Seismic Vulnerability Assessment and Retrofit Design of Poly Villa Building, Dhaka, Bangladesh

• Client: USAID, Bangladesh
• Project Year: 2015
• Location: Gulshan, Bangladesh

In 2015, ESS undertook a comprehensive seismic vulnerability assessment and retrofit design for the Poly Villa building in Dhaka, Bangladesh. The primary objective was to identify structural deficiencies and propose effective intervention strategies to enhance the building’s seismic performance.

Assessment Methodology:

• Visual Inspection: A thorough examination of the building’s exterior and interior to identify visible signs of damage or deterioration.
• Non-Destructive Testing: Techniques such as ultrasonic pulse velocity testing and rebound hammer tests are used to evaluate the material properties of building elements.
• In-Situ Testing: Intrusive tests like in-plane shear tests to assess the condition and properties of mortar used in the building.
• Laboratory Testing: Material property testing, including compressive strength tests on bricks, to inform the structural analysis.
• Structural Analysis: Detailed analysis using empirical formulas to determine the mechanical properties of the masonry and assess the building’s seismic performance.

Tasks performed by ESS

1. Literature Review:
   • Gather relevant information on seismic design standards, building materials, and retrofit techniques applicable to masonry structures in Bangladesh.
   • Identify potential vulnerabilities and best practices for seismic retrofitting.
2. Site Investigation and Data Collection:
   • Conduct a thorough visual inspection of the building to identify existing damage or signs of distress.
   • Collect information on building history, construction materials, and occupancy.
   • Perform non-destructive testing to assess the material properties of walls, floors, and other structural elements.
   • Conduct in-situ tests, such as in-plane shear tests, to evaluate the condition of mortar joints.
   • Collect samples of construction materials for laboratory testing.
3. Structural Analysis:
   • Develop a structural model of the building using appropriate software.
   • Determine the mechanical properties of masonry components based on laboratory testing and empirical formulas.
   • Analyze the building’s response to seismic loads using dynamic analysis techniques.
   • Assess the building’s vulnerability to collapse under different earthquake scenarios.
4. Retrofit Design:
   • Identify critical structural deficiencies and propose appropriate retrofit strategies.
   • Develop detailed design drawings and specifications for retrofit measures.
   • Consider cost-effectiveness, constructability, and long-term performance of proposed interventions.
5. Cost-Benefit Analysis:
   • Evaluate the economic benefits of retrofitting the building, including potential savings from reduced insurance premiums and avoided losses in case of an earthquake.
   • Compare the costs of different retrofit options and select the most cost-effective solution.
6. Implementation Plan:
   • Develop a detailed implementation plan, including scheduling, resource allocation, and quality control measures.
   • Coordinate with building owners, contractors, and regulatory authorities to ensure smooth execution of the retrofit project.
7. Monitoring and Evaluation:
   • Establish a monitoring system to track the progress of retrofit work and ensure compliance with design specifications.
   • Conduct post-retrofit inspections to verify the effectiveness of the interventions and address any issues that may arise.