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.

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 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.

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.

scholarly journals The Mechanical Properties of Steel-Polypropylene Fibre Composites Concrete (HyFRCC)

2015 ◽  
Vol 773-774 ◽  
pp. 949-953 ◽  
Author(s):  
Izni Syahrizal Ibrahim ◽  
Wan Amizah Wan Jusoh ◽  
Abdul Rahman Mohd Sam ◽  
Nur Ain Mustapa ◽  
Sk Muiz Sk Abdul Razak
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Flexural Strength ◽  
Volume Fraction ◽  
Concrete Strength ◽  
Fibre Volume Fraction ◽  
Fibre Volume ◽  
Polypropylene Fibre ◽  
Experimental Results

This paper discusses the experimental results on the mechanical properties of hybrid fibre reinforced composite concrete (HyFRCC) containing different proportions of steel fibre (SF) and polypropylene fibre (PPF). The mechanical properties include compressive strength, tensile strength, and flexural strength. SF is known to enhance the flexural and tensile strengths, and at the same time is able to resist the formation of macro cracking. Meanwhile, PPF contributes to the tensile strain capacity and compressive strength, and also delay the formation of micro cracks. Hooked-end deformed type SF fibre with 60 mm length and fibrillated virgin type PPF fibre with 19 mm length are used in this study. Meanwhile, the concrete strength is maintained for grade C30. The percentage proportion of SF-PPF fibres are varied in the range of 100-0%, 75-25%, 50-50%, 25-75% and 0-100% of which the total fibre volume fraction (Vf) is fixed at 0.5%. The experimental results reveal that the percentage proportion of SF-PPF fibres with 75-25% produced the maximum performance of flexural strength, tensile strength and flexural toughness. Meanwhile, the percentage proportion of SF-PPF fibres with 100-0% contributes to the improvement of the compressive strength compared to that of plain concrete.

Study on the Lead-Free Easy-Cutting Mg-Sb Brass

2011 ◽  
Vol 239-242 ◽  
pp. 1670-1673 ◽  
Author(s):  
Lei Li ◽  
Biao Ma ◽  
Qiang Li ◽  
Guo Jie Huang
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Grain Boundaries ◽  
Human Health ◽  
Hot Working ◽  
Experimental Results ◽  
Lead Free ◽  
Environment Friendly ◽  
Working Property ◽  
Pipe Joint

Traditional lead brass is gradually prevented from application by many countries’ governments because lead does harm to human health and pollutes the environment. New types of environment-friendly lead-free brass with favorable machinability are urgently demanded in the electrical, electronics and plumping fields. Lead-free Mg-Sb brass was fabricated in present. Experimental results showed that when the content of Mg is 1.0wt%, Sb is 0.8wt% and Cu is 58.0~59.0wt%, the alloy’s mechanical properties and machinability are favorable for industry application. With the increase of the content of Sb, the machinability increased, while the mechanical properties decreased. Lots of Cu2Mg and Cu9Sb2 particles on the order of microns exist in the inner-grain and grain boundaries. These particles improve the machinability, however, lower the tensile strength and the elongation. A three-way pipe joint was successfully punched with the fabricated Mg-Sb brass bar, and this demonstrated that the fabricated Mg-Sb brass possesses favorable hot working property.

Modeling and experimental investigation of out-of-plane deformation on mechanical performance of composites manufactured by ATL

2016 ◽  
Vol 36 (5) ◽  
pp. 347-359 ◽  
Author(s):  
Qiyi Chu ◽  
Yong Li ◽  
Jun Xiao ◽  
Dajun Huan ◽  
Xiaodong Chen
Keyword(s):  
Tensile Strength ◽  
Deformation Rate ◽  
Mechanical Performance ◽  
Plane Deformation ◽  
Experimental Results ◽  
Predicting Model ◽  
Fiber Waviness ◽  
Manufacturing Method ◽  
Four Point Bending ◽  
Out Of Plane

The change of mold normal curvature along the trajectory may result in out-of-plane waviness during the automated laying process, on which the layup speed and temperature would have an effect. A new parameter, deformation rate, was defined by combining the effect of mold curvature change rate and layup speed. A predicting model was proposed based on the fiber waviness and interlaminar sliding model to calculate the relationship between stiffness retention and the layup process parameters, including deformation rate and temperature. An experimental study on the effect of different deformation parameters on the tensile performance of composites was carried out based on a new manufacturing method of plated specimens with different levels of waviness by means of a four-point bending fixture. The experimental results showed that when the deformation temperature increases from 20℃ to 80℃, the tensile strength increases first and then decreases while the tensile module keeps increasing. While the deformation rate decreases from 0.40 to 0.04 mm−1/s, both tensile strength and module showed an increasing trend. The predicting model being validated by experimental results can be utilized to optimize the layup process parameter to satisfy the quality and efficiency requirements.

The Effect of Suture Materials on the Biomechanical Performance of Different Flexor Tendon Repairs and the Concept of Construct Efficiency

2018 ◽  
Vol 23 (02) ◽  
pp. 243-247
Author(s):  
Yoke Rung Wong ◽  
Austin Mun Kitt Loke ◽  
Shian Chao Tay
Keyword(s):  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Tensile Testing ◽  
Flexor Tendon ◽  
Experimental Results ◽  
Suture Materials ◽  
Nylon Suture ◽  
Biomechanical Strength ◽  
Repair Techniques

Background: To propose a new term (‘construct efficiency’) for the evaluation of multi strands flexor tendon repairs using different suture materials. Methods: A total of twenty specimens from 4-0 braided polyblend sutures (FiberLoop/FiberWire; Arthrex, Naples, FL) and 4-0 nylon sutures (Supramid Extra II; S. Jackson, Inc., Alexandria, VA) were subjected to tensile testing using Pneumatic Cord-and-Yarn Grips (Instron Corp., Canton MA, USA). The ultimate tensile strengths of the suture materials were measured. The expected repair strengths and construct efficiencies were computed based on the experimental results and from available literature on actual repair strengths of the 4-strand Becker, Cruciate repairs and 6-strand Tang, modified Lim-Tsai repairs. Results: The ultimate tensile strength of nylon suture was 15.4 ± 0.6N, lower than that of braided polyblend suture (45.3 ± 2.3N) with a difference of 194%. The construct efficiency of multi strand repairs varied with respect to different repair techniques and suture materials. It was found that the Becker repairs using FiberWire had the highest construct efficiency (55.7%) followed by the modified Lim-Tsai using Supramid (50.9%), Tang repair using Supramid (49.8%), Cruciate repair using Fiberwire (49.1%), and modified Lim-Tsai repair using FiberLoop (33.5%). Conclusions: The construct efficiency is more accurate in showing that, in terms of biomechanical strength, the use of FiberWire for the 4-strand Becker and Cruciate repair is more efficient than that of using FiberLoop for 6-strand modified Lim-Tsai repair.

Eco-Friendly Composites Based on Bitter Tea Oil Meal and Polylactic Acid

2021 ◽  
Vol 889 ◽  
pp. 21-26
Author(s):  
Yeng Fong Shih ◽  
Jia Yi Xu ◽  
Nian Yi Wu ◽  
Yu Ting Chiu ◽  
Hui Ming Yu ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Maleic Anhydride ◽  
Impact Strength ◽  
Polylactic Acid ◽  
Food Industry ◽  
Impact Resistance ◽  
Experimental Results ◽  
Polybutylene Succinate ◽  
The Cost

Bitter tea oil meal (BTOM) is the main waste from the production of bitter tea oil which is squeezed from bitter tea seeds. The purpose of this study is to reuse the BTOM as an additive of the polylactic acid (PLA) to prepare eco-friendly composites. The effects of the addition of BTOM and maleic anhydride grafted polybutylene succinate (MAPBS) on the properties of PLA were investigated. The addition of MAPBS is mainly to increase the toughness of the PLA, and to increase the compatibility between BTOM and PLA. The experimental results show that the compatibility of PLA and BTOM and impact resistance of the composites can be improved by addition of MAPBS. The composite with 5% BTOM and 8% MAPBS exhibited the best tensile strength. In addition, the composite with 5% BTOM and 5% MAPBS has the best impact strength. It was found that the addition of BTOM and MAPBS can promote the crystallization of PLA. Moreover, the addition of BTOM not only can reduce the usage of PLA and the cost of the materials, but also reuse and reduce the waste from food industry.

Improving the predictions of ASM2d through modelling in practice

2002 ◽  
Vol 45 (6) ◽  
pp. 199-208 ◽  
Author(s):  
L. Larrea ◽  
I. Irizar ◽  
M.E. Hildago
Keyword(s):  
Phosphorus Uptake ◽  
Pilot Scale ◽  
Phosphorus Release ◽  
Reduction Factor ◽  
Experimental Results ◽  
High Rate ◽  
Predictive Capacity ◽  
Kinetic Coefficients ◽  
Autotrophic Biomass ◽  
Rate Processes

The paper presents the adjustments carried out on the structure and in some default values of the kinetic coefficients of the ASM2d model in order to get an improved prediction for the experimental results obtained in pilot scale plants studies with different activated sludge treatment processes for carbon, nitrogen and phosphorous removal. In order to predict the high effluent filtered COD experimentally observed in high rate processes for carbon removal, a new model structure has been proposed, incorporating into the carbon model a soluble fraction of the slowly biodegradable substrate. Studies with the step feed and the alternating processes showed simultaneous nitrification-denitrification in aerated reactors which was predicted with increased values in the oxygen saturation coefficients for heterotrophic and autotrophic biomass. Both processes also showed loss of the denitrification capacity under unfavourable conditions, such us rains and low anoxic fraction, which required a very large decrease in the value of the reduction factor for denitrification so as to improve the predictions for effluent nitrate experimental results. Regarding phosphorus removal, the ASM2d model showed a satisfactory predictive capacity. For improved predictions of phosphorus release in anaerobic conditions, high values of the rate constant for storage of XPHA and low values of the anaerobic hydrolysis reduction factor were used. For phosphorus uptake in aerobic and anoxic conditions satisfactory predictions were obtained using the default values.

Development of Splice Connections for Precast Concrete Structures

2014 ◽  
Vol 980 ◽  
pp. 132-136 ◽  
Author(s):  
Ahmad Baharuddin Abd Rahman ◽  
Jen Hua Ling ◽  
Zuhairi Abd Hamid ◽  
Mohd Hanim Osman ◽  
Shahrin Mohammad ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Failure Modes ◽  
Ultimate Load ◽  
Precast Concrete ◽  
Tensile Load ◽  
Test Results ◽  
Steel Bars ◽  
Embedment Length ◽  
Bar Diameter

This paper presents the test results of proposed grouted sleeve connections under increasing tensile load. The objective of this research was to investigate splice connections that could provide tensile strength similar to the full tensile strength of the connected rebars. The parameters varied were splice types, splice length and rebar embedment length. The performance of the splice connection was evaluated based on the load-displacement, ultimate load, displacements and failure modes. The results show that the strength of splice connection depends on the bond strength between sleeve-to-grout and grout-to-rebar; the tensile strength of spliced steel bars and also the tensile strength of sleeve. It is observed that when the grout compressive strength is more than 60N/mm2and bar embedded length is at least 10 bar diameter, the splice connection in BS series is able to provide full tensile strength of the connected rebars.

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