BAGUIO CITY – The Philippine Institute of Civil Engineers (PICE) Baguio City Chapter ruled that the burned structures of the city public market, particularly Blocks 3 and 4, can already be classified as hazardous and critical following the 5-hour fire that gutted the market structures last March 11-12, 2023.
PICE Baguio City chapter president Engr. Richard Carulla Pascua pointed out that the hazardous section of the burned structures includes the severe warping of steel decking, debonding of concrete slab from steel decking, honeycombs on concrete beams and columns and surface cracks while the critical section is the one with slight to moderate warping of steel decking, probable debonding of concrete slab and steel decking at moderate warping, honeycombs on structural members and surface cracks.
The PICE Baguio chapter recommended that for the hazardous section, on a short term, the local government must immediately brace the underside of the warped decking with W6 x 9 steel sections or any equivalent bracing system to stabilize long-term instantaneous deflection.
However, Pascua underscored that slab cannot be used for the aforesaid proposed intervention that should be immediately undertaken in the identified hazardous section within the burned area.
Moreover, the group recommended to the city that it also must undertake a random plate-load test to validate actual load carrying capacity and conduct a random core test to validate concrete strength vis-à-vis the presence of honeycombing that could have been continuous through the core of the structural element.
The PICE also underscored that the city must also provide a cover for the slab to discourage trespassing, and most importantly to prevent ponding from water seepage and increasing the dead load on the slab aside from continuous monitoring of the structure for residual deformation.
The PICE asserted that there should be no occupancy that should be done in the burned area of the city public market until further tests that will confirm structural integrity of the burned structures.
In the long-term, Pascual explained that the slab system may have to be demolished and replaced for safety purposes.
On the other hand, the expert emphasized that on the critical section, in a short term, limited occupancy should be adopted until further tests will confirm structural integrity aside from the fact that steel decking with significant warping should be braced with W6x9 steel sections at mid-span or 3 end points depending on the extent of warping.
Pascual said that the city should also conduct a random plate-road test to validate actual load carrying capacity conduct a random core test to validate concrete strength vis-à-vis the presence of honeycombing that could have been continuous through the core of the structural element; provide a cover for the slab to discourage trespassing and most importantly, to prevent ponding from water seepage and increasing the dead load on the slab and continuous monitoring of the structure for residual information.
He emphasized that in both cases, the concerned market structure should be continuously monitored for any residual deformation that could occur through time. The plate-road test and core test could be conducted to confirm structural integrity.
The PICE structural committee offered its services to the local government to supervise the testing of structural elements and to update the city of the implications of the results of the proposed testing.
In the short term, the experts asserted that limited occupancy should be observed for the critical section while no occupancy should be enforced in the identified hazardous section until the tests on the decking shall have been completed and validated as to structural safety.
In the long term, Pascua proposed that the floor system at the identified moderate to severe warping may have to be demolished and replaced.
Earlier, the test conducted by the BIP Steadfast Ground Inc. on the burned structure to determine its strength and stability had shown that the building is structurally sound and can withstand the stresses and strains of daily use. Contributed article