Experimental Investigation of Progressive Collapse of Prestressed Concrete Frames after the Loss of Middle Column

Table 1

Design parameters of the specimens.

Specimen	Span of frame beam (mm)	Clean span-to-depth ratio of frame beam	Initial effective prestress	Prestress action modes
S1	2600	12.0	N/A	N/A
S2	2300	10.5	0.6 fptk	Unbonded prestress
S3	2600	12.0	0.6 fptk	Unbonded prestress
S4	2900	13.5	0.6 fptk	Unbonded prestress
S5	2600	12.0	0.6 fptk	Bonded prestress