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Evaluation of Seismic Performance of Adobe Dome-roof Structures Retrofitted by Steel Rods and Mesh Using Shaking Table Facility

Yekrang, Mohammad | 2010

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 40393 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engeeniring
  6. Advisor(s): Bakhshi, Ali; Ghannad, Mohammad Ali
  7. Abstract:
  8. Adobe buildings on one hand are very heavy and hence generate great amounts of inertia loads during earthquakes. Their response is also amplified in the high-frequency earthquake waves due to great stiffness. On the other hand, these structures proved vulnerable during past earthquakes because of low strength and ductility. Considering the fact that there are too many structures of this kind throughout the country and a majority of their residents are the poor, seismic retrofitting of these building should be taken as a priority rather than reconstruction. It is obvious that the proposed retrofitting technique should be simple, feasible and economical, as well. Among possible retrofitting techniques, making use of horizontal steel rods to guarantee the box-like behavior of the structure and welded steel mesh to prevent widening of walls cracks were chosen. In order to compare the response of retrofitted and unretrofitted models (which studied in the other parallel thesis), a single- story, 2:3 scale adobe building with dome roof representing buildings in seismic-prone Kerman and South Khorasan provinces is tested under Zarand earthquake (Chatrood station, 2005) taking advantage of shaking table facility and in the manner of ascending step-by-step input motion with the intensities 25%, 100%, 125%, 150% and 175% of the base intensity in the highly earthquake-prone areas (P.G.A.=0.35g). It is noteworthy that the dominant failure modes of the unretrofitted model are the main source of decision making about the retrofitting strategy. Also the basis of model selection was the database created in the first phase of this multi-staged project and a trip to Kerman province. Improvement in seismic performance of the retrofitted model was satisfactory. The model tolerated about two time's greater input energy without experiencing major damages. It is noteworthy that the major failure mode of the model was diagonal shear cracks due to torsion. This is because of Box-like behavior of the structure provided by steel rods. Also as expected, since the steel mesh was placed on the walls upper area, the cracks accumulated in the lower parts of the walls. In this manner, the main failure moe of the model was altered as detachment of perpendicular walls and collapse of roof in the first model. In order to analyze the response the model in different locations of the walls and the roof, 4 displacement-transducers and 10 acceleromeers were used. Also during excitation, the behavior of the model was captured by 13 high-speed camera and the damages were photographed after each test steps
  9. Keywords:
  10. Adobe/Mud Structures ; Seismic Performance ; Shaking Table ; Domed Roofs ; Retrofitted by Horizontal Steel Rods ; Retrofitted by Welded Steel Mesh

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