Decisive for  Ibe award decision was hence not only  Ibe offered price but even  to a higher degree Ibe form and functionality of  Ibe structure. Often conflicting aspects of  architectural demands and effective construction costs had to be combined to one optimum overall concept to be successful in Ibe bidding process. The particular wish of  Ibe population not to sacrifice design and environment to infra-structural needs of  Ibe bridge was taken into account. Awarding of design and execution of  a construction project in Ibe framework of  a de-sign and build process to one and Ibe same contractor allows an optimum solution refiectiog inpidual public  interests,  and incorporates  Ibe construction companies' know-how about construction execution early on in Ibe project. The bidding companies, designers and archi-tects are given Ibe opportunity to concentrate not on Ibe price but on an idea competition in view of  highest functiona1ity,  economic efficiency and sustainability. Design and built means that the client is not the interface between designer and contrac-tor of  the construction services with all the well-known risks in  tenDs of  time and  finances. The awarding procedure gives  the client  the opportunity to hand over  the overall respon-sibility for design. cost calculation and construction execution  to the contractor and provides him, alongside highest possible cost and schedule reliability, with a structure tailored to his wishes.
3.  Design of Load-Bearing Structure In close dialogue with  the  design  and build team,  architect Paul Wmtermans  created the design, which plans a slender, :flowing  load-bearing structure  :intended to integrate itself  mod-estly into the  flat Dutch landscape.  'Monuments' that highlight themselves and relegate their surroundings to the background were quickly dismissed. --qs 2  52$?  $  r:= , Figure 1:  View of  the structure ' I'~  ...  ,- I ] J  I ~ 0...-. -' .  ~ , ,  , ~.J~~  _____ 0  __________________________ __ _ _ Figure 2:  2 Ground plan of  the structure I~ = -:-- .. .:~ -- -- ---l _"'o  .. A truss-arch above  the river followed almost conclusively. The arch's milrimum. span width was set at 150m in  the project requ:irements.  To  reduce:  the  construction height  the arch's form was designed as continuous system. over the 75m wide neighboming spans. The result was a rise of  the arch of 14.5m, only amounting to  I:  10.3  in relation to the width of the main span. For design reasons, the outside surfaces and  the bottom. views of  the main girders are in-clined by 10 degrees and 6.5 degrees respectively. Architectural aspects led  to a 10 degree in-clination of  the truss-arches to the inside as even  continuation of  the outer webs' inclination. Keeping the regular clearances for railway traffic compelled to a continuous widening of  the  truss's lower chords as  the arch height rises because the inside edge of  these hollow box girders, just as  the ballast borders and cable ducts, have to run with a constant distance to the track. axis. For architectural reasons there are no connections or cross beams between  the arches. Maximum t:ranspa.rency  in the bridge's front view required a minimisation of  the mun-her of  diagonals in the truss arch. Structural considerations and  the fact that further reducing the diagonals would have been uneconomic due to the significantly increased need of  struc-tural steel, limited the node distances to 30m. The  foreland  areas had to be spanned by a main load-bearing structure as  slender as possible with a constant construction height. The structural height of  the bridge's main girder was very limited anyway by the alignment of  the railway line's gradient and the clearance between the Ijssel and  the road at Gelderse Dijk. As  lower longitudinal girders arranged  below  the track: installations would have entailed ridiculously short distances between bearings, the main girders were arranged on  the sides of the track. In  consideration of  design prescriptions, 2.6Om construction height was determined for the main girder,lowered at some points to 1.95m above the road at Gelderse Dijk. The decision. influenced by architecture and construction operation" for uniform materi-als, and the  implementation ofthc main load-bearing structure in steel, led to the choice of regular span widths of  40m and shorter edge spans for the foreland areas. The slenderness of the longitwlinal girders is with 1:  15.4 a  technically and economically advantageous value for a  railway bridge, the span length of  40m is beneficial for fabrication and assembly. Another design featme was not  to integrate the  foot and cycle path into the mam cross section of  the bridge which would have made it more massive. Attached on the side of  the railway superstructure it is intended to be carried by  the later as optically independent cross-ing structure. The  flat 1atcral views  of  the  longitudinal girders at railing height as well as  the lower edge of  the foot and cycle path were inclined according to the design of  the mam cross sec-tion. In  the design. the substructures were V-shapcd piles optically  inconspicuous underneath the load-bearing structure and adapting to the surrounding with their concrete colour, high-lighting the red superstructure as  the main load-bearing structure crossing the river. In the  design of  the  load-bearing  structure and the bearings  system,  aspects  of  the  load-bearing structure itself  and  the track superstructure had  to be weight up against each other. To minimise maintenance works on the load-bearing structure  and the superstructure, the decision's premise was to keep the number of  bearings and  joint as small as possible. Accord:ingly a load-bearing structure continuous over  the whole length of927m without joints was designed Expansion  joints were restricted to  the superstructure's end. Decisive criteria were also that around 100m from the bridge's end in Hattem. switches had to be in-stalled on  the superstructure and  that the bridge was in a bend  in some areas. With  the present design prescriptions and  regarding the length of  the bridge, a complete elimination ofrail expansion  joints was not feasible. However, it was possible to limit them to one expansion joint in the  radial 1rack at the abutment Zwolle. On the  side of Hattcm the superstructure together with the cycle path construction was connected to the abutment because of  high horizontal bearing forces, and as well as the expansion  joint, a difficult and necessarily replaceable bridge bearing was eliminated. High-quality rail expansion  joints with large elongation at the end of  long bridges are not to be assessed disadvantageously in view of  serviceability, maintenance and repair com-pared to a high number of  small transitions. On the contrary standard transitions of  simpler design show weaknesses of  unguided areas of  the rail entailing excessive wear, higher main-tenance works and more noise. The shear-resistant connection of  the cycle path on the side, acting in  conjunction with the whole cross section, meant  that high yet manageable stresses on  the bridge consoles were to be expected. A regular distribution of  joints was however dismissed because of  the struc-tural di:fficulty, susceptibility  to damage and maintenance efforts as well  as  the architcctura11y desired even and undisturbed visible smfaccs. 铁路桥英文文献和中文翻译(2):http://www.youerw.com/fanyi/lunwen_32979.html