Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 32726
The Influence of Strengthening on the Fundamental Frequency and Stiffness of a Confined Masonry Wall with an Opening for а Door

Authors: Emin Z. Mahmud


This paper presents the observations from a series of shaking-table tests done on a 1:1 scaled confined masonry wall model, with opening for a door – specimens CMDuS (confined masonry wall with opening for a door before strengthening) and CMDS (confined masonry wall with opening for a door after strengthening). Frequency and stiffness changes before and after GFRP (Glass Fiber Reinforced Plastic) wall strengthening are analyzed. Definition of dynamic properties of the models was the first step of the experimental testing, which enabled acquiring important information about the achieved stiffness (natural frequencies) of the model. The natural frequency was defined in the Y direction of the model by applying resonant frequency search tests. It is important to mention that both specimens CMDuS and CMDS are subjected to the same effects. The tests are realized in the laboratory of the Institute of Earthquake Engineering and Engineering Seismology (IZIIS), Skopje. The specimens were examined separately on the shaking table, with uniaxial, in-plane excitation. After testing, samples were strengthened with GFRP and re-tested. The initial frequency of the undamaged model CMDuS is 13.55 Hz, while at the end of the testing, the frequency decreased to 6.38 Hz. This emphasizes the reduction of the initial stiffness of the model due to damage, especially in the masonry and tie-beam to tie-column connection. After strengthening of the damaged wall, the natural frequency increases to 10.89 Hz. This highlights the beneficial effect of the strengthening. After completion of dynamic testing at CMDS, the natural frequency is reduced to 6.66 Hz.

Keywords: Behavior of masonry structures, Eurocode, fundamental frequency, masonry, shaking table test, strengthening.

Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 475


[1] L. Krstevska, and A. Poposka Shake table test of masonry wall specimens in scale 1:1 - IZIIS – REPORT 2019-34 IZIIS - Dynlab, Skopje.
[2] E. Mahmud, and E. Abdulahad, “Shaking table tests determining frequency and stiffness before and after strengthening of a confined masonry wall without an opening,” unpublished.
[3] E. Mahmud “The influence of strengthening on the fundamental frequency and stiffness of a confined masonry wall with an opening for а window,” in ICAMMS 2020 : International Conference on Advances in Masonry Materials and Structures, 2020.
[4] I. Corbi, and Z. Rakicevic, “Shaking Table Testing for Structural Analysis,” in International Journal of Mechanics, vol. 7, no. 4, pp. 459–466, 2013.
[5] Jimin He, and Zhi-Fang Fu, “Modal Analysis,” Butterworth-Heinemann, 2001.
[6] D. J. Ewins, Modal Testing: Theory, Practice and Application. Research Studies Press LTD: Baldock, Hertfordshire, England, 2000.
[7] E. Abdulahad, and E. Mahmud, “Implementation of Samples and Preparatory Activities before Dynamic Tests,” in Annual of the University of Architecture, Civil Engineering and Geodesy, vol. 52, no. 3, pp. 891–900, Sofia, Bulgaria, 2019.
[8] Eurocode 8: Design of structures for earthquake resistance, European Committee for Standardization, 2005.
[9] S. Brzev, and R. Meli, R. “International Guideline for Seismic Design of Low-Rise Confined Masonry Buildings in Regions of High Seismic Risk,” in The 15th World Conference on Earthquake Engineering (15WCEE), Lisbon, Portugal, 2012.
[10] S. Jain, S. Brzev, L. Bhargava, D. Basu, I. Ghosh, D. Rai, and K. Ghaisas, Confined Masonry for Residential Buildings. Gandhinagar: Indian Institute of Technology, 2015.
[11] V. Singhal, and D. Rai, “Seismic Behavior of Confined Masonry Walls When Subjected to In-Plane and Out-of-Plane Loading,” in Tenth U.S. National Conference on Earthquake Engineering. Anchorage, Alaska, 2014a.
[12] V. Singhal, and D. Rai, “Role of Toothing on In-Plane and Out-of-Plane Behavior of Confined Masonry Walls,” in Journal of Structural Engineering, 2014b.
[13] Eurocode 6: Design of masonry structures, European Committee for Standardization, 2005.
[14] Eurocode 2: Design of concrete structures, European Committee for Standardization, 2005.