• Proceedings of the Korea Concrete Institute Conference
• /
• 1995.04a
• /
• pp.325-330
• /
• 1995

Three types of model concrete with different mix ratios for 1/10 scale reinforced concrete model were made and tested to find the best solution for the simulation of mechanical characteristics of prototype concrete. Scaled reinforcing materials in diameter(D1.8) having similar con-figuration and mechanical properties with commercial deformed bars(D19) were prepared for 1/10 scale model tests of reinforced concrete structures. Two types of model test using D1.8 model reinforcing bars and model concrete, monotonic simple beam test and cyclic cantilever beam test, were performed to ensure and check the similitude of bond behavior between 1/10 scale model and prototype. The test results showed that the flexural behavior of 1/10 scale models can be simulated with accuracy enough for practical use in monotonic and cyclic loading test.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2005.11a
• /
• pp.93-96
• /
• 2005

Since the columns with flexure-shear failure have lower ductility than those with flexural failure, shear capacity curve models shall be applied as well as flexural capacity curve in order to determine ultimate displacement for seismic design or performance evaluation. In this paper, a modified shear capacity curve model is proposed and compared with the other models such as the CALTRANS model, Aschheim et al.'s model, and Priestley et al.'s model. Four shear capacity curve models are applied to the 4 full scale circular bridge column test results and the accuracy of each model is discussed. It may not be fully adequate to drive a final decision from the application to the limited number of test results, however the proposed model provides the better prediction of failure mode and ultimate displacement than the other models for the selected column test results.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2006.05a
• /
• pp.186-189
• /
• 2006

Since the columns with flexure-shear failure have lower ductility than those with flexural failure, shear capacity curve models shall be applied as well as flexural capacity curve in order to determine ultimate displacement for seismic design or performance evaluation. In this paper, a proposed modified shear capacity curve model is compared with the other models such as the CALTRANS model, Aschheim et al.'s model, and Priestley et al.'s model. Four shear capacity curve models are applied to the 4 full scale and 7 small scale circular bridge column test results and the accuracy of each model is discussed. It may not be fully adequate to drive a final decision from the application to the limited number of test results, however the proposed model provides the better prediction of failure mode and ultimate displacement than the other models for the selected column test results.

• Advances in concrete construction
• /
• v.10 no.1
• /
• pp.81-92
• /
• 2020

Flexural and splitting strength behavior of conventional concrete can significantly be improved by incorporating the fibers in it. A significant number of research studies have been conducted on various types of fibers and their influence on the tensile capacity of concrete. However, as an important property, tensile capacity of fiber reinforced concrete (FRC) is not modelled properly. Therefore, this paper intends to formulate a model based on experiments that show the relationship between the fiber properties such as the aspect ratio (length/diameter), fiber content, compressive strength, flexural strength and splitting strength of FRC. For the purpose of modeling, various FRC mixes only with steel fiber are adopted from the existing research papers. Automated neural network search (ANS) is then developed and used to investigate the effect of input parameters such as fiber content, aspect ratio and compressive strength to the output parameters of flexural and splitting strength of FRC. It is found that the ANS model can be used to predict the flexural and splitting strength of FRC in a sensible precision.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.15 no.5
• /
• pp.3251-3259
• /
• 2014

This paper presents experimental and analytical research results to predict nonlinear flexural behavior of corroded reinforced concrete beams. For this purpose, a series of test and an analytical simulation using the Maaddawy's model were carried. Test specimens of total 12 RC beams were placed in accelerated corrosion status using salt water spray test chamber for 5 months and 10 months, after they were preloaded up to 30% and 60% of the maximum load corresponding to nominal flexural strength. The test results showed that flexural strength and ductility decreased to 5.4% and 43% at the most respectively due to breakdown of bond at the steel-concrete interface. Comparative study between the analytical predictions and the experimental results showed that the Maaddawy's model can be applied to predict a real corroded RC flexural members.

• Steel and Composite Structures
• /
• v.31 no.3
• /
• pp.303-317
• /
• 2019

This paper presents a finite element model for predicting the behaviour of high-strength steel bolted beam-to-column joints under monotonic loading. The developed numerical model considers the effects of material nonlinearities and geometric nonlinearities. The accuracy of the developed model is examined by comparing the predicted results with independent experimental results. It is demonstrated that the proposed model accurately predicts the ultimate flexural resistances and moment-rotation curves for high-strength steel bolted beam-to-column joints. Mechanical performance of three joint configurations with various design details is examined. A parametric study is carried out to investigate the effects of key design parameters on the behaviour of bolted beam-to-column joints with double-extended endplates. The plastic flexural capacities of the beam-to-column joints from the experimental programme and numerical analysis are compared with the current codes of practice. It is found that the initial stiffness and plastic flexural resistance of the high-strength steel beam-to-column joints are overestimated. Proper modifications need to be conducted to ensure the current analytical method can be safely used for the bolted beam-to-column joints with high-performance materials.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2004.05a
• /
• pp.520-523
• /
• 2004

The finite element method(FEM) models were developed for the reinforced concrete flexural walls and analysed under constant axial and monotonic lateral load using ABAQUS. The major objective of the present study is to determine if the ABAQUS finite element program can be used to accurately model the post-cracked mode of failure in plastic regions of walls, and, if so, to develop practical failure criteria in the plastic range of the material response. The research comprises constitutive models to represent behavior of the materials that compose a wall on the basis of experimental data, development of techniques that are appropriate for analysis of reinforced concrete structures, verification, and calibration of the global model for reinforced concrete walls of increasing complexity. Results from the analyses of these FEM models offers significant insight into the flexural behavior of benchmark data.

• Computers and Concrete
• /
• v.17 no.4
• /
• pp.489-498
• /
• 2016

In this paper, the flexural strength ($f_{fs}$) and splitting tensile strength ($f_{sts}$) of concrete containing different proportions of fly ash have been modeled by using gene expression programming (GEP). Two GEP models called GEP-I and GEP-II are constituted to predict the $f_{fs}$ and $f_{sts}$ values, respectively. In these models, the age of specimen, cement, water, sand, aggregate, superplasticizer and fly ash are used as independent input parameters. GEP-I model is constructed by 292 experimental data and trisected into 170, 86 and 36 data for training, testing and validating sets, respectively. Similarly, GEP-II model is constructed by 278 experimental data and trisected into 142, 70 and 66 data for training, testing and validating sets, respectively. The experimental data used in the validating set of these models are independent from the training and testing sets. The results of the statistical parameters obtained from the models indicate that the proposed empirical models have good prediction and generalization capability.

• Computers and Concrete
• /
• v.17 no.4
• /
• pp.477-488
• /
• 2016

This paper aims to model the effects of five different variables which includes: cement content (C), the steel fiber amount (F), the silica fume amount (SF), the superplasticizer (SP), the silica fume amount (SF), and the water to cementitious ratio (w/c) on 28 days flexural toughness of Ultra High Performance Concrete (UHPC) as well as, a study on the variable interactions and correlations by using analyze of variance (ANOVA) and response surface methodology (RSM). The variables were compared by fine aggregate mass. The model will be valid for the mixes with 0.18 to 0.32 w/c ratio, 4 to 8 percent steel fiber, 7 to 13 percent cement, 15 to 30 percent silica fume, and 4 to 8 percent superplasticizer by fine aggregate mass.

• Computers and Concrete
• /
• v.8 no.3
• /
• pp.357-369
• /
• 2011

In this study, effect of steel fibers on toughness and some mechanical properties of concrete were investigated. Hooked-end steel fibers were used in concrete samples with three volume fractions (${\nu}_f$) of 0.5%, 0.75% and 1% and for two aspect ratios (l/d) of 45 and 65. Compressive and flexural tensile strength and modulus of elasticity of concrete were determined for cylindrical, cubic and prismatic samples at the age of 7 and 28 days. The stress-strain curves of standard cylindrical specimens were studied to determine the effect of steel fibers on toughness of steel-fiber-reinforced concrete (SFRC). In addition, the relationship between compressive strength and the flexural tensile strength of SFRC were reported. Finally, a simple model was proposed to generate the stress-strain curves for SFRC based on strains corresponding to the peak compressive strength and 60% of peak compressive stress. The proposed model was shown to provide results in good correlation with the experimental results.