A Full-Scale Shaking Table Test on Philippine Concrete Hollow Blocks (CHB) Masonry Houses

Abstract

Most of the human casualties in past earthquakes were attributed to the collapse of buildings, particularly masonry constructions in developing countries. Most of these buildings are categorized into “Non-Engineered Construction.” In effect, these structure are spontaneously and informally constructed in various countries in a traditional manner without any or with little intervention in their design by qualified architects and engineers. Unfortunately, these types of buildings have been extensively constructed in most of the seismic prone areas in developing countries. Therefore, the safety of “Non-Engineered Construction” has become one of the most urgent issues in recent years. The concrete hollow block (CHB) masonry structures have recently become common residential structures in the Philippines. A full-scale shaking table test on CHBmasonry structures of Philippine ordinary houses was conducted in Japan. This experiment aims to acquiring a better understanding of the behavior of these structures during major earthquakes, and its results will be used to produce simple seismic evaluation methods as awareness tools, and to disseminate information on safer construction of houses in the Philippines.

Shaking table tests of a one-quarter scale model of concrete hollow block masonry houses retrofitted with fiber-reinforced paint

“…After run 25, the gable walls on north the north and south walls collapsed simultaneously. The nonretro tted house model exhibited a cracking behavior similar to that observed in the full-scale experiment, highlighting the gable wall as the most vulnerable part in the non-retro tted house model 5 . This vulnerability comes from a lack of lateral support to adjacent walls, the absence of reinforcement, and the gable wall exhibiting large displacement compared to other parts.…”

“…The mortar, which has higher compressive strength than CHB (with CHB compressive strength approximately 1 MPa), was also poured into the CHB holes without compaction. It is important to note that compaction of mortar plays a signi cant role in determining the strength of walls 5 .…”

“…The CHB with a cement-sand ratio of 1:12 exhibited the closest strength to the target. The mortar mix, consisting of cement, sand, and water with a cement-sand ratio of 1:4 and water content adjusted to achieve optimal workability, was also employed in the previous study 5 . The cement-sand ratio was modi ed to 1:6 to…”

“…The current study focuses on concrete hollow block (CHB) masonry structures, commonly found in residential houses in developing countries 4 . However, CHBs exhibited limited compressive strength; for example, in the Philippines, CHBs have a weak compressive property, measuring 1 MPa 5 . Common failure behavior in masonry houses is out-of-plane wall failure, in-plane shear failure, and a combination of inplane or out-of-plane failure of walls, and roof collapse 6,7 .…”

“…Common failure behavior in masonry houses is out-of-plane wall failure, in-plane shear failure, and a combination of inplane or out-of-plane failure of walls, and roof collapse 6,7 . A shake table test was carried out on unreinforced masonry houses made of CHB, revealing that the gable wall was the weak element, ultimately leading to its collapse during the shaking 5 . Despite the building being reinforced, masonry walls often experienced heavy damage due to the low compressive strength of CHB.…”