scholarly journals An effective model for analysis of reinforced concrete members and structures under blast loading

2016 ◽  
Vol 19 (12) ◽  
pp. 1815-1831 ◽  
Author(s):  
Zhongxian Li ◽  
Bo Zhong ◽  
Yanchao Shi
Keyword(s):  
Reinforced Concrete ◽  
Seismic Analysis ◽  
Damage Effect ◽  
Computational Time ◽  
Isotropic Hardening ◽  
High Fidelity ◽  
Beam Model ◽  
Blast Loads ◽  
Concrete Members ◽  
Proposed Model

The traditional fiber beam model has been widely used in the seismic analysis of reinforced concrete members and structures. However, the inability to capture shear failure restricts its application to blast loadings. In this article, a numerical model that considers both rate-dependent shear behavior and damage effect is proposed based on the traditional fiber beam element. This is achieved using the modified compression-field theory with a concrete damage model and bilinear steel model in the principal directions. Meanwhile, a condensed three-dimensional stress–strain relation from the isotropic hardening plasticity model is implemented to simulate longitudinal reinforcement bars, as large shear strain would be produced under severe blast loads. The proposed model is validated by comparing the numerical and test results. The high-fidelity physics-based finite element model, validated by the same experiment, is also used in the study to prove the efficiency of the proposed model. Case studies of a reinforced concrete beam and a six-story reinforced concrete frame structure subjected to blast loads are then carried out. The results indicate that the proposed model is reliable compared with the high-fidelity physics-based model. In addition to the accuracy, comparisons of the computational time show an excellent performance with respect to the efficiency of the proposed model.

scholarly journals ELASTIC-PLASTIC FRACTURE ANALYSIS OF STRUCTURAL COLUMNS

2006 ◽  
Vol 12 (2) ◽  
pp. 181-186 ◽  
Author(s):  
Abdesselam Zergua ◽  
Mohamed Naimi
Keyword(s):  
Reinforced Concrete ◽  
Cross Sections ◽  
Correlation Study ◽  
Flow Rule ◽  
Elastic Plastic ◽  
Concrete Members ◽  
Proposed Model ◽  
Compression Region ◽  
Frame Work ◽  
Compressive Axial Load

This research is achieved in the general frame‐work of the study of the concrete behaviour. It has for objective the development of a numerical tool able to predict the behaviour of reinforced concrete columns with circular and square cross‐sections under an increasing compressive axial load. The concrete behaviour is assumed as elastic‐plastic model with an associated flow rule in compression region and as elastic with tension stiffening behaviour in the tension region. Two yield surfaces have been taken into account according to the Drucker‐Prager and Rankine failure criterions. However, the reinforcing steel is assumed as an elastic strain hardening model. A finite element method using solid cube elements for concrete, and bar elements for the reinforcement have been used. Correlation study between numerical and experimental results is conducted with the objective to establish the validity of the proposed model and identify the significance of the transverse reinforcement volumetric ratio effect on the response of reinforced concrete members. Good agreement has been observed in comparing these results.

scholarly journals Estimation of Minimum Torsional Reinforcement of Reinforced Concrete and Steel Fiber-Reinforced Concrete Members

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Hyunjin Ju ◽  
Sun-Jin Han ◽  
Dichuan Zhang ◽  
Jong Kim ◽  
Wei Wu ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Steel Fiber ◽  
Torsion Test ◽  
Reinforcement Ratio ◽  
Fiber Reinforced Concrete ◽  
Test Results ◽  
Fiber Reinforced ◽  
Steel Fiber Reinforced Concrete ◽  
Concrete Members ◽  
Proposed Model

The current code specifies a minimum torsional reinforcement ratio to prevent possible brittle failure after torsional cracking in concrete members. However, since there are many researches, in which even the concrete members with the minimum torsional reinforcement fail to secure sufficient reserved strength after torsional cracking, continuous research needs to be carried out. Accordingly, in the authors’ previous research, a minimum torsional reinforcement ratio was proposed based on the reserved strength concept and was extended to the steel fiber-reinforced concrete members in order to suggest the minimum fiber factor as the minimum torsional reinforcement ratio. In the present study, a pure torsion test was carried out on reinforced concrete and steel fiber-reinforced concrete members after a brief introduction on the above, and the proposed model was verified based on the test results. The test results of six torsional specimens were compared with those of the proposed model, and it was found that the proposed model provides a reasonable evaluation on the torsional failure mode of the specimen according to the reserved strength ratio.

scholarly journals Uniaxial Bond Stress-Slip Relationship of Reinforcing Bars in Concrete

2012 ◽  
Vol 2012 ◽  
pp. 1-12 ◽  
Author(s):  
Sungnam Hong ◽  
Sun-Kyu Park
Keyword(s):  
Reinforced Concrete ◽  
Bond Stress ◽  
Analytical Models ◽  
Cross Sectional ◽  
Concrete Members ◽  
Axial Tension ◽  
Analytical Results ◽  
Proposed Model ◽  
Relationship Of ◽  
Tension Loading

This paper documents a study carried out on the estimation of the bond stress-slip relationship for reinforced concrete members under axial tension loading. An analytical model is proposed that utilizes the conventional bond stress-slip theories as well as the characteristics of deformed bar and concrete cross-sectional area. An equation for the estimation of the bond stress is formulated as the function of nondimensional factors (e.g., bond stress, slip, etc.). The validity, accuracy, and efficiency of the proposed model are established by comparing the analytical results with the experimental data and the JSCE design codes, as well as the analytical models given by Ikki et al. and Shima. The analytical results presented in this paper indicate that the proposed model can effectively estimate the bond stress-slip relationship of reinforced concrete members under axial tension loading.

SIMPLIFIED APPROACH FOR SEISMIC ANALYSIS OF STRUCTURES

2002 ◽  
Vol 02 (02) ◽  
pp. 207-225 ◽  
Author(s):  
VETO VARMA ◽  
G. R. REDDY ◽  
K. K. VAZE ◽  
H. S. KUSHWAHA
Keyword(s):  
3D Model ◽  
Seismic Analysis ◽  
Computational Time ◽  
Beam Model ◽  
Structural Behaviour ◽  
Lumped Mass ◽  
Local Modes ◽  
Simplified Approach ◽  
Energy Equivalence ◽  
Mass Participation

The seismic analysis of a structure using continuum mechanics approach may yield good results. However, this approach is difficult to apply for complex geometrical problems such as nuclear reactor containment building. To incorporate the entire structural behaviour, a full 3D model is best suited. However, a large number of modes are required to achieve at least 90% mass participation or frequency content up to 33 Hz. This consumes a large computational time due to large number of local modes present. Therefore, an equivalent lumped mass beam model, which as compared to 3D model, is much simpler and produces conservative global responses, has been considered in analysis. The lumped mass equivalent beam model of the system can be prepared after carrying out static analysis of 3D model using static energy equivalence approach. Forces and moments obtained by the seismic analysis of this beam model can be applied on the 3D model in order to obtain stresses in each element. It was found that the results obtained by this approach gives higher results because of higher mass participation. Experimental investigation is also performed on one of the case study to support the analysis. Hence it is concluded that analysis using beam model based on strain energy equivalence, in combination with 3D model is much simpler, economic and gives conservative results.

SEISMIC ANALYSIS OF MULTISTOREY REINFORCED CONCRETE STRUCTURES

2019 ◽  
Vol 9 (1) ◽  
pp. 61
Author(s):  
SINGH RAVIKANT ◽  
KUMAR SINGH VINAY ◽  
YADAV MAHESH ◽  
◽  
◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Seismic Analysis ◽  
Concrete Structures ◽  
Reinforced Concrete Structures

scholarly journals Improved Modeling of a Multi-Level Inverter for TACS to Reduce Computational Time and Improve Accuracy

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 849
Author(s):  
Sung-An Kim
Keyword(s):  
Mechanical Model ◽  
Simulation Software ◽  
Computational Time ◽  
Electrical Model ◽  
Conventional Model ◽  
Switching Operation ◽  
Air Compressor ◽  
Power Semiconductors ◽  
Proposed Model ◽  
Multi Level

A modeling of a turbo air compressor system (TACS), with a multi-level inverter for driving variable speed, combining an electrical model of an electric motor drive system (EMDS) and a mechanical model of a turbo air compressor, is essential to accurately analyze dynamics characteristics. Compared to the mechanical model, the electrical model has a short sampling time due to the high frequency switching operation of the numerous power semiconductors inside the multi-level inverter. This causes the problem of increased computational time for dynamic characteristics analysis of TACS. To solve this problem, the conventional model of the multi-level inverter has been proposed to simplify the switching operation of the power semiconductors, however it has low accuracy because it does not consider pulse width modulation (PWM) operation. Therefore, this paper proposes an improved modeling of the multi-level inverter for TACS to reduce computational time and improve the accuracy of electrical and mechanical responses. In order to verify the reduced computational time of the proposed model, the conventional model using the simplified model is compared and analyzed using an electronic circuit simulation software PSIM. Then, the improved accuracy of the proposed model is verified by comparison with the experimental results.

Research on Shear Bearing Capacity of Reinforced Concrete Short Beam in Salt-Fog Environment

2012 ◽  
Vol 455-456 ◽  
pp. 1079-1083
Author(s):  
Wei Jun Yang ◽  
Hong Jia Huang ◽  
Wen Yu Jiang ◽  
Yi Bin Peng
Keyword(s):  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Salt Spray ◽  
Test Chamber ◽  
Shear Capacity ◽  
Salt Spray Test ◽  
Concrete Members ◽  
Short Beam ◽  
Shear Bearing Capacity ◽  
Salt Fog

Shantou atmospheric salt-fog environment is simulated with the comprehensive salt spray test chamber. By using reinforced concrete short beams under different water-cement radio, different corrosion time, the inclined section degradation rules of the corrosive reinforced concrete members are researched for establishing shear capacity of short beam formulas in salt-fog environment.

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