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Keywords: cracked structure, dynamic loads, CFRP, finite element method, deep beam, foundation.

Summary

Investigation on the structures after they are in operation and are subjected to environment conditions can reveal significant points for more accurate design. The results of such investigations give better a view on the performance of the structures due to their operation.

In this paper, the cracks observed in the reinforced concrete foundation of a dry mill existing in an industrial complex which has been operating for fifteen years, have been investigated. After a visit to the location of the cracks, the type of the cracks and their progress directions have been recorded for one year. Such records show that the cracks are of structural type consisted of bending and shear cracks having a width about 5.5 millimetres.

As the ratio of the span of the structure to its height is less than 5, it can be modelled as a deep beam on elastic bed and analyzed using manual method [1]. The results of the manual method can be used for evaluating the results of finite element method.

The structural details based upon the existing technical drawings and the applying loads have been considered in order to setup the finite element model of the cracked structure [2]. The model has been analyzed under static and dynamic loads and the results have been compared. The results have been also checked using the manual method by considering the structure as a deep shear span structure.

The results indicate that the location of the maximum stresses due to the dynamic loads is exactly the same as the location of the cracks. This means that the cracks have occured because of dynamic loads. The dynamic loads have been resulted from the mill rotation which has not been taken into account in the design process for the structure.

Two ways have been proposed to prevent the cracks from progressing more:

Using carbon fibre reinforced polymer (CFRP);
Strengthening the cracked areas by additional concrete and reinforcement.

For the second method, the structure has been re-analyzed after strengthening and the capability of the method has been confirmed.

References

1: Iranian Concrete Code, 1999.
2: ANSYS User Manual Revision 5.4, ANSYS Inc., Canonsburg, Pennsylvania, 1998.

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Front Page Browse CCP CSETS CTR IJRT Other Authors Search Purchase Guide FAQ Contact us	Civil-Comp Proceedings ISSN 1759-3433 CCP: 86 PROCEEDINGS OF THE ELEVENTH INTERNATIONAL CONFERENCE ON CIVIL, STRUCTURAL AND ENVIRONMENTAL ENGINEERING COMPUTING Edited by: B.H.V. Topping Paper 183 Investigation of the Cracks Observed in a Reinforced Concrete Structure M.J. Fadaee¹ and S. Gilani² ¹Department of Civil Engineering, Shahid Bahonar University, Kerman, Iran ²Islamic Azad University, Kerman Branch, Iran doi:10.4203/ccp.86.183 purchase the full-text of this paper Full Bibliographic Reference for this paper M.J. Fadaee, S. Gilani, "Investigation of the Cracks Observed in a Reinforced Concrete Structure", in B.H.V. Topping, (Editor), "Proceedings of the Eleventh International Conference on Civil, Structural and Environmental Engineering Computing", Civil-Comp Press, Stirlingshire, UK, Paper 183, 2007. doi:10.4203/ccp.86.183 Keywords: cracked structure, dynamic loads, CFRP, finite element method, deep beam, foundation. Summary Investigation on the structures after they are in operation and are subjected to environment conditions can reveal significant points for more accurate design. The results of such investigations give better a view on the performance of the structures due to their operation. In this paper, the cracks observed in the reinforced concrete foundation of a dry mill existing in an industrial complex which has been operating for fifteen years, have been investigated. After a visit to the location of the cracks, the type of the cracks and their progress directions have been recorded for one year. Such records show that the cracks are of structural type consisted of bending and shear cracks having a width about 5.5 millimetres. As the ratio of the span of the structure to its height is less than 5, it can be modelled as a deep beam on elastic bed and analyzed using manual method [1]. The results of the manual method can be used for evaluating the results of finite element method. The structural details based upon the existing technical drawings and the applying loads have been considered in order to setup the finite element model of the cracked structure [2]. The model has been analyzed under static and dynamic loads and the results have been compared. The results have been also checked using the manual method by considering the structure as a deep shear span structure. The results indicate that the location of the maximum stresses due to the dynamic loads is exactly the same as the location of the cracks. This means that the cracks have occured because of dynamic loads. The dynamic loads have been resulted from the mill rotation which has not been taken into account in the design process for the structure. Two ways have been proposed to prevent the cracks from progressing more: Using carbon fibre reinforced polymer (CFRP); Strengthening the cracked areas by additional concrete and reinforcement. For the second method, the structure has been re-analyzed after strengthening and the capability of the method has been confirmed. References 1 Iranian Concrete Code, 1999. 2 ANSYS User Manual Revision 5.4, ANSYS Inc., Canonsburg, Pennsylvania, 1998. purchase the full-text of this paper (price £20) go to the previous paper go to the next paper return to the table of contents return to the book description purchase this book (price £120 +P&P)
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