ASSESSMENT OF STRENGTH PARAMETERS OF URM BLOCKS IN HERITAGE STRUCTURES IN THE PHILIPPINES

Unreinforced masonry (URM) heritage structures, because of their rudimentary building techniques, are vulnerable during extreme environmental events, particularly earthquake. Limited literature involving these structures provide challenges for sound engineering solutions in their preservation, considering their significance in a country’s history. Additional studies on the mechanical properties of masonry blocks – compressive, shear, flexural strengths, modulus of elasticity provide an insight on the behavior of structural components subjected to excessive loading conditions, and also establish parameters for seismic vulnerability assessments. The blocks considered are adobe, coralline limestone, and sandstone units, acquired from selected heritage structures in the country. Customized setups for shear and flexure tests were fabricated for lack of standard test methods. Results show that response of earth masonry to different load setup show monolithic behavior, distinct lack of elasticity, and intense deformability. Sandstone, while stronger in performance, exhibited very drastic failure mode in the form of sudden shear and chipping. Nevertheless, the masonry fabric proves to require further strengthening measures in resisting forces, as shown by their strength parameters. Furthermore, stress-strain properties of each sample show that sandstone, the type with greatest material strength, exhibited the smallest plastic deformation and abrupt failure, while adobe, the least average strength, exhibited the longest plastic deformation and gradual failure. Finally, a map is presented to show the spatial scatter of URM fabric used in heritage structures in the Philippines, the most common of which are coralline in Visayas and adobe and clay bricks in Luzon.