• Steel and Composite Structures
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• v.11 no.3
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• pp.233-250
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• 2011

An experimental study has been carried out to reveal the shear-bond failure mechanism of composite deck slabs. Thirteen full scale simply supported composite slabs are studied experimentally, with the influence parameters like span length, slab depth, shear span length and end anchorage provided by steel headed studs. A dozen of strain gauges and LVDTs are monitored to capture the strain distribution and variation of the composite slabs. Before the onset of shear-bond slip, the longitudinal shear forces along the span are deduced and found to be proportional to the vertical shear force in terms of the shear-bond strength in the m-k method. The test results are appraised using the current design procedures. Based on the partial shear-bond connection at the ultimate state, an improved method is proposed by introducing two reduction factors to assess the moment resistance of a composite deck slab. The new method has been validated and the results predicted by the revised method agree well with the test results.

• Computers and Concrete
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• v.10 no.6
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• pp.663-681
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• 2012

This paper presents a parametric study of the plastic hinge length of circular reinforced concrete columns using a three-dimensional finite element analysis method, and using the Taguchi robust design method to reduce computational cost. Parameters examined include the longitudinal reinforcing ratio, the shear span-to-depth ratio, the axial force ratio and the concrete compressive strength. The study considers longitudinal reinforcement with yield strengths of 414 MPa and 685 MPa, and proposes simplified formulas for the plastic hinge length of circular reinforced concrete columns, showing that increases in plastic hinge length correlate to increases in the axial load, longitudinal reinforcing and shear span-to-depth ratios. As concrete strength increases, the plastic hinge length decreases for the 414 MPa case but increases for the 685 MPa case.

• Steel and Composite Structures
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• v.25 no.5
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• pp.603-615
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• 2017

This experimental research presents the seismic performance of steel reinforced high-strength concrete (SRHC) short columns. Eleven SRHC column specimens were tested under simulated earthquake loading conditions, including six short column specimens and five normal column specimens. The parameters studied included the axial load level, stirrup details and shear span ratio. The failure modes, critical region length, energy dissipation capacity and deformation capacity, stiffness and strength degradation and shear displacement of SRHC short columns were analyzed in detail. The effects of the parameters on seismic performance were discussed. The test results showed that SRHC short columns exhibited shear-flexure failure characteristics. The critical region length of SRHC short columns could be taken as the whole column height, regardless of axial load level. In comparison to SRHC normal columns, SRHC short columns had weaker energy dissipation capacity and deformation capacity, and experienced faster stiffness degradation and strength degradation. The decrease in energy dissipation and deformation capacity due to the decreasing shear span ratio was more serious when the axial load level was higher. However, SRHC short columns confined by multiple stirrups might possess good seismic behavior with enough deformation capacity (ultimate drift ratio ${\geq}2.5%$), even though a relative large axial load ratio (= 0.38) and relative small structural steel ratio (= 3.58%) were used, and were suitable to be used in tall buildings in earthquake regions.

• Advances in concrete construction
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• v.13 no.2
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• pp.183-190
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• 2022

A wide range of experimental bases and improved performance with different forms of Fiber Reinforced Polymer (FRP) have attracted researchers to produce eco-friendly and sustainable structures. The reinforced concrete (RC) beam's shear capacity has remained a complex phenomenon because of various parameters affecting. Design recommendations for the shear capacity of RC elements having FRP reinforcement need a more experimental database to improve design recommendations because almost all the recommendations replace different parameters with FRP's. Steel and FRP are fundamentally different materials. One is ductile and isotropic, whereas the other is brittle and orthotropic. This paper presents experimental results of the investigation on the beams with glass fiber reinforced polymer (GFRP) reinforcement as longitudinal bars and stirrups. Total twelve beams with GFRP reinforcement were prepared and tested. The cross-section of the beams was rectangular of size 230 × 300 mm, and the total length was 2000 mm with a span of 1800 mm. The beams are designed for simply-supported conditions with the two-point load as per specified load positions for different beams. Flexural reinforcement provided is for the balanced conditions as the beams were supposed to test for shear. Two main variables, such as shear span and spacing of stirrups, were incorporated. The beams were designed as per American Concrete Institute (ACI) ACI 440.1R-15. Relation of VExp./VPred. is derived with axial stiffness, span to depth ratio, and stirrups spacing, from which it is observed that current design provisions provide overestimation, particularly at lower stirrups spacing.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.297-302
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• 2002

This paper investigated the properties of flexural behavior of composite beams (end-Reinforced concrete, center-Steel concrete) according to attaching length of main bars to flange, shear reinforcing length for different types of structure. In the preceding study, structural properties of composite beams were investigated according to shear span to depth ratio, attaching method of main bars and shear reinforcing method. Based on these results, a series of experiments was carried out according to attaching length of main bar ＆ reinforcing length for different types of structure. Consequently, as attaching length of main bar and shear reinforcing length increased, composite beams represented higher strength, ductility index and stress mechanism distributed in connection zone of different types of structure.

• Journal of the Korean Society of Safety
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• v.30 no.5
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• pp.67-73
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• 2015

In this paper, the simple truss model was modified to predict the punching shear strength of long-span prestressed concrete (PSC) deck slabs under wheel load including the effects of transverse prestressing and long span length between girders. The strength of the compressive zone arounding punching cone was evaluated by the stiffness of inclined strut which was modified by considering aging effective modulus. The stiffness of springs which control lateral displacement of the roller supports consists of the steel reinforcement and prestressing which passed through the punching cone. Initial angle of struts was determined by the experimental observation to compensate for uncertainties in the complexities of the punching shear. The validity of computed punching shear strength by modified simple truss model was shown by comparing with experimental results and the experimental results were also compared with existing punching shear equations to determine level of predictability. The modified simple truss model appeared to better predict the punching shear strength of PSC deck slabs than other available equations. The punching shear strength, which was determined by snap-through critical load of modified simple truss model, can be used effectively to examine punching shear strength of long span PSC deck slabs.

• Journal of the Korea institute for structural maintenance and inspection
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• v.6 no.4
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• pp.233-242
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• 2002

This study is to investigate experimentally the shear capacity of high-strength lightweight-aggregate reinforced concrete beams subjected to monotonic loading. Ten beams made of fly-ash artificial lightweight high-strength concrete were tested to determine their diagonal cracking and ultimate shear capacities. The variables in the test program were longitudinal reinforcement ratio; which variabled (between 0.83 and 1.66 percent), shear span-to-depth ratio (a/d=1.5, 2.5 and 3.5), and web reinforcement(0, 0.137, 0.275 and 0.554 percent). Six of the test beams had no web reinforcement and the other six had web reinforcement along the entire length of the beam. Most of beams failed brittly by distinct diagonal shear crack, and have reserved shear strength due to the lack of additional resisting effect by aggregate interlocking action after diagonal cracking. Test results indicate that the ACI Building Code predictions of Eq. (11-3) and (11-5) for lightweight concretes are unconservative for beams with tensile steel ratio of 1.66, a/d ratios greater than 2.5 without web reinforcement. Through a more rational approach to compute the contribution of concrete to the shear capacity, a postcracking shear strength in concrete is observed.

• Magazine of the Korea Concrete Institute
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• v.10 no.6
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• pp.233-240
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• 1998

A rational expression, developed to predict the shear strength of reinforced concrete beams, is derived from the relationship between shear and the rate of change of bending moment along a beam coupled with experimental findings for the arch action. The proposed ultimate shear strength equation, arising from analytical premises and then calibrated with experimental data, is a similar form to the ACI 318 equation derived mainly from empirical approach. The proposed equation depends on the concrete compressive strength, amount of longitudinal steel content, and the shear span-to-depth ratio, and rationally reflects the shear resistance mechanism of combined beam action and arch action in reinforced concrete beams. The proposed equation applied to existing test data and the results were compared with those predicted by the ACI 318 equation and the Zsutty's equation.

• Journal of Korean Society of Steel Construction
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• v.17 no.2 s.75
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• pp.151-159
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• 2005

This study investigated the capacity evaluation of composite beam of the end-reinforced concrete, the center steel with attached main-bar of stud-bolt welting and flange with main parameter, such as shear span depth ratio (a/d=1.5, 2.5, 3.5), reinforcing method, reinforcing length, and steel main-bar ratio. The test results are summarized as follows: As the RC section becomes longer, the capacity ratio of Vsrc, test/Vsrc, the gradually decreased, with the tendency of decrease being remarkably more than a/d=3.5. The reinforcing method showed superior result both vertically and horizontally. And, capacity increase ratio displayed tendency that main-bar fixing length is obvious in 0.15L, and underestimate experimental value usually in Vsrc, Eq(3)~(5) equation. The capacity estimation was proposed equation by regression analysis with change of shear span depth ratio and main-bar fixing, steel main-bar ratio.

• Journal of the Korean Society of Visualization
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• v.11 no.2
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• pp.46-54
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• 2013

Study of the wave structure and shear layer in the vicinity of a wall mounted cavity is done by time averaged colour schlieren and time resolved instantaneous shadowgraph technique in an M=1.7 flowfield. Effect of change of cavity width on flow structure is investigated by using constant length to depth (L/D) ratio cavity models with varying length to width (L/W) ratio of 0.83 to 4. The time averaged shock wave structure was observed to change with change in cavity width. Dependence of the shock angle at the leading edge on the shear layer width is also evident from the images obtained. Unsteadiness in the flow field in terms of shear layer dynamics and quasi steady nature of shock waves was evident from the images obtained during instantaneous shadowgraph experiments. Apart from the leading and trailing edge shocks, several other waves and flow features were observed. These flow features and the associated physical phenomena are discussed in details and presented in the paper.