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Taiwan Earthquake 2016

posted Feb 21, 2016, 1:59 AM by jeffery jim   [ updated Jul 7, 2016, 10:22 AM ]
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The collapsed of 17-story building at Taiwan (due to earthquake with magnitude 6.4 at 03:57 at Southeast Taiwan on February 6, 2016) which was said to be build with concrete, rebars and some oil-cans. This left 115 people dead with more than 500 others injured. Before one jumps into conclusion that the structure was effected by such workmanship or indespicable act, you have to understand the function of those cans and view the orientation of the building after the collapse.

During the construction of waffle slab (quite normal in 70s Malaysia Government buildings), the use of these cans is no other than just spacers between the rib beams and simply supported slab. Instead of using hollow brick which is much heavier, unconventionally, the builder might have chose the use of cans. This have no significant effects on the beam/slab design since it was designed to propagate stresses and loadings through thin (but many) sections of secondary rib-beams to the primary beam. If these cans were applied to columns, it is functioning as encasement to the concrete structure for aesthetic purposes. What is important is the As' or steel area desired to withstand vertical stress.


          
    

    

The collapsed structure most likely have a very soft foundation or ground/bearing. From tale-tell signs, pillars buckled in a typical fashion when undergo seismic forces.The structure failed due to its capability to resist sway and motion when experiencing aftershock at t0.2s.

The subsequent failure is due to the design selection, where the design engineer (consultant) failed to consider the rigidness, robustness and ductility of the slab. When the slab failed to provide shear resistance (through beams and slabs) to displaced columns, eventually the building no longer in equilibrium and therefore lapse the design envelope and fail.

The government and local authority should be responsible as well for not warrant retro-fitting works post 1999 earthquake. Did our Local Authorities in Malaysia came out with such recommendations? No. Should they start to warrant retro-fitting works? It is about time when most buildings reached their 30-50 years old serviceability life span.




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