Confinement limits for tension lap slices under static loading

1992 ◽  
Vol 19 (3) ◽  
pp. 447-453 ◽  
Author(s):  
T. Rezansoff ◽  
U. S. Konkankar ◽  
Y. C. Fu
Keyword(s):  
Static Loading ◽  
American Concrete Institute ◽  
Concrete Cover ◽  
Transverse Reinforcement ◽  
Lap Splices ◽  
Lap Splice ◽  
Current Limit ◽  
Concrete Confinement ◽  
Bar Diameter ◽  
Concrete Reinforcement

In tension lap splices, the benefit provided to the lap by stirrups placed to intercept longitudinal cracking due to bond splitting action is recognized by the American Concrete Institute code (ACI 318-89) and the design recommendations of ACI Committee 408, on which the American code provisions are partially based. However, a limit exists on the benefit that can be derived from this confinement. In Canada, Canadian Standards Association Standard CAN3 A23.3 M-84 does not directly recognize the confinement benefit provided by stirrups placed along a lap splice. The current study shows that the ACI limit of 1 bar diameter of equivalent concrete cover provided by the transverse reinforcement confinement is too restrictive under static loading. When the concrete cover is small, much larger transverse reinforcement confinement, up to 2-2.5 bar diameters of equivalent concrete cover, can be utilized, in lieu of requiring very long lap lengths. The tests also show that total confinement (actual concrete confinement plus equivalent concrete confinement provided by stirrups) is effective beyond the current limit of 3 main bar diameters, when stirrups are provided. Good performance was found with confinements of 4-4.5 bar diameters, and correspondingly shorter lap splice lengths. Key words: concrete, reinforcement, lap splices, beams, confinement, stirrups, tension, static loading.

scholarly journals Local Behavior of Lap-Spliced Deformed Rebars in Reinforced Concrete Beams

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7186
Author(s):  
Agha Syed Muhammad Gillani ◽  
Seung-Geon Lee ◽  
Soo-Hyung Lee ◽  
Hyerin Lee ◽  
Kee-Jeung Hong
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
American Concrete Institute ◽  
Reinforced Concrete Beams ◽  
Local Behavior ◽  
Test Results ◽  
Loading Test ◽  
Lap Splices ◽  
Lap Splice ◽  
Ductile Behavior

Twelve full-scale reinforced concrete beams with two tension lap splices were constructed and tested under a four-point loading test. Half of these beams had shorter lap splices than that recommended by American Concrete Institute Building Code ACI 318-19; they failed by bond loss between steel and concrete at the lap splice region before rebar yielding. The other half of the beams were designed with a lap splice length slightly exceeding that recommended by ACI 318-19; they failed by rebar yielding and exhibited a ductile behavior. Several strain gauges were attached to the longitudinal bars in the lap splice region to study the local behavior of deformed bars during loading. The strain in a rebar was maximum at the loaded end of the lap splice and progressively decreased toward the unloaded end because the rebar at this end could not sustain any load. Stress flow discontinuity occurred at the loaded end and caused stress concentration. The effect of this concentration was investigated based on test results. The comparison of bond strengths calculated by existing equations and those of tested specimens indicated that the results agreed well.

scholarly journals High cycle (fatigue) resistance of reinforced concrete beams with lap splices

1993 ◽  
Vol 20 (4) ◽  
pp. 642-649 ◽  
Author(s):  
Telvin Rezansoff ◽  
James A. Zacaruk ◽  
Jeffrey G. Afseth
Keyword(s):  
Static Loading ◽  
Fatigue Loading ◽  
Reinforced Concrete Beams ◽  
Bond Failure ◽  
Lap Splices ◽  
Lap Splice ◽  
Major Variable ◽  
Effective Depth ◽  
High Degree ◽  
Tension Loading

Full-scale specimens were tested so that lap spliced bottom bars were subjected to cyclic tension loading. The major variable was the degree of transverse confining reinforcement (stirrups) provided along the lap. Lap splices were confined either with the maximum transverse reinforcement deemed to be effective for static loading, permitting the use of shorter lap splice lengths, or with stirrups spaced at approximately one half the effective depth of the beam, requiring the use of a longer lap length. Failure in all specimens with heavier stirrups (shorter laps) occurred with fatiguing of the reinforcing steel, showing fatigue resistances that were comparable with the results for continuous bars tested in flexure. With the lighter (nominal) stirrups, fatigue loading usually produced a splice failure, where the confining concrete split away from the lap in a typical bond failure after fewer load cycles. For comparable bond resistance under static loading, the beams with the heavier stirrup confinement along a shorter lap length were superior under fatigue loading. As previously shown with low cycle, high intensity reversal (seismic) loading, the current study shows that it is prudent to provide a high degree of transverse reinforcing confinement to lap splices that are subjected to fatigue loading. Key words: concrete, reinforcement, lap splices, fatigue, bond, beams, confinement, stirrups, tension.

Effectiveness of concrete confinement on lap splice performance in concrete beams under reversed inelastic loading

1989 ◽  
Vol 16 (1) ◽  
pp. 36-44
Author(s):  
B. MacKay ◽  
D. Schmidt ◽  
T. Rezansoff
Keyword(s):  
Reinforced Concrete ◽  
Seismic Design ◽  
Concrete Beams ◽  
Reinforced Concrete Beams ◽  
Repeated Loading ◽  
Transverse Reinforcement ◽  
Cornell University ◽  
Lap Splice ◽  
Concrete Confinement ◽  
Load Cycling

Proposals from Cornell University for seismic design of lap splices, where the strength provided to the lap splice by the concrete confinement is considered insignificant, were evaluated. The concrete confining the splice length is assumed to deteriorate after high-intensity (inelastic) reversed load cycling so that the performance is mainly dependent on the amount of transverse reinforcement provided to confine the lap splice. Lap lengths of 30–40 bar diameters are proposed, along with heavy transverse reinforcement. Longer lap lengths are considered to be less effective. By contrast, for static loading the concrete confining the splice is known to play a major role in transferring load between the bars along the splice.The current program consisted of testing six reinforced concrete beams under fully reversed cycled loading. The three similar beams in each of the two series contained equal stirrup confinement (number of stirrups) along the lap length to satisfy the Cornell University recommendations for seismic loading for the measured reinforcing yield strength, while the splice length was varied. Splices were located in the bottom face of the test beams and were positioned in a region of maximum moment to ensure severe stressing. Each series of specimens exhibited only small strength gains with increasing splice lengths; however, the performance, when evaluated on the basis of the ductility achieved and the hysteretic energy absorbed prior to failure, was superior with long splices. Since the main reinforcement in the test beams was loaded past yielding, large increases in deformation capacity resulted in only small increases in load.Full reversal inelastic load cycling is very detrimental to the concrete that confines the splice region when compared to static (monotonic) loading or one-directional repeated loading to failure. Splice failure loads under reversal loading in the current study were below predicted static strengths for the same beam configurations, and with the longer lap lengths, static failure would have been flexural rather than in the splice. Key words: reinforced concrete, beams, splices (lap), confinement, seismic design, cycled loading, ductility, strength.

scholarly journals The method of analysis of a reinforced concrete section under bending in the post-yield range

2013 ◽  
Vol 12 (1) ◽  
pp. 123-130
Author(s):  
Jacek Korentz
Keyword(s):  
Reinforced Concrete ◽  
Analytical Procedure ◽  
Concrete Cover ◽  
Transverse Reinforcement ◽  
Concrete Members ◽  
Extreme Loads ◽  
Concrete Confinement ◽  
The Moment ◽  
The Relationship ◽  
Concrete Section

Predicting the behavior of plastic hinges subjected to large inelastic deformations caused by extreme loads such as earthquakes plays an important role in assessing maximum stable deformation capacities of framed concrete structures. This paper presents an analytical procedure for analysing the behaviour of a reinforced concrete section under bending in the post-yield range. The following stages of section behaviour are defined as the uncracked; first cracked; yielding; cover crushing; cover spalling; buckling of bars; and limit stages. The relationship between the moment and curvature in these stages, including the effects of concrete confinement, the spalling of the concrete cover, and the inelastic buckling of the reinforced bars, are considered. The results obtained from analytical calculations have are compared to the results obtained from a computer analysis. The presented method makes it possible to estimate the ductility of reinforced concrete members with various longitudinal and transverse reinforcement.

scholarly journals Performance of Tension Lap-Splice in Lightweight Concrete

2020 ◽  
Vol 9 (3) ◽  
pp. 181-186
Keyword(s):  
Failure Modes ◽  
Lightweight Concrete ◽  
Cost Savings ◽  
Concrete Cover ◽  
Steel Reinforcement ◽  
Moment Capacity ◽  
Bond Behavior ◽  
Lap Splice ◽  
Cover Thickness ◽  
Bar Diameter

The use of Light-Weight Concrete (LWC) in modern construction has resulted in efficient designs and considerable cost savings by reducing structural own weight and supporting footings sections. The purpose of this paper is to investigate the Lap-Splice behavior between LWC and steel reinforcement (RFT). The tested specimens were divided into four groups to study the effect of main variables: steel reinforcement bar size, internal confinement (stirrups), splice length and concrete cover thickness. Four-point bending tests were carried out on test specimens to evaluate the performance of lap splices under pure bending. Bond behavior and failure modes were noted to be similar in the normal concrete and in the LWC. In tested beams, it was observed that the bar size has a significant influence on the mean bond stress in the splice. Improving radial tensile strength by using increasing stirrups number improves the bond behavior. The splice length up to 35 times bar diameter decreased the moment capacity of beam. The splice length of 55 times bar diameter results in the same capacity of the beam without any splice.

Stirrup distribution across the beam width in tension lap splices

1999 ◽  
Vol 26 (1) ◽  
pp. 83-95 ◽  
Author(s):  
K Pacholka ◽  
T Rezansoff ◽  
B F Sparling
Keyword(s):  
Static Loading ◽  
Beam Width ◽  
Static Fatigue ◽  
Test Results ◽  
Slight Improvement ◽  
Fatigue Load ◽  
Lap Splices ◽  
Lap Splice ◽  
Load Cycling ◽  
Transverse Steel

The influence of the distribution of transverse confining steel on the strength of tension lap splices was investigated experimentally in this study. Beam specimens contained three lap-spliced No. 35 bars placed in one layer. Either two or three stirrup legs were placed across the beam width to provide splitting confinement. Both configurations were designed to provide similar stirrup resistances for intercepting horizontal bond splitting. The effectiveness of the different stirrup configurations was compared by investigating the performance of beams subjected to static, fatigue, and fully reversed inelastic loading. Twenty-three full-size beam specimens were tested with the lap splice placed symmetrically within a maximum moment, zero-shear region. Specimens were constructed and tested in six different series (concrete batches). Within each series, the total bond resistance, as evaluated on the basis of CSA A23.3-94, was similar even though the lateral distribution of transverse steel was varied. Nine specimens were tested under monotonically increasing (static) loading to failure, six specimens were subjected to fatigue load cycling between 25% and 75% of their ultimate static strength, and eight specimens were subjected to fully reversed inelastic load cycling. Test results for six similar specimens from a previous study were also included in the current investigation analysis. Test results indicated that using three vertical stirrup legs across the beam width to provide a more uniform distribution of stirrup confinement significantly enhances post yield ductility under fully reversed inelastic load cycling. Meanwhile, specimens tested under static loading showed that CSA A23.3-94 provisions provide a consistent and conservative prediction of lap-splice strength for the specimen configurations investigated, regardless of the distribution of stirrup confinement across the beam width. Finally, the performance of fatigue specimens indicated a slight improvement with the use of the three-leg stirrup configuration. However, this result does not agree with previous observations made at the same institution where it was suggested that stirrup confinement intercepting vertical splitting plays a more significant role in defining fatigue resistance.Key words: reinforced concrete, bond, confinement, lap splices, stirrups, static loading, fatigue load cycling, inelastic load reversal.

scholarly journals Behavior and Splice Length of Deformed Bars Lapping in Spirally Confined Grout-Filled Corrugated Duct

2019 ◽  
Vol 2019 ◽  
pp. 1-11
Author(s):  
Yongfeng Zheng ◽  
Zhangfeng Zhu ◽  
Zhengxing Guo ◽  
Peng Liu
Keyword(s):  
Tensile Strength ◽  
Reduction Factor ◽  
Experimental Results ◽  
Dominant Effect ◽  
Bond Failure ◽  
Lap Splices ◽  
Lap Splice ◽  
Pitch Distance ◽  
Bar Diameter ◽  
Corrugated Duct

This paper discusses the behavior of grouted noncontact lap splices under monotonic tension load. Deformed bars lapped through a grout-filled corrugated duct, and a spiral reinforcement was preembedded in the connection to improve tensile strength of the splice. The experimental results show that bond failure splices are always failed by the pullout of the preembedded bar other than the grouted bar. As the spiral pitch distance is not greater than 75 mm, the tensile strength generally improves with the increment of volumetric spiral reinforcement ratio due to the higher confinement provided by the spiral bar. Compared with the spiral bar diameter, the spiral pitch distance provides more dominant effect on the tensile strength of the connection. Based on the experimental results and the development length specified in ACI 318-14, a revised equation with a reduction factor of 0.76 was proposed to predict the required minimum lap length of spirally confined lap splice.

Correlation of the bond provisions of CSA A23.3-94 with tests on tension lap splices in beams

1995 ◽  
Vol 22 (4) ◽  
pp. 755-769 ◽  
Author(s):  
T. Rezansoff ◽  
B. F. Sparling
Keyword(s):  
Static Loading ◽  
Factor Of Safety ◽  
Accurate Estimate ◽  
Development Length ◽  
Structural Bond ◽  
Lap Splices ◽  
Lap Splice ◽  
Wide Range ◽  
Modification Factor ◽  
Definition Of

Data on beams with tension lap splices tested under static loading at the same institution over the past two decades are correlated with the bond provisions of the Canadian concrete standard CAN/CSA A23.3-94 (detailed design approach), as well as with the recommendations of ACI Committee 408, on which the Canadian standard appears to be largely based. The correlations show that transverse reinforcement is more effective than the new bond provisions allowed in cases where the bond failure is governed by splitting rather than bar pullout. Extending the effective limits for confinement provides a more accurate estimate of the bond resistance available at higher levels of confinement, resulting in a more uniform factor of safety over a wide range of confinements. Lap splices with no transverse confinement showed relatively poorer performance than lap splices with varying degrees of transverse confinement when correlated with resistances predicted on the basis of the new CAN/CSA A23.3-94 provisions. Weaker relative splice performance in the absence of transverse confinement raises a concern for the development lengths required by the CAN/CSA A23.3-94 provisions. With highly stressed lap splices, a class factor of 1.3 is applied to the basic development length to determine the lap length. Published information, on the other hand, has shown that lap splice lengths and development lengths should be the same for transferring or developing the same level of stress in tension reinforcement when the same level of confinement is provided along the anchorage. In contrast, the ACI Committee 408 recommendations use a larger factor of safety on development length and lap splice length, rather than applying class factors for splices only, making splice and development lengths the same for the same confinement and required strength transfer. For the data considered, required lap lengths are similar using both the CSA Standard CAN/CSA A23.3-94 (including the 1.3 class factor) and the ACI 408 recommendations, and only small differences in overall prediction accuracy were found. Differences in the definition of the concrete confinement term for close bar spacing by the two design models, different limits on the total confinement that can be considered effective, as well as a further modification factor for bar size in the CAN/CSA A23.3-94 provisions, result in only small differences in lap length requirements for most of the data considered. Key words: anchorage (structural), bond, confinement, lap splices, reinforced concrete, standards, static loading, tension.

Analysis of Crack Patterns of 500MPa Reinforced Concrete Beams

2013 ◽  
Vol 790 ◽  
pp. 120-124
Author(s):  
Zhi Hua Li ◽  
Xiao Zu Su
Keyword(s):  
Static Loading ◽  
Crack Width ◽  
Concrete Beams ◽  
Concrete Cover ◽  
Reinforced Concrete Beams ◽  
Crack Control ◽  
Crack Patterns ◽  
Beam Depth ◽  
Steel Bars ◽  
Constant Moment

Fourting concrete beams reinforced with 500MPa longitudinal steel bars, of which 6 with skin reinforcement and 8 without skin reinforcement, were tested under two-point symmetrical concentrated static loading to investigate their crack patterns. Crack distributions in constant moment region of beams are compared. The propagation of side cracks along the beam depth is obtained. The results of this study indicate that the concrete cover of longitudinal tensile steel bars and the spacing of skin reinforcement has significant effect on crack distributions; substantial crack control in beams can be achieved if the spacing of skin reinforcement is limited to certain critical values. The curve of d-w(d is the distance between observation points of side cracks and tension face of beams, w refers to crack width at observation points) is approximately characterized by a zig-zag shape and concave-left near longitudinal tensile steel bars.

Seismic Behavior of Slender HPFRCC Coupling Beams with Limited Transverse Bars

2018 ◽  
Vol 34 (1) ◽  
pp. 77-98 ◽  
Author(s):  
Sang Whan Han ◽  
Jin Wook Kang ◽  
Chang Seok Lee
Keyword(s):  
Seismic Behavior ◽  
High Performance ◽  
American Concrete Institute ◽  
Transverse Reinforcement ◽  
Cement Composites ◽  
Coupling Beams ◽  
Conventional Concrete ◽  
Drift Capacity ◽  
High Performance Fiber ◽  
Reinforced Cement

The objective of this study was to investigate the seismic behavior of slender concrete diagonally-reinforced coupling beams (DRCBs) with an aspect ratio of 3.5 and to explore the possibility of alleviating the reinforcement detail for DRCBs using high-performance fiber-reinforced cement composites (HPFRCCs). For this purpose, slender HPFRCCs and conventional concrete DRCBs with transverse reinforcement spacing of 110 mm, 250 mm, and 500 mm were made and tested. One HPFRCC DRCB specimen was made without transverse reinforcement for comparison purposes. This experimental study shows that the slender HPFRRCC DRCBs with transverse reinforcement spacing of 250 mm have almost the same strength and drift capacity as those of the conventional concrete DRCB with transverse reinforcement spacing of 110 mm, satisfying the requirement of American Concrete Institute ACI 318-14 (2014) building code.

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