英文原文
A new way to design suspenders for through and half-through arch bridges
R.J. Jia ng, Y.Y.
Che n, Q.M. Wu, W.M. Gai and D.M. Pen gShe nzhen Mun ici pal Desig n
& Research In stitute, Shen zhe n, China
1 ABSTRACT
It is well-k nown that, i n through and half-through arch bridges, the sus pen ders are imp orta nt components since they connect the bridge deck to the arch ribs. The colla pse of bridge deck or arch ribs may be in duced once one or more sus pen ders are broke n. In this paper,the traditional design way of the suspendersin through and half-through arch bridges is discussed first. Based on the discussi on, a new way to desig n sus pen ders for arch bridges is the n put forward. The reas on ability of this new way is pro ved by nu merical an alysis exa mpl es. The impact effect of the remai ning components of the arch bridge due to the breakage of one or more suspenders is obtained by appropriate simulatio n using the comp rehe nsive commercial software ANSYS. It can be con cluded from the an alysis in this paper that the new way to desig n the sus pen ders for the through and half-through arch bridges can assure the safety of the bridge effectively eve n though one or more sus pen ders happen to break.
2 INTRODUCTION
With the rap id devel opment of new materials and con struct ion tech no logies, the modern arch bridges are now entering a new era. The span length of the modern arch bridges is in creas in g,a nd the first two Ion gest moder n arch bridges are the Chaotia nmen Yan gtse River Bridge and the Lu pu bridge, res pectively. The Chaotia nmen Yan gtse River Bridge built in 2008 is a tied steel truss arch bridge with a span len gth of 552m; and the Lupu Bridge built in 2003 is a steel box arch bridge with a cen tral span len gth of 550m. They are both half-through arch bridges and respectively located in Chongqing and Shan ghai, Chi na.Arch bridges can be classified into three categories accord ing to the relative po siti ons betwee n the deck and the arch: deck-arch bridge, half-through arch bridge and through arch bridge (Che ng J. et al. 2003). For both half-through arch bridge and through arch bridge, the sus pen ders are the imp orta nt components since they connect the bridge deck with arch
ribs and tran sfer kinds of loads from bridge deck to arches, and fin ally to foun datio n. However, at the same time they are the vuln erable members to be damagedor ruin ed, becausethey usually work both in formidable n atural en vir onment and un der fatigue-i nduced cycli ng loads (Li D.S.et al. 2007). It is a fact that the service life of the sus pen der is much shorter tha n that of the arch bridge, and the sus pen ders must be repl aced timely (Tang H.C. 2005).The damage to the bridge deck or arches may be in duced whe n one or more sus pen ders break, sometimes,eve n the colla pse of the arch bridge may happen. In recent years, the accidents of arch bridges' collapse caused severe casualties and huge econo mic loss (Li D.S.a nd Ou J.P. 2005 ). I n order to know well about the health con diti on of sus pen ders, kinds of realtime mon itori ng and diag no ses were con ducted (Li D.S. et al. 2007). However, both the tech no logies and the materials for structural health mon itori ng and diag nose are not fully devel oped up to now (Li H.N. et al. 2008)」n this paper, the traditional design way of suspendersin through and half-through arch bridges is discussed first. Based on the discussi on, a new way to desig n the sus pen ders in through and half-through moder n arch bridges is the n put forward. With the app licati on of this new way, the arch bridge will rema in safe eve n though one or more sus pen ders happen to break.This new desig n way is a differe nt method from the health mon itori ng to con trol the safety of the moder n arch bridges un der the con diti on that the break of the sus pen der is uncon trollable.The reas on ability and reliability of this new way is studied and pro ved by a nu merical an alysis exa mple based on a real through arch bridge. The impact effect of the remaining components of the arch bridge due to the breakage of one or more suspendersis obtained by appropriate simulation using the comprehensive commercial software ANSYS. It can be concluded from the analysis in this paper that the new way to desig n the sus pen ders in moder n arch bridges can assure the safety of the bridge effectively eve n though one or more sus pend ers happen to break.
3 DISCCUSION ON TRADITONAL DESIGN OF ARCH BRIDGE SUSPENDERS
For through-t ype and half-through-t ype arch bridges, the sus pen ders are an chored to arch ribs atone end and tran sverse beamsat the other. Gen erally sp eak ing, in the traditi onal arch bridge desig n the double-sus pen der an chorage (Fig.1) in stead of the sin gle-sus pen der an chorage is widely ado pted in order to kee p the arch bridge still safe and make the replacement of the suspenders more convenient when one suspender
happens to break.
勺6
Te
7
(b)
Figure 1 : Double-suspender anchorage
double-sus pen der an chorage,(b) In cli ned double-sus pen der an chorage
traditi on ally desig ned: (a) P arallel
However, the two sus pen ders at the same an chorage are usually desig ned as the same both in material and cross sect ions; i.e.,, E1=E2, A1=A2a nd 0 1= 0 2, where E, A and 0 are the elastic modulus, cross section area and inclined angles of the suspender, resp ectively. That means they have the same or similar stress and variati on of stress in service. They are also under the same or similar corrosion environment since they are located at the same an chorage. Hereby, it can be con cluded that the two sus pen ders at the same an chorage will fail at the same or similar time because of the almost equal level of both fatigue load and corrosi on en vir onmen t.Based on the discussi on above, it can be see n that the double-sus pen der system desig ned in the traditi onal way will not improve both the safety of the arch bridge and the convenience of suspenders replacement comp ared to the sin gle-sus pen der system.
4 A NEW WAY TO DESIGN ARCH BRIDGE SUS PENDERS
In order to kee p the remai ning structure of arch bridge still safe whe n one sus pen der happens to break, the double-sus pen ders must be desig ned with differe nt service life. The only way to achieve this aim is to desig n the two sus pen ders at the same an chorage with differe nt either material or cross sect ion areas since they carry the same fatigue loads and are un der the same corrosi on en vir onmen t.If the two sus pen ders at the same an chorage are designed with different materials, the extra in convenience both in design and con struct ion of the arch bridge will be in duced. The better way is to make the two
一种新的方式,通过和半透过拱桥设计吊带毕业论文外文翻译
