scholarly journals Investigation of Strain of Steel Reinforcement of Modular Flexural Member at Discontinuity Interface

2019 ◽  
Vol 9 (22) ◽  
pp. 4922
Author(s):  
Park ◽  
Lee ◽  
Park ◽  
Choi ◽  
Hong
Keyword(s):  
Crack Width ◽  
Tensile Load ◽  
Tensile Behavior ◽  
Steel Reinforcement ◽  
Modular Structure ◽  
Structural Behavior ◽  
Flexural Member ◽  
Maximum Crack ◽  
Increasing Load

The modular structure has a discontinuity owing to the joint between the modules; thus, structural behavior verification is required. In this study, the tensile behavior of a steel reinforcement at the discontinuity interface was evaluated in the joint of a modular flexural member. The modular specimen was fabricated with a 400 mm joint, and an integral specimen was fabricated with the same specifications as the modular specimen, without a joint. The largest crack width of the integral specimen was measured at the center of the beam, and that of the modular specimen was measured at the discontinuity interface. The maximum crack width of the modular specimen was greater than that of the integral specimen. The strain of the steel reinforcement was estimated using the measured crack width and six formulas for evaluating the crack width. The estimated strain of the modular specimen was higher than that of the integral specimen, and the deformation of the steel reinforcement at the discontinuity interface was accelerated with the increasing load. Therefore, the tensile load was concentrated at the discontinuity interface in the modular specimen, and the steel reinforcement at the discontinuity interface was likely to yield earlier than the integral specimen.

Simplied Calculation Method for Reinforcement of Rectangular Sectional Flexural Members Considering Crack Width

2011 ◽  
Vol 295-297 ◽  
pp. 618-621
Author(s):  
Jian Yuan ◽  
Min Chen
Keyword(s):  
Calculation Method ◽  
Crack Width ◽  
Rectangular Section ◽  
Flexural Members ◽  
Steel Bars ◽  
Calculation Process ◽  
Flexural Member ◽  
Reinforcement Parameter ◽  
Maximum Crack ◽  
Distributed Strain

Based on maximum crack width checking of flexural member with rectangular section, the limited maximum crack width value of code was substituted into checking formula. In this paper, according to the different value scope of non-uniformly distributed strain of coefficient longitudinal tensile reinforcement, controlling equations expressed with the diameter and numbers of steel bars are derived, thus reinforcement meeting the requirement of crack width can be calculated directly according to known value. The example indicates that this method can avoid the repeated reinforcement adjustment and crack checking calculation process, and the reinforcement parameter can meet the requirements well. It may be a reference for the designers.

scholarly journals Self-Healing Biogeopolymers Using Biochar-Immobilized Spores of Pure- and Co-Cultures of Bacteria

2020 ◽  
Author(s):  
Jadin Zam S. Doctolero ◽  
Arnel B. Beltran ◽  
Marigold O. Uba ◽  
April Anne S. Tigue ◽  
Michael Angelo B. Promentilla
Keyword(s):  
Image Analysis ◽  
Crack Width ◽  
Ultrasonic Pulse ◽  
Self Healing ◽  
Weak Effect ◽  
Bacterial Cultures ◽  
Healing Agent ◽  
Optimum Response ◽  
Maximum Crack ◽  
Cultured Bacteria

A sustainable solution for crack maintenance in geopolymers is necessary if they are to be the future of modern green construction. This study thus aimed to develop self-healing biogeopolymers that could potentially rival bioconcrete. First, a suitable healing agent was selected from Bacillus subtilis, B. sphaericus, and B. megaterium by directly adding their spores in the geopolymers and subsequently exposing them to a large amount of nutrients for 14 days. SEM-EDX analysis revealed the formation of biominerals for B. subtilis and B. sphaericus. Next, the effect of biochar-immobilization and co-culturing (B. sphaericus and B. thuringiensis) on the healing efficiencies of the geopolymers were tested and optimized by measuring their ultrasonic pulse velocities weekly over a 28-day healing period. The results show that using co-cultured bacteria significantly improved the observed efficiencies, while biochar-immobilization had a weak effect but yielded an optimum response between 0.3-0.4 g/mL. The maximum crack width sealed was 0.65 mm. Through SEM-EDX and FTIR analyses, the biominerals precipitated in the cracks were identified to be mainly CaCO3. Furthermore, image analysis of the XCT scans of some of the healed geopolymers confirmed that their pulse velocities were indeed improving due to the filling of their internal spaces with biominerals. With that, there is potential in developing self-healing biogeopolymers using biochar-immobilized spores of bacterial cultures.

Research on Influences of the Coarse Aggregate Size on the Cracks of the Reinforced Beam

2012 ◽  
Vol 503-504 ◽  
pp. 832-836
Author(s):  
Hong Quan Sun ◽  
Jun Ding
Keyword(s):  
Reinforced Concrete ◽  
Crack Width ◽  
Coarse Aggregate ◽  
Concrete Beams ◽  
Fractal Theory ◽  
Aggregate Size ◽  
Reinforced Concrete Beams ◽  
Static Loads ◽  
Reinforced Beams ◽  
Maximum Crack

This paper gives the influences of the coarse aggregate size on the cracks of the beam with different aggregate sizes under static loads. The coarse aggregate sizes are ranked into three classes: small size (4.75mm ~ 19mm), big size (19mm ~ 37.5mm) and mixed size (4.75mm ~ 37.5mm). The developments of cracks of three reinforced concrete beams with the different of coarse aggregate sizes under the static loads are researched. The results show that under the action of the same loads, The reinforced concrete beams with the big aggregate size and mixed aggregate size have almost the same maximum crack width, while the maximum crack width of the beam with small aggregate size is less than formers. Using fractal theory, the fractal dimension of the cracks is studied. The result shows that the aggregate sizes have significant effect to the cracks on the reinforced beams.

scholarly journals Experiment and Simulation Investigation on the Tensile Behavior of Composite Laminate with Stitching Reinforcement

2011 ◽  
Vol 2011 ◽  
pp. 1-10
Author(s):  
Yi Wang ◽  
Nai Xian Hou ◽  
Zhu Feng Yue
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Significant Influence ◽  
Composite Structures ◽  
Composite Laminate ◽  
Tensile Load ◽  
Tensile Behavior ◽  
The Finite Element Method ◽  
Tensile Process ◽  
Simulation Results

The experiments and finite element simulations of composite laminate with stitching are carried out. Firstly, the monotonous tensile experiments with and without stitching are conducted to investigate the influence of stitch reinforcement on the composite laminate. Secondly, the finite element method (FEM) is employed to simulate the tensile process of specimens, and the link element is introduced to simulate the stitching. The experiment results shows that the stitching has little influence on the damage load under monotonous tensile load, while there is a significant influence on the changing of strain. The FEM results are consistent with the experiment results, which means that the link element can be used to study the stitching of the composite laminate. The simulation results also show that the distributions of strain are changed obviously due to the existence of the stitching. Research results have a significant role on the design of the composite structures with and without stitching.

Study on Mechanical Properties of Corroded Reinforced Concrete Using Support Vector Machines

2014 ◽  
Vol 578-579 ◽  
pp. 1556-1561 ◽  
Author(s):  
Shuai Yang ◽  
Cong Qi Fang ◽  
Zhi Jie Yuan
Keyword(s):  
Mechanical Properties ◽  
Reinforced Concrete ◽  
Support Vector Machines ◽  
Crack Width ◽  
Black Box ◽  
Reduction Factor ◽  
Support Vector ◽  
Regression Formula ◽  
Vector Machines ◽  
Maximum Crack

The mechanical properties of corroded reinforced concrete under repeated load are investigated. The maximum crack width, mid-span deflection and reduction factor are predicted by using support vector machines. The maximum crack width and deflection are predicted by the black-box modeling based on support vector machines with the radial basis function kernel function. The reduction factor is predicted by using piecewise regression formula, whole regression formula and black-box modeling, respectively. The proposed prediction method is verified by comparing all prediction results with the experimental values. It is shown that the proposed method has high prediction accuracy, extensive applicable range and many predictive strategies.

scholarly journals Regression Analysis of Bond Parameters between Corroded Rebar and Concrete Based on Reported Test Data

2018 ◽  
Vol 2018 ◽  
pp. 1-18 ◽  
Author(s):  
H. J. Zhou ◽  
Y. F. Zhou ◽  
Y. N. Xu ◽  
Z. Y. Lin ◽  
F. Xing ◽  
...  
Keyword(s):  
Regression Analysis ◽  
Bond Strength ◽  
Crack Width ◽  
Experimental Tests ◽  
Test Results ◽  
Bond Slip ◽  
Regression Effect ◽  
Pull Out ◽  
Maximum Crack ◽  
Best Fit

Reinforcement corrosion is a major cause of degradation in reinforced concrete structures. The fragile rust layer and cracking and spalling of the cover caused by splitting stress due to rust expansion can alter bond behaviors significantly. Despite extensive experimental tests, no stochastic model has yet incorporated randomness into the bond parameters model. This paper gathered published experimental data on the bond-slip parameters of pull-out specimens and beam-end specimens. Regression analysis was carried out to identify the best fit of bond strength and the corresponding slip value in the context of different corrosion levels from the recollected test results. An F-test confirmed the regression effect to be significant. Residual data were also analyzed and found to be well described by a normal distribution. Crack width data of the tested specimens were also collected. A regression analysis of the bond strength and maximum crack width was carried out given the comparative simplicity of measuring crack width versus rebar area loss. Results indicate that maximum crack width can also be used to predict bond strength degradation with similar variation magnitude.

scholarly journals Restricted Effect of Two Plant Root Systems on the Crack Expansion of China Yunnan Laterite under Dry-wet Cycle

2020 ◽  
pp. 01-10
Author(s):  
Weiwei Zhu, Guojian Feng, Jun Du
Keyword(s):  
Statistical Analysis ◽  
Crack Width ◽  
Plant Root ◽  
Root Systems ◽  
Soil Samples ◽  
Heteropogon Contortus ◽  
Average Maximum ◽  
Maximum Crack ◽  
Plant Root Systems ◽  
Natural Drying

In order to research the restricted effect of hedera nepalensis root systems and heteropogon contortus root systems on the crack expansion of Yunnan laterite under dry-wet cycle, this paper prepares Yunnan laterite with certain moisture content, and makes the compacted samples of pure laterite and composite soil mixed with root systems by adopting hedera nepalensis root systems and heteropogon contortus root systems respectively, and then simulates the dry-wet cycle of laterite in engineering (i.e., rainfalls and evaporations), measures the crack width of samples experiencing different cycles, and makes statistical analysis on the average maximum crack width of samples in all groups by adopting the method of indoor spraying and natural drying. The result indicates that, 10% and 20% mixed hedera nepalensis root systems can exert obvious restrictions on the crack expansion of Yunnan laterite after dry-wet cycle, while 30% mixed hedera nepalensis root systems and 10% mixed heteropogon contortus root systems can also restrict the crack expansion of Yunnan laterite, but the restricted effect is weaker. As for 20% and 30% mixed heteropogon contortus root systems, composite soil samples will disintegrate after the 2nd dry-wet cycle.

scholarly journals CRACK ANALYSIS OF CFRP REINFORCED CONCRETE BEAMS UNDER SECONDARY LOADING

2021 ◽  
Vol 30 (4) ◽  
Author(s):  
Jinliang Liu ◽  
Jiawei Wang ◽  
Yanmin Jia
Keyword(s):  
Reinforced Concrete ◽  
Crack Width ◽  
Concrete Beam ◽  
Reinforced Concrete Beam ◽  
Crack Spacing ◽  
Reinforced Concrete Beams ◽  
Calculation Formula ◽  
Plate Area ◽  
Average Crack ◽  
Maximum Crack

The paper established the calculation formulas on the average crack spacing and the maximum crack width of CFRP（Carbon Fiber Reinforced Polymer）reinforced concrete beam under the secondary loading. Conversion of CFRP plate area into the reinforcement ratio of the reinforced beam, the calculation formula on the average crack spacing of CFRP reinforced concrete beam under the secondary loading was established. On basis of the calculation formula on the maximum crack width of concrete beam, the calculation formula on the maximum crack width of CFRP reinforced concrete beam under the secondary loading was established. The average crack spacing and the maximum crack width calculated by the formulas in the paper were compared with the test data, it was verified that the formula is correct.

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