醉歌离人M
y
=018f y A s(1-p)(h0-a0)+015N h(1-n0)+k A a f ay h
(1)
P
y
=
M
y
H
(2)
w here M
y
is the yield m om ent of the strengthened colum ns;
P
y
is the yield load of the strengthened colum ns;f
y
is the
yield strength of the longitudinal bars;A
s
is the area of the longitudinal bars;h0is the effective dep th of the colum n; a0is the dep th of concrete cover;p is the corrosion ratio of
the longitudinal bars;N is the axial load;n
is the axial
load ratio;n
=N/(f
c
bh);k is the effectiveness factor of the steel jacket.For the colum n strengthened only w ith steel jacketing,k=017,for the colum n strengthened both w ith CFRP and steel jacket,k=018;A a is the area of ten2
sile steel angle;f
ay
is the yield strength of the tensile steel angle,and H is the shear span of the colum n.
A ccording to Ref.[9],the m axi m um lateral loads P
m ax of the colum ns are calculated by
P
m ax
=(1124-0115ρ-015n0)P y(3) w hereρis the tension steel ratio,ρ=ρ1+ρ2,ρ1is the ten2 sion longitudinal steel ratio andρ2is the tension steel angle ratio.
The com parison bet w een test values w ith calculated val2 ues of the yield loads and the m axi m um lateral loads of the strengthened colum ns are show n in Tab16.In Tab16,P y t
and P
m ax t
are the test values of the yield loads and the m axi2
m um lateral loads of the colum n,respectively;P
yc
and
P
m axc
are the calculated values of the yield loads and the m axi m um lateral loads of the colum n,2a215a22f121dd36a32d82a62 paring the test values w ith the calculated values of the yield loads and the m axi m um lateral loads,it can be seen that the test results of the yield loads and the m axi m um lateral loads of the strengthened colum ns agree w ell w ith the correspond2 ing calculated values.
Tab16 C om parison of yield load and m axi m um lateral load
Speci m en P yt/kN P yc/kN P yc/P yt P m axt/kN P m axc/kN P m axc/P m axt
RBJ12122317122916011032531602681751106
RB J2222012123216611062651792661081100
RBJ22126516825812501973161452901900192
RBJ22225311425910711022911172911821100
RBJ22317214319911011152341312241460196
RBJ32126215727919011073341683021950191
RCJ2223015823916011042791622691890197
RCJ22127211426311201973201642961390192
015L i J inbo,and Gong J inxin
412 D uctility factor calculations of the strengthened speci2 m ens
D uctility factor is one of the m ost comm on param eters used for the seism ic evaluation of structural com ponents.In order to evaluate the perfor m ance of the colum ns under the current research,the disp lacem ent ductility factorsμΔof the strengthened colum ns are used.B ased on the test results, the disp lacem ent ductility factorsμΔof the strengthened col2 um ns are calculated by
μΔ=
1+20αwλw
01045+111n0
(4)
w hereαw is a factor rep resenting the type of hoops,αw= 110for square hoops;λw is the equivalent transverse rein2 forcem ent index for the confinem ent from steel hoops, w rapped CFRP and steel jacketing,and it can be exp ressed asλw=ρw1αf1+ν2ρw2αf2+ν3ρw3αf3.Hereρw1,ρw2andρw3 are the volum e ratios of stirrups,CFRP and batten p late to the confined concrete,respectively;αf1,αf2andαf3are the ratios of the yield strength of stirrups,the tensile strength of CFRP and the yield strength of batten p late to the equiv2 alent com p ressive strength of concrete f
c
,respectively.ν2 andν3are the effective confinem ent factors of CFRP and batten p late,respectively.ν2=εcf/εcu,εcf is the average CFRP strain in the p lastic hinge zone of the colum n at the ulti m ate lateral disp lacem entΔu,andεcu is the rup ture strain of CFRP.ν3=εaf/εau,εaf is the average strain of batten p late in the p lastic hinge zone of the colum n at the ulti m ate lateral disp lacem entΔu andεau is the strain of batten p late corresponding to the yield strength of batten p late.B ased on the test results,ν2=0145,ν3=0135.
Tab17show s the com parison bet w een the test values w ith the calculated values of the disp lacem ent ductility factors of the strengthened colum ns.In Tab17,μΔt andμΔc are the test disp lacem ent ductility factors and calculated disp lacem ent ductility factors of the strengthened colum ns,respectively. Com pared the calculated values w ith the test values of the disp lacem ent ductility factors in Tab17,it can be seen that,excep t for the speci m ens RBJ121and RBJ221,all the other calculated results are w ithin a17%error band.This error band scope is allow able for calculating the disp lace2 m ent ductility factor of strengthened colum ns.Thus,the calculated results confir m the ability of the p roposed calcu2 lation m ethod to p redict the disp lacem ent ductility factor of strengthened colum ns.
Tab17 C om parison of disp lacem ent ductility factor
Speci m enμΔtμΔc μ
Δc
-μΔt
μΔ
t
/%
RBJ12171511110647 RB J22615551999 RBJ221712971655 RBJ22210180910017 RBJ22311108719129 RBJ3216158516914 RCJ22613651917 RBJ22161477157175 C onclusions
The effectiveness of strengthening dam aged RC colum ns using com bined CFRP sheets and steel jacketing to i m p rove the seism ic perfor m ance of RC colum ns has been exam ined in this paper.B ased on the research results,the follow ing conclusions are derived:
1)The technique of strengthening corroded RC colum ns w ith com bined CFRP sheets and steel jacketing or w ith steel jacketing alone is quite effective,w hich significantly in2 creases the strength,ductility and energy absorp tion and dissipation capacities of the strengthened colum n,but strengthening a corroded RC colum n w ith com bined CFRP sheets and steel jacketing is m ore effective than strengthe2 ning only w ith steel jacketing in i m p roving the strength, ductility and energy absorp tion and dissipation capacities.
2)The degree of corrosion has a considerable influence on the behavior of the strengthened colum ns.The strength2 ening effects of the speci m en w ith a greater degree of corro2 sion in the ductility is better than those w ith a low er degree of corrosion.
3)Com pared the speci m ens strengthened w ith steel jack2 eting only and those strengthened w ith com bined CFRP and steel jacketing,the CFRP sheet w raps significantly i m p rove the seism ic behavior of the strengthened colum ns.
4)H igh axial load results in considerable reduction in the ductility of the strengthened colum ns.The strengthening effect of the colum ns under low axial load is low er in duc2 tility than that of the colum ns under high axial load.
5)The yield force,the m axi m um lateral load and the dis2 p lacem ent ductility factor of the strengthened colum ns can be calculated by the p roposed for m ulae in this paper.A good agreem ent bet w een calculated values and experi m ental results is observed.
References
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study on low2cycle behavior of corroded reinforced concrete m em ber under eccentric com p ression[J].J ourna l of B uild2 ing S tructures,2004,25(5):92-104.(in C hinese) [3]N iu D itao,C hen X inxiao,W ang X uem in.Experi m ental
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C hinese)
碳纤维布与钢构套复合加固锈蚀钢筋混凝土柱抗震性能研究
李金波 贡金鑫
(大连理工大学海岸和近海工程国家重点实验室,大连116024)
摘要:为改善锈蚀钢筋混凝土柱的抗震性能,利用碳纤维布与角钢对锈蚀柱进行复合抗震加固.试验共对12根试件进行了低周反复加载试验,研究参量包括钢筋锈蚀程度、轴向荷载、碳纤维布层数和角钢用量.试验结果表明,利用碳纤维布和角钢复合加固锈蚀柱可以显著改善锈蚀柱的承载能力、延性和耗能能力.复合加固后,加固柱的强度和延性与锈蚀柱相比,可分别提高019倍和1倍以上.基于试验结果,提出了计算加固构件屈服荷载、最大荷载和位移延性系数的简化公式,计算结果与试验结果极为吻合.
关键词:钢筋混凝土柱;抗震性能;锈蚀;加固;钢构套;纤维布;延性
中图分类号:TU37511
