Now that’s an earthshaking question. Picture Makati standing tall and proud amid a most vibrant skyline. How tall? Tall enough for its buildings to scrape and kiss the sky, it’s got some of the tallest structures in the Philippines.
The country’s commercial and financial center, Makati is home to over 25,000 business establishments that include banks, hotels, top corporations, insurance companies, embassies, and consultancies. Driving down Ayala Avenue on a clear day, I often find myself craning my neck and looking up at Makati’s skyscrapers with childlike wonder. I ask myself: How earthquake-proof are these behemoth buildings that tower at 50 to 70-plus stories high?
Yes, how safe and resilient are Makati’s buildings against strong earthquakes? What is the earthquake magnitude intensity of Makati’s current structures?
Engineer Marvin Caparros, consultant and CEO/president, R.S. Caparros & Associates, tells us, “The National Structural Code of the Philippines specifies that buildings and structures should be able to sustain a magnitude 7.0 earthquake at a minimum.”
Architect William Coscolluela, founder of WVC Coscolluela Architects & Associates, elaborates, “Before anything is built, property owners, their architects, and engineers have to comply with building regulations, including earthquake resilience. It is the LGUs’ (Local Government Units’) mandate to enforce compliance.”
MAKATI IS COMPLIANT
As far as Makati is concerned, Coscolluela adds, “Due to the strict enforcement of laws, Makati buildings are supposed to be compliant with the 7.0-magnitude minimum threshold. We cannot speak for the others, but all WV Coscolluela projects — such as the JG Summit Building, RCBC, Ayala Twin Towers, Zuellig Building, Greenbelt 1, Le Parc, Euro Villa, Palisades — meet that requirement.”
Because the Philippines is located along the Pacific Ring of Fire and thus prone to natural disasters such as earthquakes, is there a limit to the height of structures to be built in the Makati CBD (Central Business District)?
Caparros replies, “Based on the existing code, and to the best of my knowledge, there is no expressed cap or limit to the height of buildings that can be built in the country.”
During the earthquake last April 22, people were forced to use the stairs, some having to climb down from 40 to 50 floors and reporting sick the next day. Did you know that the 163-story Burj Khalifa in Dubai is the first high-rise building to use programmed elevators that allow controlled evacuations in case of emergencies? Does Makati have programmed elevators that can return to the lobby at the sound of the alarm or elevators dedicated to emergency personnel who can help people like the elderly, children, and the handicapped who are unable to take the stairs?
Caparros assures everyone, “With regard to elevators that automatically stop and go down to the lobby during earthquakes, this feature is already quite common, particularly for buildings located in the CBD. This feature is part of a building’s BMS (Building Management System).”
MANDATORY EARTHQUAKE INSURANCE?
Should mandatory earthquake insurance be practiced in the Philippines?
Caparros believes that it is useful but not necessary. “Besides the prohibitive cost, it is already the duty of the builders to ensure that our plan is up to code and has done the required earthquake analysis before construction to ensure that the structure won’t topple over in the event of a tremor.”
To which Coscolluela hastens to add, “Also, there is an existing law that requires structures built prior to 1992 to submit a Certification for Structural Soundness signed by an independent structural engineer. While 100-percent earthquake proof is not a guarantee, adhering to the structural code will mitigate more damage if we follow it.”
Following the killer 7.8 earthquake that ripped apart Baguio City, Cabanatuan City and Dagupan in 1990, leaving over 2,000 people dead, a crucial update was made on the structural code in 1992. The update improved standards for ductility of the whole structure. Ductility is “the ability of a structure to undergo large deformations while still keeping its capacity to carry its intended loads.” Likewise, it is “the ability of the structure to move and shake without breaking.”
Don’t be alarmed. All buildings sway during an earthquake as the energy of the quake’s waves moves beneath the ground. Like going with the flow. Thus, the stiffer shorter buildings, like a four-story one, are more vulnerable to damage than, say, a 40-story building.
FYI, the National Building Code of the Philippines, from which the structural code derives its mandate, was enacted by Congress in 1972, four years after a 7.3-magnitude temblor hit Casiguran, Quezon, also causing the collapse of the six-story Ruby Tower in Binondo. It is updated regularly by the Association of Structural Engineers in the Philippines (ASEP). Since 1972, the code has been updated six times.
The present code was written in an “ultimate strength basis,’ meaning “structures following the code should be able to withstand earthquakes with magnitudes 8 to 9 on the Richter scale,” says Cesar Pabalan of the National Institute of Civil Engineers.
So, does our building code prepare us for the Big One?
The code requires that a building’s “structural design must be resistant enough (resilient to seismic stress) to give its occupants enough time to evacuate.” It is designed to protect homeowners and building occupants as it prioritizes prevention of loss of lives over damage to property.
In the aftermath of the recent earthquakes, the Makati local government urged all building owners, administrators, and contractors to strictly observe safety precautions, such as ensuring that each building is equipped with a standby generator and emergency lights are strategically placed for rescue operations; all exits are passable at all times; all mechanical ventilation is in automatic mode, especially pressurization blowers and smoke evacuation fans; and that all elevators rest at the ground level.
With all these big moves, there should be little to fear or worry about when the Big One, God forbid, strikes.