scholarly journals SHEAR PERFORMANCE OF SPECIAL DRY JOINTS FOR PRECAST CONCRETE SEGMENTS

2021 ◽  
Vol 11 (1) ◽  
pp. 60-72
Author(s):  
Watanachai Smittakorn ◽  
Tosporn Prasertsri ◽  
Worapon Pattharakorn ◽  
Pitcha Jongvivatsakul
Keyword(s):  
Prestressed Concrete ◽  
Precast Concrete ◽  
High Strength ◽  
Shear Capacity ◽  
Fiber Volume ◽  
Strength Concrete ◽  
Test Parameters ◽  
Ductile Shearing ◽  
Shear Performance ◽  
Normal Strength

The special dry joints for precast prestressed concrete segments are invented in this study toovercome the limitation of conventional dry joints. Eight specimens of special dry joints were madeand subjected to direct shear test. Test parameters comprise concrete compressive strength (normaland high strength concrete) and steel fiber volume added in the special dry joint (0%, 0.5%, and1.0%). Test results revealed that the inclusion of steel fibers remarkably enhanced the shear capacityand ductility index. Failure mode of specimens was changed from shearing off to concrete crackingaround shear key corners, defined as ductile shearing-off failure. Furthermore, the existing equationsfor predicting shear capacity of keyed joints were validated by the experimental results. Amongavailable equations from literatures, the Turmo’s equation yields better prediction of the shearcapacity for the special dry joint made with normal strength concrete.

scholarly journals Effect of Using River Sand on The Strength of Normal and High Strength Concrete

2018 ◽  
Vol 7 (4.20) ◽  
pp. 222 ◽  
Author(s):  
Haitham Al-Thairy
Keyword(s):  
High Strength Concrete ◽  
High Strength ◽  
Partial Replacement ◽  
Fine Aggregate ◽  
River Sand ◽  
Strength Concrete ◽  
Concrete Mixtures ◽  
Test Parameters ◽  
Normal Strength ◽  
Compressive And Flexural Strengths

The shortage and high cost of quarries sand in some regions around the world has motivated engineers and researchers to investigate the possibility and feasibility of using other materials to be used as a fine aggregate in concrete mixtures. The main objective of this research is to experimentally investigate the effect of using river sand as a partial replacement of the ordinary quarries sand on the mechanical properties of normal and high strength concrete. Nine concrete mixtures were prepared and tested in terms of fresh and hardened properties using different replacement ratios of the required proportion of the normal sand. Four replacement ratios were used for normal strength concrete (NSC) which are: 0%, 25%, 50% and 75%, whereas, five replacement ratios were used for high strength concrete (HSC) namely: 0%, 35%, 60% and 90%. For each strength grade, the test parameters of the prepared mixtures included compressive and tensile strength. The experimental test results have revealed that it is possible to obtain a normal and high strength concrete with acceptable compressive and flexural strengths values by using river sand with replacement ratios up to 25% and 35% for NSC and HSC, respectively. When the replacement ratios were increased to more than the aforementioned ratios, the strength of the concrete decreased accordingly.  

scholarly journals Numeric Analysis on Shear Behavior of High-Strength Concrete Single-Keyed Dry Joints with Fixing Imperfections in Precast Concrete Segmental Bridges

Materials ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 2914 ◽  
Author(s):  
Haibo Jiang ◽  
Mingzhu Chen ◽  
Zhijun Sha ◽  
Jie Xiao ◽  
Jiahui Feng
Keyword(s):  
Shear Strength ◽  
High Strength Concrete ◽  
Precast Concrete ◽  
Concrete Strength ◽  
High Strength ◽  
Lower Surface ◽  
Shear Capacity ◽  
Experimental Results ◽  
Strength Concrete ◽  
Segmental Bridges

Fixing imperfections in keyed dry joints between the concrete segments compromise the performance of precast concrete segmental bridges (PCSBs), which needs to consider carefully. In this study, a finite-element model on high-strength concrete single-keyed dry joints in PCSBs was established and validated by experimental results. Parametric studies on fixing imperfections in key, concrete strengths, and confining pressures were carried out based on that model. The numeric results included crack patterns, load–displacements and shear strength. Fixing imperfections—especially at lower surface of keys—reduced shear strength of single-keyed dry joints by the different shear transfer mechanism. Higher confining pressure and concrete strength improved the shear strength, but they mitigated and aggravated the effect of fixing imperfections at lower surface of key on shear strength, respectively. Compared with simulating results, AASHTO standard overestimated the shear capacity of single-keyed dry joints with fixing imperfections at lower surface of key by up to 0.602–22.0%, but greatly underestimated that of the rest. A modified formula with a strength reduction factor was proposed. For six experimental three-keyed dry-joint specimens and 30 numeric single-keyed dry-joint specimens with or without fixing imperfections, the average ratio of code predictions to experimental results was 90.4% and 81.6%, respectively.

scholarly journals Shear performance of single-keyed dry joints between reactive power concrete and high strength concrete in push-off tests

2020 ◽  
Vol 103 (2) ◽  
pp. 003685042092864
Author(s):  
Jiahui Feng ◽  
Weibin Liang ◽  
Haibo Jiang ◽  
Chengwang Huang ◽  
Jingyuan Zhang
Keyword(s):  
Compressive Strength ◽  
High Strength ◽  
Shear Capacity ◽  
Steel Fibers ◽  
Reactive Powder Concrete ◽  
Concrete Compressive Strength ◽  
Strength Concrete ◽  
Shear Key ◽  
Shear Performance ◽  
Reactive Powder

Shear key joints are commonly used in constructions of precast concrete segmental bridges. Most researches focused on shear performance of the dry joints with the identical-strength concrete, leaving a research gap on that of composite joints between different concrete segments. This research aims to investigate shear behavior of shear key joint between reactive powder concrete and high strength concrete. Totally 12 specimens of single-keyed dry joint were tested, with the parameters of concrete compressive strength, steel fibers, and confining stress. The experimental results indicated that shear failure was observed, but crushing phenomenon occasionally occurred in composite joints in testing, which was confirmed by stress distribution from numerical simulation. In terms of shear capacity of composite joint, peak shear loads of reactive powder concrete specimens without steel fibers were enhanced by 10%–12% as increasing of concrete compressive strength, while those with steel fibers achieved 22%–25% enhancement. Nevertheless, a slight reduction of normalized shear strength was obtained because of its lower volume fraction of coarse aggregate. In numerical simulation, as increasing the concrete compressive strength of convex part, peak shear load was enhanced, but the increment rate of peak shear load decreased. Shear design formulae underestimated shear capacity of reactive powder concrete specimens with steel fibers, but the models proposed by Buyukozturk and Rombach gave accurate predictions on those without steel fibers.

A Comparative Investigation on Normal and High Strength Concrete Beams under Torsion

2022 ◽  
Vol 1048 ◽  
pp. 359-365
Author(s):  
Ihtesham Hussain Mohammed ◽  
Ahmed Majid Salim Al Aamri ◽  
Shakila Javed ◽  
Yahya Ubaid Al Shamsi
Keyword(s):  
High Strength Concrete ◽  
Concrete Beams ◽  
High Strength ◽  
Comparative Investigation ◽  
Mineral Admixtures ◽  
Torsional Loading ◽  
Torsional Strength ◽  
Strength Concrete ◽  
Loading Method ◽  
Normal Strength

In this study, an experimental investigation was done to study the behaviour of Normal Strength Concrete (NSC) and High Strength Concrete (HSC) Plain beams under torsion with the concrete mix of M40 and M100. No mineral admixtures are used to obtain the required strength of concrete. Eight NSC beams and eight HSC beams whose width was varying with 75 mm, 100 mm, and 150 mm; depth varying as 75 mm, 100 mm, 150 mm and 200 mm; and span of the beams varying 600 mm, 800 mm and 1200 mm were casted and cured to stud the effect of torsion. The principle aim of this study was to understand the torsional behaviour of the NSC and HSC beams for rotation, cracking, size effect and torsional strength. A standard torsional loading method was used for conducting the testing of beams. The results obtained were compared with different theories and code equations. It was observed that the torsional strength of the beam increases with the increase in strength of concrete. HSC beams have higher torsional strength than the NSC beams which has the same amount of reinforcement.

Bond behavior of high strength concrete under reversed pull-out cyclic loading

2002 ◽  
Vol 29 (2) ◽  
pp. 191-200 ◽  
Author(s):  
M Alavi-Fard ◽  
H Marzouk
Keyword(s):  
Cyclic Loading ◽  
Bond Strength ◽  
High Strength Concrete ◽  
Concrete Strength ◽  
High Strength ◽  
Displacement Curve ◽  
Bond Slip ◽  
Strength Concrete ◽  
Pull Out ◽  
Normal Strength

Structures located in seismic zones require significant ductility. It is necessary to examine the bond slip characteristics of high strength concrete under cyclic loading. The cyclic bond of high strength concrete is investigated under different parameters, including load history, confining reinforcement, bar diameter, concrete strength, and the rate of pull out. The bond strength, cracking, and deformation are highly dependent on the bond slip behavior between the rebar and the concrete under cyclic loading. The results of cyclic testing indicate that an increase in cyclic displacement will lead to more severe bond damage. The slope of the bond stress – displacement curve can describe the influence of the rate of loading on the bond strength in a cyclic test. Specimens with steel confinement sustained a greater number of cycles than the specimens without steel confinement. It has been found that the maximum bond strength increases with an increase in concrete strength. Cyclic loading does not affect the bond strength of high strength concrete as long as the cyclic slip is less than the maximum slip for monotonic loading. The behavior of high strength concrete under a cyclic load is slightly different from that of normal strength concrete.Key words: bond, high strength, cyclic loading, bar spacing, loading rate, failure mechanism.

Tensile basic creep versus compressive basic creep at early ages: comparison between normal strength concrete and a very high strength fibre reinforced concrete

2013 ◽  
Vol 47 (10) ◽  
pp. 1773-1785 ◽  
Author(s):  
Pierre Rossi ◽  
Jean Philippe Charron ◽  
Maléna Bastien-Masse ◽  
Jean-Louis Tailhan ◽  
Fabrice Le Maou ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
High Strength ◽  
Basic Creep ◽  
Fibre Reinforced Concrete ◽  
Normal Strength Concrete ◽  
Strength Concrete ◽  
Normal Strength ◽  
Very High
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