Shear Span Ratio Research Articles

Study on the effect of pre-stressed level on the force performance of wedge steel plate jacket and steel wire mesh-PCM strengthened RC beams

In this study, the shear behavior of reinforced concrete (RC) beams strengthened with wedge steel plate jacket (WSPJ) and high-strength steel wire mesh-polymer cement mortar (PCM) was investigated. The total contained 6 strengthened beams and 3 control beams, the test variables were the level of prestressing applied to the steel wire and the shear-span ratio of the RC beam. Our findings indicate that shear failure and bending failure were two types of strengthened beams failure, and the WSPJ and steel wire mesh-PCM strengthening technology can effectively improve the shear bearing capacity and ductility of RC beams. Furthermore, it delayed and inhibited the emergence and development of oblique cracks. Under the same shear-to-span ratio, the characteristic load as well as the shear bearing capacity of strengthened RC beams were significantly increased with the increase of prestressing level. The ductility is increased, and the damage mode of strengthened RC beams was changed. Finally, a modified model based on Truss-Arch model was proposed to forecast the shear capacity of strengthened beams. This model considers the impacts of the prestressing level and the shear-to-span ratio and then validated by the experimental data.

Performance and strength analysis of shear walls with vertical steel encased profiles under tensile-shear load

This study investigates the behavior of composite steel reinforced concrete (SRC) walls under tension-shear (TS) coupled stress state during earthquakes. Quasi-static tests on five SRC shear walls with a shear span ratio of 1.42 were conducted. The experimental results demonstrated that the SRC shear wall retained its high shear capacity and good ductility in shear failure mode. The stiffness analysis revealed that the concrete provided most axial stiffness before cracking but gradually withdrew from the work as the cracks developed and extended rapidly in the tension loading phase. And the effective lateral stiffness was approximately 10%–15% of the elastic lateral stiffness. Parametric analysis was conducted on the shear capacity, including the axial tensile ratio, steel profiles content, concrete strength grade, and horizontal distributed bar diameter. Additionally, the predictive formulas for the shear capacity in the codes of various countries were compared. It was found that the European and American code inadequately predict the shear capacity of specimens, and the Chinese code has higher safety. These findings can provide references for the practical engineering applications of SRC shear walls in earthquake-prone regions.

Experimental study and numerical simulation on shear behavior of steel and concrete composite beam with molybdenum tailing

To improve the flexural performance of steel–concrete composite beams and alleviate the problem of sand depletion caused by the application of concrete structures, this paper proposes a new type of steel-molybdenum tailings concrete composite beam. In order to further study the shear performance of the new type of steel-molybdenum tailings concrete composite beam, this paper couples molybdenum tailings replacement ratio (0%, 50%, and 100%) and shear span ratio (1 and 2) as research parameters, designs a total of six 1:2 scaled composite beam models, and conducts monotonic loading tests to study the failure process, failure mode, ultimate bearing capacity, deformation, and local strain of some typical measuring points of the new composite beam. The steel and concrete composite beam with the molybdenum tailing has the similar mechanical behavior for each ratio of the shear span to the effective depth with that of the steel and concrete composite beam. In addition, they have a little difference in the failure processes for each ratio of the shear span to the effective depth, whereas they show typical diagonal compression failure mode for the ratio of the shear span to the effective depth is equal to 1 and the representative shear-compression failure mode for the ratio of shear span to effective depth is 2, and have no obvious difference in failure mode for each ratio of the shear span to the effective depth. Their shear resistance mechanism is basically the same. Furthermore, based on the validated finite element model, this paper conducted a parameter extension analysis. The finite element results show that: The ultimate load bearing capacity of the steel and concrete composite beam with molybdenum tailing varies significantly with the beam section size (beam section width and beam depth), reinforcement ratio, and the ratio of the shear span to the effective depth; Whereas it has little relation to the steel plate thickness. This provides the necessity and feasibility to use the steel and concrete composite beam with the molybdenum tailing in engineering practice. The proposed equation in this study is based on the previous researches and the simulated and test results. The proposed equation is rigorous and thorough and the predicted results are highly accurate and effective.

Influence of Fiber Orientation on the Shear Properties of Steel Fiber-Reinforced Reactive Powder Concrete Beams

Steel fiber-reinforced reactive powder concrete (SFRPC) has good mechanical properties and is thus useful for engineering applications. Generally, the fibers in SFRPC are randomly distributed. To study the effects of the amount, length, and orientation of steel fibers on the shear strength of SFRPC beams, nonreinforced aligned steel fiber-reinforced reactive powder concrete (ASFRPC) beams were prepared using a large-scale electromagnetic field orientation device. Shear tests of specimens with a shear span ratio of 1.5 were performed under two fiber contents (1.0% and 2.0%) and three fiber lengths (20, 30, and 40 mm). The full-field strain during the loading process was obtained via the digital image correlation method, and the effects of fiber quantity and orientation on the shear strength of the beams were analyzed. The ASFRPC beams exhibited higher ductility but lower shear capacity than the SFRPC beams under the same conditions. The shear capacity increased with the quantity of steel fibers. According to the test results, the calculation formulas of the shear-bearing capacities of ASFRPC and SFRPC beams were established.

Experimental Study of Shear Performance of High-Strength Concrete Deep Beams with Longitudinal Reinforcement with Anchor Plate.

As a transfer member at the discontinuous place of vertical load, the deep beam has a complex stress mechanism and many influencing factors, such as compressive strength of concrete, shear span ratio, and reinforcement ratio. At the same time, the stress analysis principle of traditional shallow beams is no longer applicable to the design and calculation of deep-beam structure. The main purpose of this paper was to use the strut-and-tie model to analyze its stress mechanism, and to verify the applicability of the model. Nine high-strength concrete deep-beam specimens with longitudinal reinforcement with an anchor plate of the same size were tested by two-point concentrated loading method. The effects of shear span ratio (0.3, 0.6, and 0.9), longitudinal reinforcement ratio (0.67%, 1.05%, and 1.25%), horizontal reinforcement ratio (0.33%, 0.45%, and 0.50%), and stirrup reinforcement ratio (0.25%, 0.33%, and 0.50%) on the failure mode, deflection curve, characteristic load, crack width, steel bar, and concrete strain of the specimens were analyzed. The results showed that the failure mode of deep-beam specimens was diagonal compression failure. The normal section cracking load was about 15 to 20% of the ultimate load, and the inclined section cracking load was about 30~40% of the ultimate load. The shear span ratio increased from 0.3 to 0.9, and the bearing capacity decreased by 32.9%. When the longitudinal reinforcement ratio increased from 0.67% to 1.25%, the ultimate load increased by 42.6%. The shear span ratio and longitudinal reinforcement ratio have a significant effect on the bearing capacity of the high-strength concrete deep beams with longitudinal reinforcement with an anchor plate. The shear capacity of nine high-strength concrete deep-beam specimens with longitudinal reinforcement with an anchor plate was calculated by national standards, and the results were compared with the calculation results of the Tan-Tang model, the Tan-Cheng model, SSTM, and SSSTM. The analysis showed that the softened strut-and-tie model takes into account the softening effect of compressive concrete, and is a more accurate mechanical model, which can be applied to predict the shear capacity of high-strength concrete deep-beam members with longitudinal reinforcement with an anchor plate.

Research on seismic performance of ITRAC-filled double steel plate composite shear wall

The iron tailings and recycled aggregate concrete(ITRAC)-filled double steel plate composite shear wall (ITRAC-CSW) is a new lateral force-resistant member that applies an optimized cross-sectional form. The ITRAC is recycled concrete produced from 100% solid waste aggregates. Three full-scale ITRAC-CSW specimens were fabricated to investigate the effects of axial compression ratio and shear span ratio on seismic performance by conducting the tests subjected to quasi-static load. The failure mode and the hysteretic performance of the specimens are analyzed. The ITRAC-CSW exhibits good bearing capacity, stiffness, and energy dissipation capacity. This indicates that ITRAC has the potential to replace concrete applications. The numerical simulations and parametric analyses were carried out through the finite element model to reveal the failure mechanism and parameter effects of specimens. Finally, the calculation method for the bearing capacity of ITRAC-CSW was proposed based on the confined strength of the ITRAC. The ratio of the calculated bearing capacity to the test results is between 0.901 and 1.097 and the calculation accuracy is within 10%. This calculation method can be a reference for the performance design of ITRAC-CSW.

Prediction of the cyclic rotation capacity of steel members with cold‐formed hollow cross‐section

AbstractCold formed Hollow Structural Sections (HSS) are widely used in structural applications, especially in multi‐storey buildings located in seismic areas because of their high strength‐to‐weight ratio and torsional stiffness. However, the current version of the European seismic code provides limited rules and guidance to evaluate the ductility and the plastic rotation capacity of HSS members. The research activity carried out in this study aims to develop formulations to predict both the deformation capacity and the overstrength of cold formed HSS beams and columns at significant damage and near collapse limit states. Therefore, parametric finite element simulations have been carried out on a large set of members with different cross section (i.e., both square and rectangular HSSs), local and global slenderness, shear span and axial load ratio (from 0 to 0.5). The adopted finite element models have been calibrated against results of cyclic experimental tests available from the literature. The accuracy of the proposed equations has been statistically verified and discussion of practical applications is also provided.

Shear strength of recycled aggregate concrete beams without shear reinforcement

Steel fibers have recently become increasingly popular for strengthening reinforced concrete members. This research contains a study of shear strength under the effect of replacing 50% of natural coarse aggregate (gravel) with recycled aggregate (crushed brick) as well as the effect of steel fibers for natural aggregate concrete and recycled aggregate concrete. Five concrete beams with dimensions of 2000 mm in length, 300 mm in depth, and 200 mm in width were tested to evaluate the effect of recycled aggregates and to evaluate the efficiency of steel fibers in improving the shear capabilities of concrete beams. Beams are designed to fail due to shear stresses (without shear strengthening). The specimens were reinforced with four 4" X 16" steel bars at the bottom and two 2" X 10" steel bars as top reinforcement. Three volumetric fractions of steel fibers were used: 0%, 0.5%, and 1%. The samples were subjected to a two-point loading test. The beam samples have a ratio of shear span to effective depth (a/d) equal to 2. The results showed that replacing 50% of natural aggregate with recycled aggregate decreased ultimate shear strength, but adding steel fibers by 1% by volume resulted in an increase of 31.8% in shear strength for a recycled concrete beam. For ordinary concrete, the final shear strength increased by 18.3% and 30.8% when steel fibers were added by 0.5% and 1%, respectively. Moreover, the results also showed that the failure mode of all samples is the shear failure mode.

An experimental study on RC beams shear-strengthened with Intraply Hybrid U-Jackets Composites monitored by digital image correlation (DIC)

Reinforced concrete (RC) beams are commonly strengthened using steel stirrups, but these materials have limitations such as added weight and susceptibility to corrosion. Fiber-reinforced polymers (FRPs) offer a promising alternative to steel stirrups with high mechanical performance, low density, and resistance to corrosion and chemicals. In particular, Intraply Hybrid Composites (IRCs), which comprise multiple fibers oriented in different directions within a single matrix, have recently gained attention in the construction industry. Cakir et al. [1] investigated the use of three types of IRCs (Aramid-Carbon (AC), Glass-Aramid (GA), and Carbon-Glass (CG)) for strengthening 2-meter-long RC beams (the ratio of shear span (a) to effective depth (d) equals 3 (a/d = 3)) against shear fractures. In this study, the effects of these IRCs on the shear strength of 1.5-meter-long RC beams (a/d = 2) without transverse reinforcement were examined. In this scope, four-point bending tests were conducted on the beams after U-shaped IRC strengthening, and the impact of IRCs on shear strength was evaluated using both digital image correlation and classical measurement equipment such as strain gauges and linear variable differential transducers. The maximum load measured in RC1.5 was 194.50 kN, while the ultimate load capacity reached 265 kN in AC1.5, 246 kN in GA1.5, and 229 kN in CG1.5 after strengthening, representing increases of 36%, 26%, and 18%, respectively, compared to RC1.5. Additionally, the maximum mid-span deflections were determined as 30.40 mm, 16.10 mm, 22.20 mm, and 36.40 mm for RC1.5, AC1.5, GA1.5, and CG1.5, respectively. Moreover, the experimental results were compared with the predictions obtained from the international codes. It should be noted that the failure modes of RC beams are directly affected by the type of IRCs used, highlighting the significant contribution these materials can make to the structural behavior of RC beams.

Experimental Investigation of Shear Behavior in High-Strength Concrete Beams Reinforced with Hooked-End Steel Fibers and High-Strength Steel Rebars

Shear failure is an unfavorable phenomenon as it is a brittle type of failure; however, adding rebars and fibers to a concrete beam can minimize its detrimental effects. The objective of this study was to experimentally investigate the shear behavior of high-strength concrete (HC) beams reinforced with hooked-end (H) steel fibers and high-strength steel (HS) rebars under three-point bending tests. For this purpose, nine HC beams (300 × 250 × 1150 mm in dimension) were cast with 0%, 1%, and 2% H fibers by volume in three longitudinal rebar ratios (i.e., 1.5%, 2.0%, and 3.1%) and compared with beams without fibers. Furthermore, numerical analyses were performed to validate the experimental results and compare them with design codes. The results showed that, irrespective of the fiber content or longitudinal rebar ratio, the beams failed in shear. Increasing the rebar ratio and fiber content increased the shear capacity to as high as 100% (for the specimen with 3% rebar and 2% fiber compared to its counterpart with 1% rebar and 2% fiber). In addition, the research-based equations proposed in the literature either overestimated or underestimated the shear capacity of fibrous HC beams significantly. The level of overestimation or underestimation was closely related to the sensitivity of the proposed model to the shear span ratio and the fiber content. Rebars proved to be more beneficial in contributing to the shear capacity, but the rate of this positive contribution decreased as the fiber ratio increased. Finally, the inverse analysis approach adopted herein proved to be an efficient tool in estimating the shear response of fiber-reinforced beams failing in shear (margin of error: less than 10%).

Size effect tests on shear strength of Basalt FRP-RC deep beams with different shear-span ratios

Basalt Fiber Reinforced Polymer (BFRP) bars appear effective in reducing corrosion-related damage and are gradually used as substitute for Steel bars in engineering practices. However, most of available efforts are focused on the size effect of BFRP-reinforced concrete (BFRP-RC) deep beams without web reinforcement, while less efforts have been studied on BFRP-RC deep beams with web reinforcement. Moreover, the quantitative influence of the shear-span ratio on the shear capacity of BFRP-RC deep beams is always in dispute. The purpose of the work is to investigate the quantitative influence of beam depth and shear-span ratio on the shear behavior of BFRP-RC deep beams with web reinforcement. A total of sixteen specimens were tested by considering the beam depth (i.e., 300 mm ∼ 1200 mm) and the shear-span ratio (i.e., 0.8, 1.3 and 1.8) as test variables. Twelve beams were reinforced with BFRP bars while the other four beams were reinforced with steel bars to act as controls. The corresponding size effect of BFRP-RC deep beams with web reinforcement was quantitatively studied, and the applicability of current design codes and scientific calculation methods were discussed. The results indicate that: 1) the increase of shear-span ratio reduces the nominal ultimate shear strength but has an ignorable influence on the size effect; 2) the nominal ultimate shear strength of BFRP-RC deep beams declinebyabout 46% as the beam depth increases from 300 mm to 1200 mm (both horizontal and vertical web reinforcement ratio are 0.51%); 3) the size effect of FRP-RC deep beams is not reasonably considered in current design codes, while, Jin’s theoretical model can scientificallyreflect the effect of beam depth and shear-span ratio on the nominal shear strength.

Finite element analysis of seismic behavior of PVA-ECC pier columns based on ABAQUS

In order to study the seismic performance of PVA-ECC pier column, using the finite element analysis software ABAQUS as the main research means, combined with the measured data of two existing specimens, and taking the axial compression ratio, shear span ratio and stirrup spacing as changing parameters, the extended analysis of 13 specimens was carried out, and the influence of various influencing parameters on the seismic performance of pva-ecc pier column was discussed. The results show that the established ABAQUS finite element model has a high degree of coincidence in failure morphology, hysteretic curve, skeleton curve and stiffness degradation curve; The shear span ratio and axial compression ratio have a great influence on the type performance of PVA-ECC pier column. The influence of stirrup diameter on shear capacity is less than 5%.

Shear performance test and nominal bearing capacity on the transfer beams of steel reinforced concrete in subway station structure

To investigate the shear behaviors of steel reinforced concrete (SRC) transfer beams in subway station structure, the shear performance tests of 13 specimens on the transfer beams were investigated under the concentrated loads. The design parameter variables of transfer beams in the experiments main included the shear span ratio, profile steel ratio and section form of profile steel. The failure modes, load–displacement curves and strain characteristics of transfer beams were also analyzed in detail. The results show that the vertical cracks appeared in the transfer beams firstly, then the main oblique cracks appeared on both sides of the middle span of transfer beams, and finally the concrete at the support and the loading point of transfer beams fell off due to the shear action, which was a typical shear failure. Compared with reinforced concrete (RC) transfer beams, the shear bearing capacity and ductile deformation ability of SRC transfer beams have been significantly improved, and the shear bearing capacity of SRC transfer beams is 112.05% higher than that of RC transfer beams at the same shear span ratio. Reducing the shear span ratio can enhance the shear bearing capacity of transfer beams, but it is not good for their ductility. With the profile steel ratio from 5.41 % to 5.89 %, the shear bearing capacity of channel steel reinforced concrete transfer beams and I-shaped steel reinforced concrete transfer beams increases by 11.81 % and 12.14 % respectively. However, the section form of profile steel has less influence on the shear behavior of transfer beam. According to the mechanical properties and failure mechanism of SRC transfer beams, the calculation formulas on the shear bearing capacity of SRC transfer beams was proposed based on the truss-arch model. The calculation accuracy on the modified formulas of SRC transfer beams were evaluated by the comparison between the calculated values and test values.

Shear behaviour of SWSS-SCC beams reinforced with GFRP bars and Stirrups: Experimental and analytical investigations

This paper presents a study of shear behaviour of sea-water and sea sand self-compacting concrete (SWSS-SCC) beams reinforced with glass fibre reinforced polymer (GFRP) bars and stirrups. Nine full-scale beams were conducted and tested under four-point loading up to failure. The investigated experimental variables were the shear-span ratio, configuration of GFRP stirrups, type of the concrete, longitudinal reinforcement ratio and beam depth. The crack pattern, failure mode, load–deflection response, load–strain response and shear capacity of concrete beams were discussed. It is evident in the test results that the ultimate shear capacity of test specimens is enhanced by reducing the shear-span ratio, using the GFRP stirrups, improving the longitudinal FRP reinforcement ratio and increasing the beam depth. The shear behaviours of SWSS-SCC beam reinforced by GFRP bars and stirrups were found to be similar to that of fresh-water and river sand self-compacting concrete (FWRS-SCC) beam. The ultimate shear capacity of the test beams was predicted by the theoretical models reported in the literature. In addition, the effect of the experimental parameters on shear capacity was discussed and the theoretical models of shear strength were evaluated based on the summarized database. It is found that the nominal shear strength is barely affected by the axial compressive strength and is optimal when the longitudinal reinforcement ratio is about 2%. The CSA-S806 2012 specification has more accurate prediction results for the shear capacity of concrete beams reinforced with FRP bars and stirrups.

Seismic behavior of shear walls partially strengthened with UHPC in boundary element

Inspired by studies on shear walls reinforced with high performance cement-based materials, this paper explores the applicability of ultra-high performance concrete (UHPC) for improving the seismic behavior of shear walls. In this study, a novel shear wall partially strengthened with UHPC in the boundary element was developed, in which the UHPC was cast into the potential plastic hinge region of the boundary element. Partial application of UHPC can reduce construction costs and promote its use in building structures. To study the influence of distribution height and width of UHPC and axial load ratio on the seismic performance, six shear walls with a shear span ratio of 2.1 were tested under axial load and cyclic lateral load. The failure modes, lateral load-lateral displacement hysteretic behavior and ductility of the shear walls were also investigated. The experimental results indicated that the partial application of UHPC in boundary elements could effectively improve the performance of shear walls. Moreover, even if the volume ratio of UHPC was only 0.12, the shear wall partially strengthened with UHPC still showed good seismic performance under a high axial load ratio, indicating that this type of shear wall can be applied to the high seismic intensity and high axial load ratio regions.

Behaviour of recycled aggregate concrete-filled stainless steel tubular columns subjected to lateral monotonic and cyclic loading

This paper presents a series of experimental research on recycled aggregate concrete-filled stainless steel tubular (RAC-FSST) columns subjected to lateral monotonic and cyclic loading. The influence of axial load level, shear span ratio, and replacement ratio of recycled coarse aggregate on the RAC-FSST members under compression-bending loads is studied. The test results indicate that the RAC-FSST columns exhibit favorable ductility and energy dissipation capacity. The P-Δ skeleton curves of the columns subjected to lateral cyclic loading are similar to those of columns under monotonic loading. It indicates that, compared with the plastic damage of the concrete, the cyclic hardening characteristics of the stainless steel have more significant influence on the bearing capacity. Considering the characteristics of material loading and unloading criteria, a FE model is established to analyze the seismic performance of RAC-FSST, with the internal force development and stress distribution discussed. Based on the parametric analysis, the modification method of bearing capacity and the hysteretic models of RAC-FSST members are proposed.

Quasi-static tests of squat reinforced concrete shear walls with openings

Due to the high level of stiffness and strength, Squat Reinforced Concrete Shear Walls (SRCSWs) with or without openings are frequently utilized in various types of buildings. However, the adverse effect of openings on the seismic performance of the SRCSWs has never been investigated in detail. Therefore, for truly disclosing the seismic behaviors of the SRCSWs with openings, six 1/2.7 scale SRCSW specimens are experimentally investigated through Quasi-Static Testing (QST) in this paper. The affecting factors in terms of the Shear Span Ratio (SSR), the area ratio, and the number of openings are considered. Based on the experimental results, the seismic performance in terms of failure modes, hysteretic loops, skeleton curves, ductility factors, stiffness degradations, energy dissipations, and deformation components was analyzed and discussed. It is shown that shear failure was observed on the SRCSWs without openings, while the SRCSWs with openings are prone to flexural failure, e.g., the flexural deformation ratios ranging from 49.66% to 58.99%. It is shown from the experimental results that the area ratio and the SSR significantly affect the seismic response of SRCSWs, generally speaking, with the increase of the area ratio and/or SSR the bearing capacity and the secant stiffness are reduced. It is also shown that for the case of multi-openings, the cracks are focused on the connecting areas between two openings. The results indicate that the seismic design of SRCSWs should consider the effect of openings in order to enhance the seismic performance.

Flexural behavior and design methodology for bamboo scrimber-aluminum plate composite beams

This paper presents a study on the flexural behavior of twelve bamboo scrimber-aluminum plate composite beam specimens. The research investigates the effects of aluminum plate thickness and shape on specimen failure mode, flexural moment–curvature relations, and flexural capacity. Finite element (FE) analysis is used to benchmark test results. The study also includes parametric studies that explore the impact of various factors such as aluminum yield strength, plate thickness, adhesive shear strength, shear span ratio, and depth to width ratio on the flexural capacity of the specimens. The results indicate that while increasing the yield strength of aluminum plate has little effect on flexural stiffness and capacity, increasing plate thickness significantly improves these characteristics in the service limit state. Additionally, increasing the depth-width ratio and shear span ratio correspondingly improves flexural stiffness and capacity. The shear strength of adhesive has a significant impact on flexural capacity, but only a minor effect on flexural stiffness during the elastic stage. Based on the parametric study, modified calculation formulae are proposed to predict the flexural capacity of composite beams with and without inter-layer slip.

Analysis of Shear Model for Steel-Fiber-Reinforced High-Strength Concrete Corbels with Welded-Anchorage Longitudinal Reinforcement.

According to the shear capacity test results of six steel-fiber-reinforced high-strength concrete (SFHSC) corbels with welded-anchorage longitudinal reinforcement under concentrated load, the effects of shear span ratio and steel fiber volume fraction on the failure mode, cracking load and ultimate load of corbel specimens were analyzed. On the basis of experimental research, the shear transfer mechanism of corbel structure was discussed. Then, a modified softened strut-and-tie model (MSSTM), composed of the diagonal and horizontal mechanisms, was proposed, for steel-fiber-reinforced high-strength concrete corbels. The contributions of concrete, steel fiber and horizontal stirrups to the shear bearing capacity of the corbels were clarified. A calculation method for the shear bearing capacity of steel-fiber-reinforced high-strength concrete corbels was established and was simplified on this basis. The calculation results of the model were compared with the test values and calculation results of the GB50010-2010 code, the ACI318-19 code, the EN 1992-1-1 code and the CSA A23.3-19 code. The results showed that the concrete corbel with small shear span ratio mainly has two typical failure modes: shear failure and diagonal compression failure. With the increase in shear span ratio, the shear capacity of corbels decreases. Steel fiber can improve the ductility of a reinforced concrete corbel, but has little effect on the failure mode of the diagonal section. The calculated values of the national codes were lower than the experimental values, and the results were conservative. The theoretical calculation values of the shear capacity calculation model of the corbels were close to the experimental results. In addition, the model has a clear mechanical concept considering the tensile properties of steel-fiber-reinforced high-strength concrete and the influence of horizontal stirrups, which can reasonably reflect the shear transfer mechanism of corbels.

Dynamic response of concrete-filled square steel tubular columns under lateral impact load at flat or corner zone

The dynamic response of columns under lateral impact is of great significance for guiding structural design under accidental loads. The present study aims to investigate the effect of different impact directions on the dynamic response of square concrete-filled steel tubular (CFST) columns by conducting drop hammer tests at flat or corner zones. The main experimental parameters included hammer mass, drop height, indenter radius, built-in steel bars, shear span ratio, width-thickness ratio, and column sizes. The experimental results showed that the impact zone has a significant effect on the dynamic response of CFST specimens. Under higher impact energies, specimens impacted at corner zones were more likely to fracture on the tensile side of the steel tube than specimens impacted at flat zones. And the specimens impacted at the corner zone were more sensitive to the change of indenter radius. Smaller shear span ratios, built-in steel bar, and larger column sizes improved the impact resistance of tested specimens. The 3D finite element models were developed and analyzed by ABAQUS/Explicit to explore dynamic behavior further.