A test arrangement for experimental and numerical demonstration of pinching effect in reinforced concrete structures.

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Journal Title

Journal ISSN

Volume Title

Insinööritieteiden korkeakoulu | Master's thesis

Authors

Date

2017-10-30

Department

Major/Subject

Structural Engineering

Mcode

ENG3039

Degree programme

Master's Programme in Structural Engineering

Language

en

Pages

54+9

Series

Abstract

Pinching is the degradation of stiffness in hysteretic curve during the loading and unloading cycles. Pinching in reinforced concrete within a linear regime is caused due to the bond slippage between steel and concrete, opening and closing of cracks and shear locking mechanism. In conventional large-scale tests, it is difficult to observe visually the bond slip or gap opening between the steel and concrete as the reinforcement is embedded in the concrete. Therefore, an experimental setup has been devised in which it is possible to observe the bond-slip due to cyclic movement of the steel bar. A simple model has been devised for this purpose that would help to focus on the bond-slip and its effect on the hysteretic behavior of the concrete model. Numerical simulation of the setup has been done by Finite Element software ABAQUS through ABAQUS/Standard analysis. ABAQUS does not recognize the pinching effect in concrete directly therefore, to simulate the bond-slip behavior use of non-linear springs has been utilized. A comparison between the experimental and numerical results is given in this thesis. The numerical method predicts the stiffness degradation in the system but there is a more pronounced hysteretic curve in the numerical results than the experimental results. The reason for the difference between the numerical and experimental results has been given and suggestions for improving the test arrangement have been given in this report. Once simulation results can be improved, it can help to form simple models, which can simulate pinching in ABAQUS.

Description

Supervisor

Puttonen, Jari

Thesis advisor

Puttonen, Jari

Keywords

pinching, stiffness degradation, hysteresis, reinforced concrete, bond-slip, nonlinear spring

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Citation

Permanent link to this item

https://urn.fi/URN:NBN:fi:aalto-201711277791

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[dipl] Insinööritieteiden korkeakoulu / ENG