ASSESSMENT OF OUT-OF-PLANE FAILURE OF NON-ENGINEERED MASONRY WALL DUE TO STORM SURGES
Keywords:Storm surge, Typhoon Haiyan, Out-of-plane failure, Masonry walls, Yield line method
Typhoon Haiyan, in 2013, caused massive destruction in the central Visayan region in the Philippines. Failure due to the collapse of non-engineered masonry walls was the most common failure experienced by residential structures in the area. This exposed the high vulnerability of non-engineered masonry walls of residential structures in rural areas against extreme events. Existing building codes for reinforced concrete structures ensure it to perform well against extreme event within Code’s anticipated magnitude. However, masonry walls of low-rise structures along coastal areas did not fare well and exhibited high vulnerability to out-of-plane failures due to poor construction methodology and improper design practice. In this study, on-site survey along coastal barangays of Tacloban City was conducted to determine the method of construction and design consideration for masonry walls. The structural investigation of masonry walls utilized finite element modeling (elastic) and yield line method (plastic). The estimated maximum pressure capacity using yield line method for the non-engineered masonry walls and its compliance to National Structural Code of the Philippines (NSCP 2015)/ACI 530-02 was found to be inadequate. Hence, the improved design was proposed and then assessed against similar loads. Improvements in the design include modification in spacing and size of steel reinforcements, an increase in concrete hollow block thickness, and modifications on masonry wall dimensions. Based on analytical results, the maximum pressure capacity of the improved design increased by 2 to 3 times compared to the current non-engineered masonry wall design.