scholarly journals Bond Strength and Flexural Capacity of Normal Concrete Beams Strengthened with No-Slump High-Strength, High-Ductility Concrete

Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4218 ◽  
Author(s):  
Tian-Feng Yuan ◽  
Se-Hee Hong ◽  
Hyun-Oh Shin ◽  
Young-Soo Yoon
Keyword(s):  
High Strength ◽  
Flexural Behavior ◽  
High Ductility ◽  
Test Results ◽  
Shear Tests ◽  
Concrete Members ◽  
Strength Tests ◽  
High Roughness ◽  
Normal Strength ◽  
Slant Shear

This study investigates the flexural behavior of normal-strength concrete (NSC) beams that were strengthened with no-slump, high-strength, high-ductility concrete (NSHSDC). A set of slant shear tests was performed to investigate the initial performance of the NSC substrate strengthened with NSHSDC. Slant shear tests considered two types of roughness of interface and five angles of the interface between NSC and NSHSDC. The test results showed that except for specimens with a 75° interface angle, the specimens with high roughness were conformed to the properties (14–21 MPa for 28 days) of the ACI Committee 546 recommendation. For flexural strength tests, NSC beams strengthened with an NSHSDC jacket on the top and bottom sides, three sides, and four sides resulted in strength increments of about 8%, 29%, and 40%, respectively, compared to the beams without NSHSDC jacket. Therefore, the use of NSHSDC is an effective method to improve the performance of NSC beams and is recommended for strengthening reinforced concrete members.

scholarly journals Flexure Performance of Externally Bonded CFRP Plates-Strengthened Reinforced Concrete Members

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Xin Yuan ◽  
Chaoyu Zhu ◽  
Wei Zheng ◽  
Jiangbei Hu ◽  
Baijian Tang
Keyword(s):  
Failure Modes ◽  
Calculation Model ◽  
Flexural Behavior ◽  
Test Results ◽  
Flexural Test ◽  
Concrete Members ◽  
Cfrp Plate ◽  
Matlab Program ◽  
Externally Bonded ◽  
The Relationship

This paper investigates the flexural behavior of CFRP plate-strengthened concrete structures. Specimens of the CFRP plate-reinforced beam were designed and tested by the four-point flexural test. The load-deflection relationship, failure modes, and crack propagation were analyzed. The results showed that the postcracking stiffness and bearing capacity of the test beams can be improved by the additional anchoring measures for CFRP strengthening. The relationship between flexural moment and curvature was analyzed by introducing a MATLAB program. The calculation model between curvature, flexural moment, and stiffness was derived for the CFRP plate-strengthened structure. The recommended calculation model was applied in the analysis of deflection, and the theoretical values were compared with the test results.

FRP-Concrete-Steel Double Skin Tubular Cantilever Beams: Behavior under Cyclic Loading

2015 ◽  
Vol 752-753 ◽  
pp. 572-577
Author(s):  
Yunita Idris ◽  
Togay Ozbakkloglu
Keyword(s):  
Experimental Study ◽  
Cyclic Loading ◽  
Lateral Displacement ◽  
High Strength ◽  
Steel Tube ◽  
Flexural Behavior ◽  
Cantilever Beams ◽  
Test Results ◽  
Double Skin ◽  
Reversed Cyclic

This paper reports on an experimental study on the flexural behavior of fiber reinforced polymer (FRP)-concrete-steel double skin cantilever beams (referred to as DSTBs) that were tested under reversed cyclic loading. The beams were manufactured using a high-strength concrete (HSC) mix and they were 150 mm in diameter and 1.2 m in length. The main parameters of the experimental study included the size of the inner steel tube and the use of mechanical connectors in the form of steel rings welded on the inner steel tube. Test results indicate that DSTBs are capable of developing a highly ductile behavior under reversed cyclic lateral displacement excursions. It is found that the addition of mechanical connectors on the steel tube has no significant influence on the lateral displacement capacity of the test specimens, but they can eliminate the slippage between the concrete and inner steel tube. Examination of the test results has led to a number of significant conclusions on the influence of the beam parameters on the performance of DSTBs, which are discussed in the paper.

Seismic behavior of normal-strength concrete-filled precast high-strength concrete centrifugal tube columns

2019 ◽  
Vol 23 (4) ◽  
pp. 614-629
Author(s):  
Shaohua Zhang ◽  
Xizhi Zhang ◽  
Shengbo Xu ◽  
Xingqian Li
Keyword(s):  
Axial Compression ◽  
High Strength Concrete ◽  
Seismic Behavior ◽  
Failure Modes ◽  
Concrete Strength ◽  
High Strength ◽  
Test Results ◽  
Normal Strength Concrete ◽  
Strength Concrete ◽  
Normal Strength

This study reports the cyclic loading test results of normal-strength concrete-filled precast high-strength concrete centrifugal tube columns. Seven half-scale column specimens were tested under cyclic loads and axial compression loads to investigate their seismic behavior. The major parameters considered in the test included axial compression ratio, filled concrete strength, and volumetric stirrup ratio. The structural behavior of each specimen was investigated in terms of failure modes, hysteresis behavior, bearing capacity, dissipated energy, ductility, stiffness degradation, drift capacity, and strain profiles. Test results revealed that the concrete-filled precast high-strength concrete centrifugal tube column exhibited good integral behavior, and the failure modes of all columns were ductile flexural failures. Lower axial compression ratio and higher volumetric stirrup ratio resulted in more satisfactory ductile performance. In contrast, the filled concrete strength has a limited influence on the structural behavior of concrete-filled precast high-strength concrete centrifugal tube columns. Based on the limit analysis method, the calculation formula for the bending capacity of the concrete-filled precast high-strength concrete centrifugal tube column was developed, and the results predicted from the formulas were in good agreement with the experiment results.

scholarly journals EXPERIMENTAL LOAD-DRIFT RELATIONS OF CONCRETE BEAM REINFORCED AND CONFINED WITH HIGH-STRENGTH STEEL BARS UNDER REVERSED CYCLIC LOADING

2021 ◽  
Vol 11 (4) ◽  
pp. 56-69
Author(s):  
Retno Anggraini ◽  
Tavio Tavio ◽  
Gusti Putu Raka ◽  
Agustiar Agustiar
Keyword(s):  
Reinforced Concrete ◽  
High Strength Steel ◽  
Concrete Beam ◽  
Concrete Beams ◽  
Concrete Strength ◽  
High Strength ◽  
Reinforced Concrete Beams ◽  
Test Results ◽  
Steel Bars ◽  
Normal Strength

High-strength steel bars have different characteristics from normal-strength steel bars. Thus, the use of high-strength steel bars still needs to be investigated further before it can be used confidently in concrete structures. In the design, a reinforced concrete beam should also have enough ductility besides its loading capacity. One of the indicators identifies that a structure has sufficient ductility is its ability to maintain the load steadily due to progressive deformation. This paper presents the test results of three reinforced concrete beams designed with concrete strength (fc) of 30 MPa. Two different yield strengths (fy) of longitudinal and transverse reinforcements were used, namely, 420 and 550 MPa. The cross-sectional dimensions of the beams were 200  300 mm with a total span of 2000 mm and a rigid stub at the midspan. The beams were simply supported by double rollers at their tops and bottoms. These special supports were located at both ends of the beams. The load applied at the midspan of the beam through the rigid stub with the displacement control. The loading pattern protocol by the drift was set from 0 to 5.5 percent. Based on the test results, it can be seen that the beams with high-strength steel bars could achieve a higher load capacity than the beams with normal-strength steel bars. On the other hand, the beams with high-strength steel bars produced lower deflection than the beams with normal-strength steel bars. Furthermore, it can be concluded that all the beams could withstand the minimum required of 3.5 percent. None of the beams indicated brittle failures. All of the beams could survived until the end of the cycles at a drift of 5.5 percent. This condition indicates that the reinforced concrete beams with higher-strength reinforcement (fy of 550 MPa) could also maintain their load capacities under large deformation beyond the first yielding of the longitudinal steel bars.

BOND STRENGTH RECOVERY OF FIRE-DAMAGED CONCRETE AFTER POST-FIRE-CURING

2015 ◽  
Vol 2 (1) ◽  
Author(s):  
Zhuguo Li ◽  
Yasuhiro Ryuda
Keyword(s):  
Bond Strength ◽  
High Strength ◽  
Test Results ◽  
Strength Concrete ◽  
Pull Out ◽  
Strength Recovery ◽  
Steel Bars ◽  
Bond Strengths ◽  
Normal Strength ◽  
Curing Age

The effects of post-fire-curing on the bond strength recovery of fire-damaged concrete were investigated in this study. Normal strength concrete (NSC) and high-strength concrete (HSC) specimens with deformed steel bars were prepared respectively. We measured the bond strength of unheated NSC and HSC, and exposed other NSC and HSC specimens to high temperatures of 300℃, 400℃, and 500℃, respectively for 120 minutes. Following by rapid cooling with water, the bond strengths of heated NSC and HSC were measured instantly without re-curing, the remains were cured in water for 28 days, or further in the air of 20℃, 60% R.H. for 56 ~62 days. After the re-curing, the pull-out tests were conducted. The test results indicate that the post-fire-curing contributes to a substantial bond strength recovery of heated concrete. The longer the re-curing in water, the greater the recovery extent. At 90 days of re-curing age, the bond strength rose up to around 77% for NSC, and around 70% for HSC, respectively.

Steel and Steel-Concrete Composite Columns of HEA-Cross-Sections with Member Imperfections, Subjected to Buckling Compression

2013 ◽  
Vol 743 ◽  
pp. 164-169
Author(s):  
Marcela Karmazínová
Keyword(s):  
Cross Sections ◽  
Initial Imperfection ◽  
High Strength ◽  
Load Carrying Capacity ◽  
Test Results ◽  
Composite Columns ◽  
Geometrical Imperfection ◽  
Load Carrying ◽  
Buckling Resistance ◽  
Normal Strength

The paper deals with the problems of the load-carrying capacity of steel and steel-concrete composite members composed of high-strength materials, subjected to compression. The attention is mainly paid to the buckling resistance in the connection with member imperfections, which are usually covered by the equivalent initial geometrical imperfection expressed as the maximal initial member curving in the mid-length of the buckled member subjected to compression. The paper is oriented to the analytical solution of the initial eccentricity based on the conception of the buckling strength and to the possibilities how to verify the initial imperfection experimentally. The analysis of this problem is shown on the examples of steel and steel-concrete composite columns represented by open HEA cross-section and by the same cross-sections partially encased by normal-strength and high-strength concrete. Using test results of the specimens subjected to compression the comparison of actual values of initial imperfections with the corresponding theoretical values is presented here.

scholarly journals Torsional behaviour of normal strength RCC beams with ferrocement “U” wraps

2018 ◽  
Vol 16 (1) ◽  
pp. 1-16
Author(s):  
Gopal Behera ◽  
Manoranjan Dhal
Keyword(s):  
Fiber Reinforced Polymers ◽  
Test Results ◽  
Fiber Reinforced ◽  
Carbon Fiber Reinforced Polymers ◽  
Reinforced Polymers ◽  
Concrete Members ◽  
Glass Fiber Reinforced ◽  
Torsional Loads ◽  
Normal Strength ◽  
Concrete Elements

Wrapping technology is one of the effective ways of strengthening concrete elements. Several researchers reported the effectiveness of Glass fiber reinforced polymers and carbon fiber reinforced polymers for improving the strength of the concrete elements. Wrapping on three sides is one of the effective methods for strengthening the beams supporting slabs. Scant literature is available on the strength enhancement of ?U? wrapped concrete elements subjected to torsional loads. In this investigation an attempt is made to quantify the improvement in the behaviour of ?U? wrapped rectangular concrete members subjected to torsional loads ?U? wraps. Ferrocement is taken here as wrapping material. Beams were cast with different number of mesh layers with different torsional reinforcement. The beams were analyzed with MARS. The predictions are in good agreement with experimental test results.

scholarly journals Effect of Aggregate Size on Strength Characteristics of High Strength Lightweight Concrete

Materials ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1314
Author(s):  
Hui Wei ◽  
Yang Liu ◽  
Tao Wu ◽  
Xi Liu
Keyword(s):  
Compressive Strength ◽  
Lightweight Concrete ◽  
Aggregate Size ◽  
Lightweight Aggregate ◽  
High Strength ◽  
Medium Size ◽  
Test Results ◽  
Estimation Model ◽  
Strength Tests ◽  
Single Size

Effects of aggregate size on the mechanical properties of lightweight concrete (LC) were investigated. Four gradings of lightweight aggregate (LWA) were designed and used to prepare the specimens for compressive strength, splitting tensile strength, and flexural strength tests. An estimating method for compressive strength of LC was then established. The compressive strength of tested LC was up to 95 MPa at 90-day curing time. The test results suggested that the absence of medium-size particles decreased the compaction of LC, therefore the density and compressive strength were negatively affected. Specimens having single size of aggregate showed lower splitting tensile and flexural strengths than that having three sizes of LWA. The parameters of the estimating model were determined according to the test results, and the compressive strength predictions of estimation model were compared with the results from other literature.

scholarly journals CRACKING SHEAR STRENGTH OF RC SLENDER BEAMS WITHOUT STIRRUPS/SANKABOMIS NEARMUOTŲ LIAUNŲ GELŽBETONINIŲ SIJŲ ATSPARUMAS SKERSINEI JĖGAI

2008 ◽  
Vol 14 (3) ◽  
pp. 177-182 ◽  
Author(s):  
Guray Arslan
Keyword(s):  
Shear Strength ◽  
Test Data ◽  
High Strength Concrete ◽  
High Strength ◽  
Test Methods ◽  
Test Results ◽  
Strength Concrete ◽  
Concrete Members ◽  
Wide Range ◽  
Slender Beams

This study presents alternative cracking shear strength equations for slender reinforced concrete (RC) beams without stirrups. More than 80 data has been obtained from existing sources of RC beam shear test results covering a wide range of beam properties and test methods. The proposed cracking shear strength equations are applied to existing test data for normal strength concrete (NSC) and high‐strength concrete (HSC) slender beams and the results are compared with those predicted by the ACI 318 equations. It can be also noted that the test results are in better agreement with proposed cracking shear strengths. However, because the test data for high‐strength concrete members are very limited, further research is required to verify these equations. Santrauka Pateikta alternatyvi sankabomis nearmuotų liaunų gelžbetoninių sijų pleišėjimo stiprio įstrižajame pjūvyje skaičiavimo formulė. Surinkta daugiau nei 80 gelžbetoninių sijų eksperimentinių duomenų, kurie apima platų geometrinių matmenų, medžiagų savybių ir bandymo metodų spektrą. Šiai duomenų imčiai atliktas lyginamasis statistinis pleišėjimo stiprio įstrižajame pjūvyje skaičiavimas taikant pasiūlytąją formulę bei ACI 318 projektavimo normų priklausomybę. Derėtų pabrėžti, kad pasiūlyta išraiška gautas geresnis teorinių ir eksperimentinių skaičiavimo rezultatų sutapimas. Vis dėlto aukšto stiprio betono sijų eksperimentinių duomenų kiekis yra ribotas. Todėl pasiūlyta priklausomybė turėtų būti tobulinama, tiksliau įvertinama betono stiprio įtaka.

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