To investigate the post-fire seismic behaviour of reinforced concrete (RC) frames with different column-to-beam bending capacity ratios, four specimens were fabricated, which included a strong-beam-weak-column frame and a strong-column-weak-beam frame either under room temperature or after being exposed to fire. The fire test was conducted in a furnace chamber, followed by quasi-static tests under a low-frequency cyclic load. The crack patterns, hysteretic loops, plastic hinges, and failure modes were investigated in the loading process. The influence of two factors, i.e., the fire exposure and the column-to-beam bending capacity ratio, on the mechanical performance, ductility, stiffness degradation, and energy dissipation was compared and analysed. The experimental results indicated that the ultimate bearing capacity, the stiffness, the ductility factor, and the energy dissipation capacity of the RC frames decreased after fire exposure. The bearing capacity of the strong-beamweak-column frame decreased even more seriously. Although the yielding displacements of the post-fire frames increased, their ultimate displacements decreased. In addition, the strong-column-weak-beam frame under room temperature failed in the form of beam-end plastic hinging, while after being exposed to fire, the failure mode changed to shear-bond failure in column.
Reinforced concrete (RC) frame structures constructed prior to 1980s generally do not meet the requirements of seismic design code in mainland China due to the deficient design which only took gravity loads into consideration and ignored the lateral actions such as earthquake and winds. For instance, some old buildings were designed as
sub-standard RC frames with strong beams but weak columns, which might result in harmful brittle failures such as joint shearing and column hinging. In addition, building fire is one of the most frequent disasters that will happen in RC buildings. Although the post-fire RC frames can generally be retrofitted using proper strengthening techniques such as enlarging of joint area with newly cast concrete and fibre reinforced cementitious composites , adhesive bonding or near surface mouting of fibre reinforced polymers (FRP), bonding or anchoring of steel plates , etc.
Publisher : ELSEVIER
By : Ling-Zhi Li, Xin Liu, Jiang-Tao Yu, Zhou-Dao Lu, Mei-Ni Su, Jie-Hong Liao, Min Xia
File Information: English Language/ 13 Page / size: 2.56 MB
سال : 1397
ناشر : ELSEVIER
کاری از : لینگ ژی لی، چین لیو، جیانگ تائو یو، ژو دائو لو، مینی نی سو، جی هنگ لیائو، مین شیا
اطلاعات فایل : زبان انگلیسی / 13 صفحه / حجم : MB 2.56