strengthened specimens increased (about 55%) with the increase in the considered steel wire mesh reinforcement ratio compared to the control specimen. Wrapping of steel wire meshes around the shear wall surface prevented debonding of polymer mortar layers, and enhanced the performance compared to wrapping only on exposed surfaces. A theoretical expression to estimate the capacity of the strengthened shear walls was proposed based on the softened strut-and-tie model. The proposed expression fairly predicted the capacity of the strengthened specimens for the present and previous study.

Seismic Performance of Grille-Type Steel Plate Concrete Composite Walls with Application in a Super-High-Rise Building

The grille-type steel plate concrete composite wall (GSPCW) is an innovative shear wall system that mainly consists of steel faceplates, steel tie plates and infilled concrete. Compared to traditional steel plate concrete composite shear walls, the advantages of GSPCW walls include: (1) relatively high lateral and buckling resistance; and (2) simple structural measures for convenient construction and implementation. This paper presents the results of extensive numerical investigations regarding GSPCW systems, examining both GSPCW wall components and their application in a super-high-rise building as a case study. First, typical GSPCW wall models are established using DIANA software, and the numerical models are validated on the basis of comparison with results from previously reported experimental tests. The verified models are further used to perform parametric analyses with the aim of further understanding the effects of various design parameters on the seismic performance of GSPCW systems, including steel ratio, axial load ratio, height-to-width ratio, aspect ratio of the grille steel plate, and concrete compressive strength. Second, a super-high-rise building was selected for application to perform a case study of a GSPCW system. The seismic performance of the tall building in the case study was comparatively evaluated on the basis of both nonlinear time history analysis and modal pushover analysis (MPA), and the results from both of these methods validated the use of GSPCW is an efficient structural wall system appropriate for use in super-high-rise buildings. Finally, a simple economic assessment of the GSPCW building was performed, and the results were compared with those obtained for conventional reinforced concrete wall buildings.

On direct determination of shear force taken up by concrete in oblique cross-sections of reinforced concrete structures

A method has been presented for the direct determination of shear force in oblique cross-sections of reinforced concrete structures using a classic formula Q=bzτ, when the main problems of determining the shear force in oblique cross-sections are related to finding cleaving stresses in concrete and the shape of a stress-block of normal stresses in the design section, with no principles of practical division between the forms of failure in oblique sections due to concrete compression or shear. This work incorporates a criterion for dividing the forms of failure due to concrete compression or shear, based on the assumed shape of a compression stress-block with a segment cut away in a normal section, passing through the top of an inclined crack. The height of the compressed area in this normal section is defined from simultaneous solution of the equations of equilibrium in the moments in normal and oblique sections, from testing the experimental beams made of concrete and gas-concrete. This work deals with seeking the approaches for solving the above-mentioned problems in practice. The data of testing beams from gas-concrete and heavy-weight concrete have been used. Strain gauges were used to measure concrete and reinforcement deformities, computer processed thereafter. The studies have been considered on determination of cleaving stresses in oblique sections, further verified according to this method on certain alternative schemes of their application. A practical method for finding the shear force depending on the value of a shear span has been proposed. The work can encourage active discussion of this computation method.

Analisis Pengaruh Lokasi Dinding Geser Terhadap Pergeseran Lateral Bangunan Bertingkat Beton Bertulang 5 Lantai

Indonesia is one of the countries in the earthquake region. Therefore, it is necessary to build earthquake-resistant buildings to reduce the risk of material and life losses. Reinforced Concrete (RC) shear walls is one of effective structure element to resist earthquake forces. Applying RC shear wall can effectively reduce the displacement and story-drift of the structure. This research aims to study the effect of shear wall location in symmetric medium-rise building due to seismic loading. The symmetric medium rise-building is analyzed for earthquake force by considering two types of structural system. i.e. Frame system and Dual system. First model is open frame structural system and other three models are dual type structural system. The frame with shear walls at core and centrally placed at exterior frames showed significant reduction more than 80% lateral displacement at the top of structure.

Structural Performance and Reinforcement Improvement of Structural Walls Using Strain-Hardening Cementitious Composites

Reinforced concrete (RC) shear walls are effective in improving lateral stiffness and load-carrying capacity under earthquake and wind loads. According to the level of seismic design, however, the spacing of reinforcing steel bars should be very narrow and complicated, with tight spacing of tied bars, as is the case with seismically special RC shear wall design. The purpose of this study was to investigate the applicability of strain-hardening cementitious composites (SHCCs) in structural walls in order to improve structural performance as well as the complications with reinforcement details. The SHCC was mixed, and mechanical tests showed that the SHCC exhibited high ductile tensile strains above 2.0%, while sustaining the tensile stress after cracks and developing multiple microcracks, avoiding crack localizations. Six specimens of RC and reinforced SHCC structural walls were designed and manufactured with varying reinforcement details, and experiments on wall specimens were carried out under transverse wall-loading tests. These experiments demonstrated that the use of SHCC in structural walls, despite minimum use of reinforcement ratios, showed improved responses to minimize damage and failure caused by localized cracks under bending and shear to compared with the use of normal reinforcement ratios in RC walls.

Punching Shear Strength of Reinforced Concrete Flat Plates with GFRP Vertical Grids

In this study, the structural behavior of reinforced concrete flat plates shear reinforced with vertical grids made of a glass fiber reinforced polymer (GFRP) was experimentally evaluated. To examine the shear strength, experiments were performed on nine concrete slabs with different amounts and spacings of shear reinforcement. The test results indicated that the shear strength increased as the amount of shear reinforcement increased and as the spacing of the shear reinforcement decreased. The GFRP shear reinforcement changed the cracks and failure mode of the specimens from a brittle punching to flexure one. In addition, the experimental results are compared with a shear strength equation provided by different concrete design codes. This comparison demonstrates that all of the equations underestimate the shear strength of reinforced concrete flat plates shear reinforced with GFRP vertical grids. The shear strength of the equation by BS 8110 is able to calculate the punching shear strength reasonably for a concrete flat plate shear reinforced with GFRP vertical grids.

Numerical Verification of Strut and Tie Models and Failure Modes of Reinforced Self-Compacting Concrete Deep Beams

This study utilized Finite Element Method (FEM) to analyse the structural behaviour and failure modes of Reinforced Self Compacting Concrete (RSCC) deep beams. Eighteen deep beam specimens subjected to four-point loadings were modelled and analyzed using Abaqus modelling tool. Damage plasticity model was used to characterised the nonlinear behaviour of concrete material while linear elastic, linear-plastic-hardening model represented the reinforcing steel material behaviour. The results of the finite model were compared with four different Strut and Tie Models (STMs) using one-way Analysis of Variance (ANOVA). Results of the numerical study revealed that the concrete strength and shear span to depth ratio mostly affect the load-deflection response of the beams. Also, the failure modes of the studied deep beams were influenced by shear span to depth ratio, concrete strength as well as web reinforcement distribution. The ANOVA results also showed that the FEM outperformed the existing STMs.

Seismic Performance of Existing RC Structural Walls Retrofitted in Flexure by Wall End Plate

A study was conducted for the flexural retrofit of an old apartment house composed of a reinforced concrete (RC) shear wall structure. For the shear wall, a vertical retrofit was performed to both ends of the wall targeting the slender wall to improve the flexural performance. The retrofit materials were steel plate, epoxy, and non-shrink grout, and they were connected to the existing shear wall using post-installed chemical anchors. The concrete at the wall ends was broken and retrofitted as much as necessary to maintain the shear wall’s length. The points to be noted are the fracture of the welded part of the flexural retrofit and the chemical anchor’s pulling. After the real scale specimen was fabricated by simulating the existing shear wall, the retrofit effect was experimentally verified by breaking the wall ends, retrofitting the ends, and applying repeated cyclic lateral loads. A total of three specimens were fabricated and retrofitted using steel plates and steel tubes. Since this experiment evaluated the flexural performance, the experiment was performed with a cantilever setting. The flexural retrofit effect using steel was analyzed through the load–displacement relationship, stiffness degradation, and energy dissipation, and through this, the bond of the retrofit and the behavior of the wall were verified.

An Experimental Study on the Basic Mechanical Properties and Compression Size Effect of Rubber Concrete with Different Substitution Rates

An experimental study was carried out on the uniaxial compression, uniaxial splitting, pure shear, and compression size effect of rubber concrete with 5 different substitution rates by applying hydraulic servo and direct shear apparatus. Then, by comparing the failure modes and ultimate strength eigenvalues of rubber concrete under different loading conditions, the following conclusions were drawn: with the increase of rubber substitution rate, the concrete specimens maintain a relatively good integrity under uniaxial compressive failure; on the contrary, the failure sections under uniaxial slitting and pure shear gradually become uneven with an increasing amount of fallen rubber particles. With the increase of specimen size, the integrity of rubber concrete after failure is gradually improved. Affected by an increased rubber substitution rate, the uniaxial compressive strength, splitting tensile strength, and shear strength of the concrete gradually decrease, while the plastic deformation capacity gradually increases. Specifically, the compressive strength is reduced by a maximum of 60.67%; the shear strength is reduced by a maximum of 49.85%; and the uniaxial splitting strength is reduced by a maximum of 58.38%. Then, we analyzed the strength relationship and the underlying mechanism among the three types of loading modes. It is found that, at the same rubber substitution rate, the compressive strength of rubber concrete gradually increases as the specimen size decreases, and the size effect on the compressive strength gradually decreases as the rubber substitution rate increases. Meanwhile, we performed qualitative and quantitative analysis on the equation describing the coupling effect of specimen size and rubber substitution rate on the compressive strength; the results suggest that the proposed equation is of a high level of applicability. Our research has a reference value for the application and promotion of rubber concrete in actual engineering projects.

Behavior of composite CFST beam-concrete column joints

This paper introduces a new composite joint, which is the composite CFST beam- concrete column joint, and it is more convenient for transportation and erection than conventionally welded joints. The main components of this joint include steel H-beams welded with CFST beams, reinforced concrete columns, and reinforced concrete slabs. The steel H-beams and CFST beams are connected with a concrete slab using shear connectors to ensure composite action between them. An experimental investigation was conducted to evaluate the proposed composite joint performance. A three-dimensional (3D) finite element (FE) model was developed and analyzed for this joint using the ABAQUS/explicit. The FE model accuracy was validated by comparing its results with the relevant test results. Additionally, the parameters that consisted of the steel box beam thickness, concrete compressive strength, steel yield strength, and reinforcement ratio in the concrete slab were considered to investigate their influence on the proposed joint performance.

Effect of shear span-to-depth ratio on posttensioned concrete crane beams shear capacity

The shear span-to-depth ratio has the most significant influence on the shear capacity of beams and determines their failure mode. The subject of the current project is the shear capacity of precast posttensioned concrete crane beams disassembled after more than fifty years of being used in an industrial plant. The paper gives the theoretical basis for the shear capacity of such elements as well as standard design models. The conducted tests showed that despite the low shear reinforcement ratio, the elements do not fail in a brittle mode but show a clear indication of prospective destruction. It was also confirmed that in the case of poorly shear-reinforced PC elements, a clear arch action can be distinguished with a low shear span-to-depth ratio, whereas in the case of a higher ratio there is a classical beam action.

Vector mechanics-based simulation of large deformation behavior in RC shear walls using planar four-node elements

For the large deformation of shear walls under vertical and horizontal loads, there are difficulties in obtaining accurate simulation results using the response analysis method, even with fine mesh elements. Furthermore, concrete material nonlinearity, stiffness degradation, concrete cracking and crushing, and steel bar damage may occur during the large deformation of reinforced concrete (RC) shear walls. Matrix operations that are involved in nonlinear analysis using the traditional finite-element method (FEM) may also result in flaws, and may thus lead to serious errors. To solve these problems, a planar four-node element was developed based on vector mechanics. Owing to particle-based formulation along the path element, the method does not require repeated constructions of a global stiffness matrix for the nonlinear behavior of the structure. The nonlinear concrete constitutive model and bilinear steel material model are integrated with the developed element, to ensure that large deformation and damage behavior can be addressed. For verification, simulation analyses were performed to obtain experimental results on an RC shear wall subjected to a monotonically increasing lateral load with a constant vertical load. To appropriately evaluate the parameters, investigations were conducted on the loading speed, meshing dimension, and the damping factor, because vector mechanics is based on the equation of motion. The static problem was then verified to obtain a stable solution by employing a balanced equation of motion. Using the parameters obtained, the simulated pushover response, including the bearing capacity, deformation ability, curvature development, and energy dissipation, were found to be in accordance with the experimental observation. This study demonstrated the potential of the developed planar element for simulating the entire process of large deformation and damage behavior in RC shear walls.

Shear Strength Equation of Concrete Wide Beam Shear Reinforced With Steel Plate Considering Transverse Spacing and Support Width

Shear Strength Equation of Concrete Wide Beam Shear Reinforced With Steel Plate Considering Transverse Spacing and Support Width

Concrete block structural masonry beam shear design: theoretical and experimental analysis and recommendations to the brazilian standards

Abstract Beams are subject a flexure and shear, with the last as the theme of this research. The purpose of this paper is to analyze specifications for the shear design of concrete block structural masonry beams, based on an extensive literature review and experimental tests here reported. From this scope, specifications for revision of Brazilian standardization are suggested. In the theoretical part, literature review from both national and international researchers were considered and the specifications of Brazilian standards, in addition to North American, Australian, Canadian and European, ABNT NBR 15961-1/2011, ABNT NBR 6118/2014TMS 402/2016, AS3700/2001, CSA S304/2014 and EuroCode6.1/2001, respectively. To analyze and validate the specifications of the literature, an experimental program was carried out assessing ten concrete block masonry beams results tested mainly to shear loads. Two-course high beams with three vertical load positions (position a/d) and two transverse reinforcement rates were tested. The specifications from the Brazilian and European standards led to considerably higher results than the experimental results, while those presented in the standards TMS 402/2016, AS3700/2001, CSA S304/2014 and NBR6118/2014 lead to results close to those obtained experimentally. As a conclusion, it can be noted that the rupture pattern is similar to that expected for reinforced concrete beams, the cracks were conditioned by the position of the loading point and by the mortar joints positions, the increase in the transverse reinforcement ratio led to an increase in the shear force. Results indicate that the consideration of apparent increase in shear strength by the ratio M ⁄ (V∙d) is not consistent. Eliminating this recommendation, considering the masonry shear strength equal to 0.35 MPa, limiting the stirrups tension to 0.90 of fyk and considering the contribution of the longitudinal reinforcement, it was possible to estimate the shear value at the rupture of each beam between 73% to 106% of the values verified in the tests.

Estimation of Tensile Strength of High Strength Concrete Based on Experimental Results

Use of high strength concrete require reliable predictions of correlations of compressive strength with tensile strength or splitting strength. Analysis of correlation between tensile strength of concrete and compressive strength, based on experimental results, is shown in this paper. It is proposed new simple correlation. Regression analysis that use, is based on the results of the experimental researches of compressive strength and splitting tensile strength, at specimens of high strength concrete. Comparative analysis of test results, gained for high strength concrete and normal strength concrete is performed. Analysis comprises the results of the experimental research of deep beams subjected to shear. Stresses measured on surfaces of high strength concrete beams subjected to shear and level of stresses that induce inclined cracks in concrete are applied. Relationship between concrete compressive strength and shear cracking stresses is studied, too. Experimental research was done at pairs of the beams made of concrete with high compressive strength and normal compressive strength. Estimation of validation of relations prescribed by the design codes for high strength concrete has performed.