POST-EARTHQUAKE BUILDING SAFETY EVALUATIONS in KATHMANDU VALLEY Observations & Recommendations

Kathmandu, Nepal POST-EARTHQUAKE BUILDING SAFETY EVALUATIONS IN KATHMANDU VALLEY Observations & Recommendations June 2015 REPORT M7.8 Gorkha Earthquake Post-Earthquake Building Safety Evaluations in the Kathmandu Valley Observations and Recommendations Kathmandu, Nepal June 2015 Prepared for Homraj Acharya, Country Director Global Fairness Initiative Kathmandu, Nepal Prepared by Sabina S. Surana, P.E. 728 134th Street SW Suite 200 Everett, WA 98204 U.S.A. 425/741-3800 Fax 425/741-3900 www.reidmiddleton.com Table of Contents Page No. ACKNOWLEDGEMENTS ............................................................................................................................. 3 1.0 INTRODUCTION ..................................................................................................................................... 1 2.0 BUILDING CONSTRUCTION TYPES ..................................................................................................... 2 3.0 STRUCTURAL ASSESSMENT OBSERVATIONS ................................................................................. 6 4.0 RECOMMENDATIONS ......................................................................................................................... 19 Appendix List Appendix A: Checklists Used in Nepal Appendix B: Damaged Assessment Guidelines provided by GFI Appendix C: Indian Standard - Repair and Seismic Strengthening of Buildings - Guidelines Appendix D: Tip 12: How do Brick Masonry Houses behave during Earthquake? Appendix E: Tip 13: Why Masonry Building should have Simple Structural Configuration? Appendix F: Tip14: Why Horizontal Bands are required in Masonry Buildings? Appendix G: Tip 15: Why is Vertical Reinforcement required in Masonry Buildings? Appendix H: Tip 16: How to make Stone Masonry Buildings Earthquake Resistant? Appendix I: Tip 17: How do Earthquakes Affect Reinforced Concrete Building? Appendix J: Tip 18: How do Beams in RC Building Resist Earthquakes? Appendix K: Tip 19: How do Columns in RC Building Resist Earthquakes? Appendix L: Tip 20: How do Beam-Column Joints in RC Building Resist Earthquakes? Appendix M: Tip 21: Why are Open-Ground Storey Buildings Vulnerable in Earthquakes? Appendix N: Seismic Safety for Adobe Homes Appendix O: Boundary Wall Construction Guide Appendix P: American Society of Civil Engineers Code of Ethics Appendix Q: References List of Figures FIGURE 1. BUILDING SAFETY ASSESSMENT PERFORMANCE AREA (REID MIDDLETON). ......................................... 1 FIGURE 2. TYPICAL RC FRAME BUILDING WITH BRICK INFILL CONSTRUCTION (SURANA). ..................................... 2 FIGURE 3. UNREINFORCED LOAD BEARING BRICK BUILDING IN PHUTUNG, KATHMANDU (SURANA). ....................... 3 FIGURE 4. UNREINFORCED LOAD BEARING BRICK WITH MUD MORTAR BUILDING IN PHUTUNG, KATHMANDU (SURANA). ............................................................................................................................................... 4 FIGURE 5. UNREINFORCED LOAD BEARING ADOBE BUILDING IN PHUTUNG, KATHMANDU (SURANA). ..................... 4 FIGURE 6. BAMBOO FLOOR SYSTEM IN UNREINFORCED LOAD BEARING BUILDING, KATHMANDU (SURANA). .......... 5 FIGURE 7. RC FRAME BUILDING BEHAVIOUR DURING EARTHQUAKE (IITK-BMTPC EARTHQUAKE TIP 17). ............ 7 FIGURE 8. BEAM-COLUMN JOINT BEHAVIOUR DURING EARTHQUAKE (IITK-BMTPC EARTHQUAKE TIP 20). ........... 7 FIGURE 9. SOFT STOREY BUILDING BEHAVIOUR DURING EARTHQUAKE (IITK-BMTPC EARTHQUAKE TIP 21). ....... 7 FIGURE 10. SOFT STOREY FAILURE ON RC FRAME STRUCTURE IN LUBHU, KATHMANDU (SURANA). ..................... 8 REPORT June 2015 Nepal Post-Earthquake Building Safety Evaluations 1 FIGURE 11. COLUMN BASE DAMAGE ON RC FRAME BUILDING IN DHARMASTHALI, KATHMANDU (SURANA). ........... 8 FIGURE 12. FAILURE AT COLUMN JOINT ON RC FRAME BUILDING IN KANTIPUR PUBLICATION BUILDING, KATHMANDU (SURANA). ............................................................................................................................ 9 FIGURE 13. BRICK INFILL WALL DAMAGE ON RC FRAME BUILDING IN HATTIBAN, KATHMANDU (SURANA). .......... 10 FIGURE 14. POORLY CONSTRUCTED BRICK INFILL WALL IN PHUTUNG, KATHMANDU (SURANA)........................... 10 FIGURE 15. BRICK MASONRY BUILDING BEHAVIOR DURING EARTHQUAKE (IITK-BMTPC EARTHQUAKE TIP 12). 11 FIGURE 16. PARTIAL OR COMPLETE COLLAPSE OF UNREINFORCED LOAD BEARING BRICK STRUCTURES IN DHARMASTHALI, KATHMANDU (SURANA).................................................................................................. 12 FIGURE 17. DIAGONAL SHEAR CRACKS AND CORNER SEPARATION IN UNREINFORCED LOAD BEARING BRICK STRUCTURE IN KATHMANDU (SURANA). ................................................................................................... 12 FIGURE 18. OUT-OF-PLANE WALL FAILURE IN UNREINFORCED LOAD BEARING BRICK STRUCTURES IN DURBAR HIGH SCHOOL, KATHMANDU (SURANA). ................................................................................................... 13 FIGURE 19. ROOFTOP WATER TANK SUPPORT FAILURE IN JORPATI, KATHMANDU (SURANA). ............................. 14 FIGURE 20. ROOFTOP WATER HEATER SUPPORT FAILURE IN JORPATI, KATHMANDU (SURANA). ......................... 15 FIGURE 21. DAMAGE AT CONSTRUCTION JOINT IN ASIAN INSTITUTE OF TECHNOLOGY AND MANAGEMENT, KATHMANDU (SURANA). .......................................................................................................................... 16 FIGURE 22. COLLAPSED UNREINFORCED BRICK BOUNDARY WALL IN ASIAN INSTITUTE OF TECHNOLOGY AND MANAGEMENT, KATHMANDU (SURANA). ................................................................................................... 17 FIGURE 23. TYPICAL SEISMIC JOINT IN NEPAL MEDICAL COLLEGE BUILDING, KATHMANDU (SURANA). ................ 17 FIGURE 24. BOOK SHELVES IN LIBRARY OF MINISTRY OF GENERAL ADMINISTRATION, KATHMANDU (SURANA). ... 18 FIGURE 25. STRENGTHENING RC COLUMN BY JACKETING (IS 13935, 1993). .................................................... 19 FIGURE 26. STRENGTHENING RC BEAMS BY JACKETING (IS 13935, 1993). ...................................................... 20 FIGURE 27. INCREASING RC COLUMN FLEXURAL STRENGTH BY CONTINUING LONGITUDINAL REINFORCEMENT THROUGH EXISTING CONCRETE SLAB (UNIDO MANUAL). ......................................................................... 20 FIGURE 28. FRP APPLICATION ON EXISTING RC FRAME BUILDING (THE SHAKEOUT SCENARIO, SUPPLEMENTAL STUDY). ................................................................................................................................................. 21 FIGURE 29. STRUCTURAL RESTORATION OF CRACKED MASONRY WALLS (IS 13935, 1993). .............................. 22 FIGURE 30. GROUT OR EPOXY INJECTION IN EXISTING WEAK WALLS (IS 13935, 1993). .................................... 23 FIGURE 31. SEWING TRANSVERSE WALLS WITH INCLINED BARS TO REINFORCE CORNERS (IS 13935, 1993) ....... 23 FIGURE 32. STRENGTHENING WITH WIRE-MESH AND MORTAR (IS 13935, 1993) ................................................ 24 FIGURE 33. SECURE ROOFTOP WATER TANK AND PROVIDE FRAMING CONNECTION TO ROOF SLAB (NSET) ....... 25 FIGURE 34. BOOKSHELVES CONNECTIONS TO WALL AND FLOOR (NSET) ......................................................... 25 FIGURE 35. SUSPENDED CEILING SYSTEM -- GENERAL BRACING ASSEMBLY (FEMA E-74) ................................ 26 FIGURE 36. VERTICAL TANK CONNECTION (FEMA E-74) ................................................................................. 26 REPORT June 2015 Nepal Post-Earthquake Building Safety Evaluations 2 Acknowledgements The author would like to thank David B. Swanson, P.E., S.E., Structural Group Director at Reid Middleton, Inc., who dedicated his time and expertise to provide suggestions as a reviewer; her firm Reid Middleton, Inc., for funding her time; and her colleagues for allowing her time away from her design practice to work as a volunteer in her home country of Nepal. The author is especially thankful to Global Fairness Initiative for organizing, deploying, and funding travel costs for volunteer structural engineers to conduct safety assessments of damaged buildings in Nepal and to International Masonry Institute for publishing the call for volunteers. Special thanks to Lenny Anderson of Reid Middleton, Inc., for his assistance with the report cover and graphics. REPORT June 2015 Nepal Post-Earthquake Building Safety Evaluations 3 1.0 Introduction The purpose of this report is to present the author’s observations, findings, and recommendations at the request of Homraj Acharya, Country Director for Global Fairness Initiative (GFI) and as a follow up to volunteer service performing rapid post-earthquake safety evaluations of damaged buildings in the Kathmandu valley in Nepal. In May 2015, following the magnitude M7.8 Gorkha Earthquake that struck Nepal on April 25, 2015, GFI deployed volunteer structural engineers from the United States to provide rapid post-earthquake safety evaluations of damaged buildings. The team travelled to Nepal at the request of the Nepalese government and in collaboration with GFI’s local partners Brick Clean Nepal and MinErgy. The primary mission of the team was to perform rapid post-earthquake safety evaluations of damaged buildings in the Kathmandu valley and to assist local authorities and residents in determining whether their structures were safe to occupy. The team performed building safety evaluation assessments alongside volunteer Nepalese engineers deployed by the Nepal Engineering Association (NEA). This report summarizes the observations,

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