【正文】 每根梁的跨中長期繞度在加載后每時每刻，都能被預(yù)測出來，實驗示數(shù)在這里被記錄。這些程序集中在混凝土徐變變形的標(biāo)準模型上，因此沒有考慮到環(huán)氧基樹脂的蠕變影響。當(dāng)與下面所討論和呈現(xiàn)的較平穩(wěn)的長期繞度曲線（圖5）相比，這一點尤其明顯。因為沒有任何原理適應(yīng)這種壓力的變化。這種荷載水平的目的是要使兩根梁達到工作的范圍。每根梁長3500mm，梁寬280mm，梁高180mm，從箱梁頂部至底部135mm位置處有4根縱向鋼筋（，單根面積100mm178。為了觀察鋼筋混凝土梁隨時間而發(fā)生的繞度，它的制作過程和實驗步驟都被呈現(xiàn)出來了。使用了兩種分析方法：一種是時程分析，另一種是有限元（FE）模型。 deflection。在玻璃鋼條的兩端的滑移也被監(jiān)測了。也就是說，假定梁的受拉面和玻璃鋼條之間是理想的約束和協(xié)調(diào)的應(yīng)變。已報道的實驗方案的目的是確認環(huán)氧樹脂蠕變的存在，而不是復(fù)制一個實用的改造方案。小心地把彈簧儀表的偏移尖端定位于碳纖維貼片暴露的末端。這是因為在截面彎矩不變的區(qū)域FRP條的張拉應(yīng)變保持不變。對于梁二的跨中繞度并不像梁一那樣被“清楚理解”。這份觀察報告與Choi et ，也證實了環(huán)氧基樹脂大部分蠕變發(fā)生在相對比較早的時期內(nèi)。開裂彎矩值的巨大差異凸顯了碳纖維貼片的加固效果。用源于梁一的最終徐變系數(shù)去分析梁二是一個有根據(jù)的設(shè)想，因為兩根梁是用同一批混凝土同時澆鑄而成，且在相同環(huán)境下進行加載實驗。兩種方法的目的都是為了評估梁的長期繞度受影響于混凝土的徐變和收縮。在徐變系數(shù)計算中用CEBFIP，當(dāng)相對濕度增加，徐變系數(shù)降低，意味在相對濕度大的時間段徐變增長率降低。碳纖維貼片顯著提高了梁二抗裂彎矩。荷載是通過懸掛混凝土塊于每根梁上表面。 MPa，該值是從直徑為100mm，高 200mm的圓柱測量而得，而這批圓柱是用澆筑梁的同一批混凝土澆筑而成。當(dāng)僅考慮混凝土蠕變時，從測量簡單梁的蠕變變形，不能預(yù)測有玻璃鋼條加固的梁的蠕變變形。一種普及的應(yīng)用，廣泛使用于實踐之中，那就是在普通鋼筋混凝土受拉面粘結(jié)玻璃鋼條以增加梁的抗彎能力。 reinforced concrete.INTRODUCTIONIn recent years there has been much research on the use of fiberreinforced polymers (FRPs) to strengthen existing concrete structures. One popular application, used widely in practice, is to bond FRP strips externally to the tension face of reinforced concrete (RC) beams to increase flexural capacity.The FRP strips are typically bonded directly to the prepared concrete surface using an epoxy adhesive. The strips may be anchored mechanically near their ends or supported by additional shear reinforcement, usually in the form of Ushaped FRP sheets. If the beam is subsequently loaded with sustained loads, creep in the epoxy adhesive could take place and would allow the FRP strips to unload, leaving them ineffective against the sustained load. Similarly, if the strips are prestressed as recently remended by some researchers (for example, Ye et ), creep in the epoxy may relieve some of the initial force. Hence, although the FRP strips can still assist in supporting additional live load, the increased sustained loads may exceed the capacity of what could effectively bee the original unstrengthened beam.Research into the timedependent behavior (creep and shrinkage) of concrete beams strengthened with externally bonded FRPs is scarce. Analytical models were verified against limited experimental observations of RC2 and timber3 beams externally reinforced with FRP strips. Similar approaches were used for a posite glass fiberreinforced polymer (GFRP) box girder with concrete in the pression flange and a carbon fiberreinforced polymer (CFRP) strip bonded to the tension In all of the aforementioned models, however, the effect of creep in the adhesive layer bonding the FRP to the tension face of the beams was neglected. That is, perfect bond and strain patibility was assumed between the substrate and the FRP. Recent experiments by Choi et demonstrated that significant creep under shear stresses occurs in the epoxy at the concreteFRP interfaces when loading is applied within 7 days of epoxy application.Herein, the results of an experimental investigation and acpanying analytical predictions of immediate and timedependent beam deflections are described. The construction of the RC beams and the experimental program for observing their timedependent deflection are presented. The measured deflections are pared to deflection predictions using the ACI and CEBFIP methods implemented according to the remendations of Hall and The longterm deflection data show that the timedependent (creep) deformation of the CFRPstrengthened beam is a larger proportion of its immediate deformation than the same deformation ratio for the unstrengthened beam. The creep of the beam with the FRP strips could not be predicted from the creep measured on the plain beam when creep of concrete alone was considered. Because CFRPs have not been observed to creep at the stress levels generated,7,8 the additional creep may have occurred in the epoxy adhesive bonding the FRP strips to the concrete.The creep mechanism is expected to be a simple flow of the epoxy under the shear stress,5 which develops to create tension in the FRP strip. While models exist for predicting longterm deformation of RC beams strengthened with FRP (for example, Charkas et ), these models do not account explicitly for creep of epoxy adhesives. Herein, we use two different approaches to determine if creep in the epoxy can account for the different behaviors observed in the beams: a stepbystep intime analysis allowing incremental creep of concrete and epoxy in each time step and enforcing equilibrium at the end of the time step, and finite element (FE) modeling with shear flow allowed in the epoxy adhesive layer.RESEARCH SIGNIFICANCEThe potential effects of creep on RC beams strengthened with externally applied FR