铁道学报
鐵道學報
철도학보
2014年
4期
76-85
,共10页
剩余静载承载力%重载铁路%预应力混凝土梁%疲劳试验%疲劳损伤
剩餘靜載承載力%重載鐵路%預應力混凝土樑%疲勞試驗%疲勞損傷
잉여정재승재력%중재철로%예응력혼응토량%피로시험%피로손상
post-cyclic-loading residual static bearing capacity%heavy-haul railway%PC beam%fatigue test%fa-tigue damage
基于应变和振幅的疲劳试验实时测试系统，通过10片1/6缩尺模型梁疲劳试验，研究重载铁路桥梁疲劳后静载破坏形态以及振幅、刚度、非预应力筋和预应力筋应变、混凝土应变随反复荷载次数的变化规律。研究表明：重载铁路32 m预应力混凝土梁疲劳后剩余静载承载力演变呈现“Z”字形三折线的3个阶段，即基本不变阶段、直线下降阶段和压弯失稳破坏阶段。第一阶段，疲劳后试件静载破坏形态与普通静载破坏形态相同，试件静载承载力基本保持不变；第二阶段，试件静载承载力直线下降，直至压弯失稳破坏，最终梁的剩余静载承载力降至原有承载力的50％～60％，主要由预应力筋提供。与普通静载破坏试验相比，疲劳后静载破坏试验不同的地方主要表现在混凝土、梁底普通钢筋和预应力筋等材料的应力-应变本构关系上，受压区混凝土残余应变不断增加，变形模量降低了20％～30％，普通钢筋和预应力筋残余应变也明显增加，但弹性模量和屈服强度（预应力筋极限强度）基本不变。
基于應變和振幅的疲勞試驗實時測試繫統，通過10片1/6縮呎模型樑疲勞試驗，研究重載鐵路橋樑疲勞後靜載破壞形態以及振幅、剛度、非預應力觔和預應力觔應變、混凝土應變隨反複荷載次數的變化規律。研究錶明：重載鐵路32 m預應力混凝土樑疲勞後剩餘靜載承載力縯變呈現“Z”字形三摺線的3箇階段，即基本不變階段、直線下降階段和壓彎失穩破壞階段。第一階段，疲勞後試件靜載破壞形態與普通靜載破壞形態相同，試件靜載承載力基本保持不變；第二階段，試件靜載承載力直線下降，直至壓彎失穩破壞，最終樑的剩餘靜載承載力降至原有承載力的50％～60％，主要由預應力觔提供。與普通靜載破壞試驗相比，疲勞後靜載破壞試驗不同的地方主要錶現在混凝土、樑底普通鋼觔和預應力觔等材料的應力-應變本構關繫上，受壓區混凝土殘餘應變不斷增加，變形模量降低瞭20％～30％，普通鋼觔和預應力觔殘餘應變也明顯增加，但彈性模量和屈服彊度（預應力觔極限彊度）基本不變。
기우응변화진폭적피로시험실시측시계통，통과10편1/6축척모형량피로시험，연구중재철로교량피로후정재파배형태이급진폭、강도、비예응력근화예응력근응변、혼응토응변수반복하재차수적변화규률。연구표명：중재철로32 m예응력혼응토량피로후잉여정재승재력연변정현“Z”자형삼절선적3개계단，즉기본불변계단、직선하강계단화압만실은파배계단。제일계단，피로후시건정재파배형태여보통정재파배형태상동，시건정재승재력기본보지불변；제이계단，시건정재승재력직선하강，직지압만실은파배，최종량적잉여정재승재력강지원유승재력적50％～60％，주요유예응력근제공。여보통정재파배시험상비，피로후정재파배시험불동적지방주요표현재혼응토、량저보통강근화예응력근등재료적응력-응변본구관계상，수압구혼응토잔여응변불단증가，변형모량강저료20％～30％，보통강근화예응력근잔여응변야명현증가，단탄성모량화굴복강도（예응력근겁한강도）기본불변。
A real-time railway bridge fatigue test system was built for measurement of beam strains and vibration amplitudes .The fatigue test of a total of 10 1/6 reduced-scale PC model beams of heavy-haul railway bridges was made to study the development of static and post-cyclic-loading failure patterns and the changing law of vertical beam vibration amplitudes ,stiffness ,strains of non-prestressed and prestressed reinforcing bars and concrete strains with the frequency of repeated cyclic loading .Test results indicate as follows :Evolution of the post-cyclic-loading residual static bearing capacity of 32m-span PC beams of heavy-haul railway bridges is fea-tured by the Z-shaped curve ,w hich undergoes three stages ,i .e .,the basically unchanging stage ,the straight-line falling stage and the bending failure stage .In the first stage ,the post-cyclic-loading static failure pattern is the same with the ordinary failure pattern of a specimen under static loads ,the static bearing capacity of the specimen remains basically unchanged .In the second stage ,the static bearing capacity of the specimen declines in the straight-line manner until buckled to failure and the residual static bearing capacity is reduced to 50% ~60% of the original bearing capacity ,which is provided largely by prestressed tendons .In comparison with the ordinary static failure tests ,the difference of the post-cyclic-loading static failure tests largely lies in the consti-tutive stress-strain relationship of the materials of concrete ,ordinary beam-bottom bars and prestresed bars and so on .After fatigue loading ,the residual concrete strains in the compression zone reep on going up and up and the deformation modulus gets dow n by 20% ~30% ;at the same time ,the residual strains of prestressed and non-prestressed steel bars increase obviously ,but the elastic modulus and yield strength (the ultimate strength of prestressing steel bar ) remain basically unchanged .
