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of initialization of structure, modeling uncertainties and so on.
Based on different performance levels according to probability model of earthquake occurrence, the
position of plastic hinges and the sequence of hinge formation are determined. One or some structural
members come to be inelastic to dissipate seismic energy, which should be provided with sufficient
ductility and not occur to spalling damage to resist large infrequent earthquakes. In the other hand,
performance-protected members and others that are inappropriate for dissipation of energy should be
always maintained in elastic response range. Consequently, the action on the columns and beams after
yielding should be paid enough attention to.
EXMAPLE
Model building
Function: Teaching building
Construction site: Design characteristic period of ground motion: 0.40 second.
Building type: Reinforced concrete frame (See Fig 1)
Number of stories: 4 and 6 stories Story height: 3.0m (all stories)
Number of spans: 3 spans Length between spans: 6.0m
The cross-section of columns:
450 x 500mm (side column at l~3 rd floor)
500 x 500mm (middle column at l~3 rd floor)
500 x 550mm (side column at 4-6* floor)
550x 550mm (middle column at 4~6th floor)
The grade of concrete: C35
The cross-section of beams:
Fig 1: Structure mode!
I l l
Fig 2: Plastic hinges formation
Ex. A: 250x 600mm,
Ex. B: 300x 500mm,
Ex. C: 250x600mm(side beams) and 250x500mm(middle beams)
Ex. D: 250x600mm(side beams) and 250x550mm(middle beams)
The grade of concrete: C25.
Performance objectives: Slight damage (earthquake probability of occupancy for the 20% in 50 years)
Middle scale damage (the 10% in 50 years)
Performance requirement:
Beam / Column moment: flexural cracks to remain small and no significant spalling should occur
Beam / Column shear: shear failure dose not occur and shear cracks are minor
Mechanism: weak beams / strong column mechanism
Analysis method: the static nonlinear analysis procedure using secant stiffness
Analysis result
Ex. A, B, C, and D is calculated and analyzed, whose position of plastic hinges is shown by Figure.2.