Bond position function between deformed steel bars and early-age cementitious grout

2021 ◽  
pp. 136943322110157
Author(s):  
Gang Peng ◽  
Ditao Niu ◽  
Xiaopeng Hu ◽  
Xiao Wu ◽  
Yong Zhang
Keyword(s):  
Ultimate Load ◽  
Tensile Load ◽  
Stress Transfer ◽  
Bond Stress ◽  
Load Testing ◽  
Anchorage Length ◽  
Steel Bar ◽  
Steel Bars ◽  
Two Parameters ◽  
Cover Thickness

Pullout tests for the deformed steel bars in early-aged cementitious grout by considering the variables of testing ages, cover thicknesses, and diameters of steel bar were conducted, and the local bond stress–slip relationship at different positions of the anchorage length of steel bar was studied. Results indicated that, with the increase of testing age, the load-slip curves exhibited a higher ultimate load and had steeper ascending and descending branches; however, the slippage at the ultimate load exhibited a decreasing trend. Moreover, with the increase of cover thickness and diameter of steel bar, the ultimate load of pullout specimens increased obviously, while the corresponding slips generally had no obvious correlations. According to an analysis of the measured rebar strain, the distributions of the steel stress and bond stress as well as the relative slip along the embedded length were obtained under different external loads. Steel stress transfer and bond stress distribution parameters were introduced to characterize the nonuniformity of the distributions of the steel stress and bond stress along the steel bar, and the effects of the testing age, cover thickness, and diameter of steel bar on these two parameters were analyzed. Results showed that the both of these two parameters increased with the increasing tensile load, testing age, and cover thickness and with the decreasing diameter of steel bar. Thereafter, the local bond stress-slip relationships along the anchorage length and position functions reflecting the variations of these relationships were proposed.

The Analysis of the Reliability and Design for Mechanical Anchorage of HRB500 Steel Bars

2011 ◽  
Vol 94-96 ◽  
pp. 970-974
Author(s):  
Xian Rong ◽  
Peng Cheng Liu ◽  
Xue Li
Keyword(s):  
Concrete Strength ◽  
Concrete Cover ◽  
Statistical Regression ◽  
Analysis Method ◽  
Anchorage Length ◽  
Pull Out ◽  
Steel Bar ◽  
Steel Bars ◽  
Mechanical Anchoring ◽  
Cover Thickness

The factors on mechanical anchoring performance of HRB500 steel bars, such as concrete strength, concrete cover thickness, diameter of steel bar, anchorage length of steel bar and transverse reinforcement ratio, were studied based on pull-out tests of 45 specimens. And the formula of mechanical anchoring bond strength for HRB500 steel bars was concluded by statistical regression analysis method. Through the reliability analysis, the mechanical anchoring length of design value and the table of conversion ratio between mechanical and direct anchoring length of HRB500 steel bars have been proposed. So it could be used as a basis for practical projects. The results indicate that the mechanical anchorage length of HRB500 steel bars can be still designed with the formula proposed in GB 50010-2002 “Code for design of concrete structures”.

scholarly journals Basic Mechanical Properties of Duplex Stainless Steel Bars and Experimental Study of Bonding between Duplex Stainless Steel Bars and Concrete

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2995
Author(s):  
Qingfu Li ◽  
Yunqi Cui ◽  
Jinwei Wang
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
Duplex Stainless Steel ◽  
Concrete Strength ◽  
Concrete Cover ◽  
Bond Stress ◽  
Reinforcing Steel ◽  
Anchorage Length ◽  
Steel Bar ◽  
Steel Bars

In recent years, as a result of the large-scale use of stainless steel bars in production and life, people’s demand for stainless steel bars has increased. However, existing research information on stainless steel bars is scant, especially the lack of research on the mechanical properties of duplex stainless steel bars and the bonding properties of duplex stainless steel bars to concrete. Therefore, this paper selects 177 duplex stainless steel bars with different diameters for room temperature tensile test, and then uses mathematical methods to provide suggestions for the values of their mechanical properties. The test results show that the duplex stainless steel bar has a relatively high tensile strength of 739 MPa, no significant yield phase, and a relatively low modulus of elasticity of 1.43 × 105 MPa. In addition, 33 specimens were designed to study the bonding properties of duplex stainless steel bars to concrete. In this paper, the effects of concrete strength, duplex stainless steel reinforcement diameter, the ratio of concrete cover to reinforcing steel diameter, and relative anchorage length on the bond stress were investigated, and a regression model was established based on the experimental results. The results show that, with the concrete strength concrete strength from C25 to C40, the compressive strength of concrete increased by 56.1%, the bond stress increased by 27%; the relative anchorage length has been increased from 3 to 6, the relative anchorage length has doubled, and the bond stress has increased by 13%; and, the ratio of concrete cover to reinforcing steel diameter increased to a certain range on the bond stress has no significant effect and duplex stainless steel reinforcement diameter has little effect on the bond stress. The ratio of concrete cover to reinforcing steel diameter from 3.3 to 4.5 and the bond stress increased by 24.7%. A ratio of concrete cover to reinforcing steel diameter greater than 4.5 has no significant effect on the bond stress, with the average bond stress value of 20.1 MPa. The duplex stainless steel bar diameter has little effect on the bond stress for the diameters of 12 mm, 16 mm, 25 mm duplex stainless steel bar, and their average bond stress is 19.9 MPa.

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.

Experimental Study on Measuring the Steel Stress via FBG Sensors

2014 ◽  
Vol 548-549 ◽  
pp. 663-667 ◽  
Author(s):  
Hong Wei Lin ◽  
Yu Xi Zhao
Keyword(s):  
Experimental Study ◽  
Bond Stress ◽  
Strain Gauges ◽  
Bond Behavior ◽  
Fbg Sensor ◽  
Pullout Tests ◽  
Steel Bar ◽  
Steel Bars ◽  
Fbg Sensors

Studying the bond stress-slip relationship between concrete and corroded steel bar by cutting the steel bars into two separate parts and attaching electric strain gauges in the slots is no longer suitable. To overcome the disadvantages of electric strain gauges in the measuring the stress of corroded steel bars, this paper introduced a new kind of FBG sensor measuring steel stress. By calibration tests, the proportion coefficient between variation of wavelength and steel strain was confirmed as 0.0012. The bond behavior between concrete and steel bar was also investigated by performing pullout tests on beam end specimens.

Development Length Comparison between Australian Codes and Chinese Code on 500MPa Steel Bars

2014 ◽  
Vol 584-586 ◽  
pp. 889-893
Author(s):  
Jing Wen Su ◽  
Hai Tao Li ◽  
Li Xin Liu ◽  
A.J. Deeks ◽  
Fan Wu ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Test Data ◽  
Test Results ◽  
Development Length ◽  
Anchorage Length ◽  
Steel Bar ◽  
Eurocode 2 ◽  
Steel Bars ◽  
Code Provisions ◽  
Good Agreement

This paper presents development length comparison between Chinese and Australian codes study on HRB500 steel bars in concrete. After introducing the existing code provisions about the anchorage length and experimental investigation of tensile HRB500 steel bars, the calculation approaches in different codes are compared with the test data. Additionally, the development length of tensile HRB500 reinforcement bars in AS3600-2001, Proposed Revision of AS3600, GB50010-2010 and the calculation equation proposed from test results are compared with each other in beams and slabs. It is proved that AS3600-2001 is inconsistent with other standards and the tests results and needs to be revised, while the Proposed Revision of AS3600 provided a good agreement with the test data and brings the code into line with other international codes, particularly Eurocode 2. Moreover, the Proposed Revision of AS3600 is a significant improvement on the method in AS3600-2001. The anchorage length formula in GB50010-2010 can still be used for designing HRB500 steel bar.

Test on Hybrid Connection for Steel Bars in Concrete

2012 ◽  
Vol 166-169 ◽  
pp. 215-218
Author(s):  
Ye Tian ◽  
Peng Feng ◽  
Zheng Hai Zhou ◽  
Lie Ping Ye ◽  
Bao Lin Wan
Keyword(s):  
Mechanical Behavior ◽  
Failure Mechanism ◽  
Ultimate Strength ◽  
Ultimate Load ◽  
Engineering Application ◽  
Labor Cost ◽  
Engineering Practice ◽  
Failure Model ◽  
Steel Bar ◽  
Steel Bars

The steel bar connection is an important and inevitable work in civil engineering. The traditional overlapped connection method usually needs to place the transversal rebars in the overlapped splicing area to restrict the splitting cracks in concrete. The steel usage and labor cost are increased. An improved splice, which is the hybrid connection of welding and overlapping, was developed for mid-diameter bars, which is easy to install and has commendable mechanical behavior. A series of reinforcing rebar splice tests with steel-concrete interaction were conducted. The failure model of hybrid connection and the ultimate strength were acquired. Based on the tests, the failure mechanism of hybrid connections was analyzed. The results show that the ultimate load of the new splice is sufficient for the engineering application and the failure model is reasonable. The hybrid connection could be used in the engineering practice.

A new approach for describing pitting corrosion of steel bars in concrete

2017 ◽  
Vol 64 (6) ◽  
pp. 573-579
Author(s):  
Xinchun Guan ◽  
Lianjuan Miao ◽  
Hui Li ◽  
Jinping Ou
Keyword(s):  
Fractal Dimension ◽  
Pitting Corrosion ◽  
Depth Distribution ◽  
Local Corrosion ◽  
Content Type ◽  
Steel Bar ◽  
Steel Bars ◽  
Two Parameters ◽  
Corrosion Of Steel

Purpose The purpose of this study is to quantitively characterize pitting or local corrosion of steel bars. Characterization of pitting or local corrosion is important for steel bar corrosion research in concrete, which is still an unsolved problem for the reason that the pitting on corroded steel is distributed irregularly, besides the varied pitting depths. To solve this problem in a certain degree, two parameters were collectively used to find the pitting distribution and pitting depth distribution of corroded steel bar surface. Design/methodology/approach Corroded reinforcement bars were subjected to two different corrosive conditions to obtain the profile of the surface of corroded steel bar. The arithmetic mean deviation of the profile, Ra, also a roughness parameter, and the fractal dimension, D, were computed using MATLAB software from the data on corroded steel bar profiles scanned by a profile tester. Statistical analysis was performed to determine the parameters distribution of Ra. Findings Ra and D can assist gravimetric technique in defining the degree of pitting corrosion and make further understanding about the characterization of local or pitting corrosion. Originality/value Two parameters were collectively used to find the pitting distribution and pitting depth distribution of corroded steel bar surface, while many studies only study the fractal dimension of pitting corrosion. And, the relationship between these two parameters is studied when using them to describing the non-uniformity of pitting corrosion degree. Using these two parameters can much better describe the non-uniform degree of pitting corrosion.

scholarly journals Bond–Slip Law Between Steel Bar and Different Cement-Based Materials Considering Anchorage Position Function

2021 ◽  
Vol 8 ◽  
Author(s):  
Jie Xiao ◽  
Xiang Long ◽  
Ming Ye ◽  
Haibo Jiang ◽  
Lingfei Liu ◽  
...  
Keyword(s):  
Limit State ◽  
Critical Limit ◽  
Anchorage Length ◽  
Relative Slip ◽  
Bond Slip ◽  
Bond Performance ◽  
Steel Bar ◽  
Steel Bars ◽  
Cement Based Materials ◽  
Measured Strain

The bond performance between steel bar and cement-based materials was the prerequisite for the two materials to work together, and previous studies showed that the bond behavior of the steel bars and cement-based materials will vary with the kinds of cement-based materials. For this reason, this paper adopted 12 direct pullout test specimens including three types of concrete and two types of steel bars. The strain of the steel bar at six measuring points was measured with a strain gauge. Based on the measured strain and free end slip of the steel bars, the distribution of steel stress, bond stress, and relative slip and the bond slip relation along the anchorage length were obtained and analyzed for different concrete and different steel bars. Based on these test results of steel strain and relative slip at six measuring points, the anchorage position function could be established in consideration of anchorage position, which was conducive to the establishment of an accurate bond–slip relationship. In addition, the anchorage length of the steel bar in Engineered Cementitious Composites (ECC) calculated from the equilibrium equation of critical limit state is only half of the anchorage length calculated in the current Code for Design of Concrete Structures (GB 50010-2010) in China. It is suggested to establish the critical anchorage length formula suitable for ECC in future studies.

scholarly journals Application of artificial neural networks and multiple linear regression on local bond stress equation of UHPC and reinforcing steel bars

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ahad Amini Pishro ◽  
Shiquan Zhang ◽  
Dengshi Huang ◽  
Feng Xiong ◽  
WeiYu Li ◽  
...  
Keyword(s):  
Linear Regression ◽  
Multiple Linear Regression ◽  
High Performance ◽  
High Performance Concrete ◽  
Bond Stress ◽  
Ultra High Performance Concrete ◽  
Steel Bar ◽  
Steel Bars ◽  
Artificial Neural ◽  
Artificial Neural Network Ann

AbstractWe investigated the use of an Artificial Neural Network (ANN) to predict the Local Bond Stress (LBS) between Ultra-High-Performance Concrete (UHPC) and steel bars, in order to evaluate the accuracy of our LBS equation, proposed by Multiple Linear Regression (MLR). The experimental and numerical LBS results of specimens, based on RILEM standards and using pullout tests, were assessed by the ANN algorithm using the TensorFlow platform. For each specimen, steel bar diameters ($$d_{b} )$$ d b ) of 12, 14, 16, 18, and 20, concrete compressive strength ($$f_{c}^{\prime }$$ f c ′ ), bond lengths ($$L$$ L ), and concrete covers ($$C$$ C ) of $$d_{b}$$ d b , $$2d_{b}$$ 2 d b , $$3d_{b}$$ 3 d b and $$4d_{b}$$ 4 d b were used as input parameters for our ANN. To obtain an accurate LBS equation, we first modified the existing formula, then used MLR to establish a new LBS equation. Finally, we applied ANN to verify our new proposed equation. The numerical pullout test values from ABAQUS and experimental results from our laboratory were compared with the proposed LBS equation and ANN algorithm results. The results confirmed that our LBS equation is logically accurate and that there is a strong agreement between the experimental, numerical, theoretical, and the predicted LBS values. Moreover, the ANN algorithm proved the precision of our proposed LBS equation.

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