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.

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.

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.

The performance of corroded lap splices in reinforced concrete beams

2019 ◽  
Vol 37 (1) ◽  
pp. 31-44
Author(s):  
Stavroula J. Pantazopoulou ◽  
Michael F. Petrou ◽  
Vasiliki Spastri ◽  
Nikos Archontas ◽  
Christos Christofides
Keyword(s):  
Shear Failure ◽  
Contact Length ◽  
Reinforced Concrete Beams ◽  
Fiber Reinforced Polymers ◽  
Experimental Program ◽  
Reinforced Polymers ◽  
Study Region ◽  
Lap Splices ◽  
Lap Splice ◽  
Cover Cracking

AbstractThis article presents the results of an extensive experimental program containing 22 beams with tension lap splices in the central region. The beams were preconditioned under simulated corrosion up to specific levels of bar section steel loss and cover cracking in the lap region. They were subsequently tested under four-point loading so as to place the corroded lap splice zones in tension. To prevent corrosion outside the study region, the beams were wrapped with fiber-reinforced polymers outside the laps – this also served to protect them from premature shear failure as the objective was to study failure in the lap zone. The objective of the experiment was to assess the residual anchorage capacity of such zones. The parameters of the experimental study were the extent of corrosion and the available length of lap splicing of longitudinal tension reinforcement. Corroded bond strength was determined from the short-length lap splices, where it may be assumed that stresses are uniformly distributed over the lapped zone; longer specimens were considered in order to examine how the redundancy provided by the longer contact length may improve the resilience and deformation capacity of the corrosion-damaged component prior to bond failure.

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.

Testing Research for Deformation and Rigidity of Lightweight Aggregate Reinforced Concrete Beams under Fatigue Loading

2012 ◽  
Vol 204-208 ◽  
pp. 3123-3127
Author(s):  
Guang Yu Lei ◽  
Chang Hong Wu ◽  
Shi Ming Li
Keyword(s):  
Reinforced Concrete ◽  
Static Loading ◽  
Concrete Beam ◽  
Concrete Beams ◽  
Lightweight Aggregate ◽  
Fatigue Loading ◽  
Reinforced Concrete Beam ◽  
Reinforced Concrete Beams

Through the experiment of eight lightweight aggregate reinforced concrete beams under static loading and fatigue loading with constant amplitudes, the deformation rule under fatigue loading was analysed, the rigidity calculation means and formulations of lightweight aggregate reinforced concrete beam under fatigue loading were also discussed.

Bar size factors for lap splices in block walls subjected to flexure

2015 ◽  
Vol 42 (8) ◽  
pp. 521-529
Author(s):  
Roanne D. Kelln ◽  
Lisa R. Feldman
Keyword(s):  
Experimental Investigation ◽  
Test Data ◽  
Concrete Block ◽  
Masonry Walls ◽  
Reinforcing Bars ◽  
Bond Failure ◽  
Lap Splices ◽  
Lap Splice ◽  
Out Of Plane

An experimental investigation was conducted to evaluate bar size factors used for the calculation of required lap splice lengths according to US and Canadian codes for concrete block masonry walls subjected to out-of-plane loads. Wall splice specimens were constructed in running bond with all cells fully grouted, and were tested under monotonically increasing four-point loading. Specimens were longitudinally reinforced with either No. 15, 20, or 25 reinforcing bars with varying lap splice lengths that were sufficiently short to ensure that a bond failure would precede a failure in flexure. Modifications to the bar size factors included in both codes were derived from the resulting test data. The evaluation of the test data shows that decreases to lap splice lengths could be considered for walls subjected to out-of-plane loads, which would facilitate construction.

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.

scholarly journals Study on the Bending and Joint Performances of Reinforced Concrete Beams Using High-Strength Rebars

2021 ◽  
Vol 13 (6) ◽  
pp. 3482
Author(s):  
Seoungho Cho ◽  
Myungkwan Lim ◽  
Changhee Lee
Keyword(s):  
Yield Strength ◽  
High Strength ◽  
Reinforced Concrete Beams ◽  
High Yield ◽  
Performance Tests ◽  
Reinforcing Bars ◽  
Joint Performance ◽  
Lap Splice ◽  
Reinforcing Bar ◽  
Nominal Strength

High-strength reinforcing bars have high yield strengths. It is possible to reduce the number of reinforcing bars placed in a building. Accordingly, as the amount of reinforcement decreases, the spacing of reinforcing bars increases, workability improves, and the construction period shortens. To evaluate the structural performance of high-strength reinforcing bars and the joint performance of high-strength threaded reinforcing bars, flexural performance tests were performed in this study on 12 beam members with the compressive strength of concrete, the yield strength of the tensile reinforcing bars, and the tensile reinforcing bar ratio as variables. The yield strengths of the tensile reinforcement and joint methods were used as variables, and joint performance tests were performed for six beam members. Based on this study, the foundation for using high-strength reinforcing bars with a design standard yield strength equal to 600 MPa was established. Accordingly, mechanical joints of high-strength threaded reinforcing bars (600 and 670 MPa) can be used. All six specimens were destroyed under more than the expected nominal strength. Lap splice caused brittle fractures because it was not reinforced in stirrup. Increases of 21% to 47% in the loads of specimens using a coupler and a lock nut were observed. Shape yield represents destruction—a section must ensure sufficient ductility after yielding. Therefore, a coupler and lock nut are effective.

Application of acoustic emission monitoring for assessment of bond performance of corroded reinforced concrete beams

2016 ◽  
Vol 16 (6) ◽  
pp. 732-744 ◽  
Author(s):  
Ahmed A Abouhussien ◽  
Assem AA Hassan
Keyword(s):  
Acoustic Emission ◽  
Reinforced Concrete ◽  
Concrete Beams ◽  
Signal Strength ◽  
Point Load ◽  
Reinforced Concrete Beams ◽  
Bond Failure ◽  
Acoustic Emission Monitoring ◽  
Bond Performance ◽  
Emission Monitoring

This article presents the results of an experimental investigation on the application of acoustic emission monitoring for the evaluation of bond behaviour of deteriorated reinforced concrete beams. Five reinforced concrete beam–anchorage specimens designed to undergo bond failure were exposed to corrosion at one of the anchorage zones by accelerated corrosion. Two additional beams without exposure to corrosion were included as reference specimens. The corroded beams were subjected to four variable periods of corrosion, leading to four levels of steel mass loss (5%, 10%, 20% and 30%). After these corrosion periods, all seven beams were tested to assess their bond performance using a four-point load setup. The beams were continuously monitored by attached acoustic emission sensors throughout the four-point load test until bond failure. The analysis of acquired acoustic emission signals from bond testing was performed to detect early stages of bond damage. Further analysis was executed on signal strength of acoustic emission signals, which used cumulative signal strength, historic index ( H( t)) and severity ( Sr) to characterize the bond degradation in all beams. This analysis allowed early identification of three stages of damage, namely, first crack, initial slip and anchorage cracking, before their visual observation, irrespective of corrosion level or sensor location. Higher corrosion levels yielded significant reduction in both bond strength and corresponding acoustic emission parameters. The results of acoustic emission parameters ( H( t) and Sr) enabled the development of a damage classification chart to identify different stages of bond deterioration.

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