In-Plane Seismic Response of URM Walls Upgraded with FRP
Publication: Journal of Composites for Construction
Volume 9, Issue 6
Abstract
Recent earthquakes have shown the vulnerability of unreinforced masonry (URM) buildings, which have led to an increasing demand for techniques to upgrade URM buildings. Fiber reinforced polymer (FRP) can provide an upgrading alternative for URM buildings. This paper presents results of dynamic tests investigating the in-plane behavior of URM walls upgraded with FRP (URM-FRP). These tests represent pioneer work in this area (dynamic and in-plane). Five half-scale walls were built, using half-scale brick clay units, and upgraded on one face only. Two moment/shear ratios (1.4 and 0.7), two mortar types (M2.5 and M9), three composite materials (carbon, aramid, and glass), three fiber structures (plates, loose fabric, and grids), and two upgrading configurations (diagonal “X” and full surface shapes) were investigated. The test specimens were subjected to a series of synthetic earthquake motions with increasing intensities on a uniaxial earthquake simulator. The tests validate the effectiveness of the one side upgrading: the upgrading technique improved the lateral resistance of the URM walls by a factor ranging from 1.3 to 2.9; however, the improvement in the lateral drift was less significant. Moreover, no uneven response was observed during the test due to the single side upgrading. Regarding the upgrading configurations, the bidirectional surface type materials (fabrics and grids) applied on the entire surface of the wall (and correctly anchored) can help postpone the three classic failure modes of masonry walls: rocking (“flexural failure”), step cracking, and sliding (“shear failures”). Additionally, in some situations, they will postpone collapse by “keeping the bricks together” under large seismic deformations. On the other hand, the diagonal “X” shape was less successful and premature failure was developed during the test.
Get full access to this article
View all available purchase options and get full access to this article.
Acknowledgments
The financial support provided by SIKA and the Swiss Commission for Technological Innovation (CTI) is gratefully acknowledged. Appreciation is also extended to ETHZ for the use of the testing facility. The fabrication of the half-scale bricks by MORANDI is acknowledged.
References
Abrams, D. P., and Lynch, J. M. (2001). “Flexural behavior of retrofitted masonry piers.” Proc., KEERC-MAE Joint Seminar on Risk Mitigation for Regions of Moderate Seismicity, Ill.
Albert, M. L., Elwi, A. E., and Cheng, J. J. R. (2001). “Strengthening of unreinforced masonry walls using FRPs.” J. Comp. Constr., 5(2), 76–84.
Comite Euro-International du Béton (CEN). (1994). “Design provisions for earthquake resistance of structures.” Eurocode 8, Lausanne, Switzerland.
Ehsani, M. R., Saadatmanesh, H., and Velazquez-Dimas, J. I. (1999). “Behavior of retrofitted URM walls under simulated earthquake loading.” J. Comp. Constr., 3(3), 134–142.
ElGawady, M. A., Lestuzzi, P., and Badoux, M. (2004). “A review of retrofitting of unreinforced masonry walls using composites.” Proc., 4th International Conf. on Advanced Composite Materials in Bridges and Structures, CSCE, Calgary, Alberta, Canada.
ElGawady, M. A., Lestuzzi, P., and Badoux, M. (2003). “Dynamic tests on URM walls before and after upgrading with composites.” Experimental Rep., Publication No. 1, IMAC ENAC, EPFL, Switzerland.
Holberg, M., and Hamilton, R. (2002). “Strengthening URM with GFRP composites and ductile connections.” Earthquake Spectra, 18(1), 63–84.
Lestuzzi, P., Wenk, T., and Bachmann, H. (1999). “Dynamic tests of RC structural walls on the ETH earthquake simulator.” Rep. No. 240, Dept. of Civil, Environmental and Geomatics Engineering, Institute of Structural Engineering, Swiss Federal Institute of Technology, Zurich, Switzerland.
Schwegler, G. (1994). “Masonry construction strengthened with fiber composites in seismically endangered zones.” Proc., 10th ECEE, Vienna, Austria, 2299–2303.
Information & Authors
Information
Published In
Journal of Composites for Construction
Volume 9 • Issue 6 • December 2005
Pages: 524 - 535
Copyright
© 2005 ASCE.
History
Received: Dec 11, 2003
Accepted: Feb 15, 2005
Published online: Dec 1, 2005
Published in print: Dec 2005
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.