January 26, 2015Dr. John ManderChief EngineerDepartment of TransportationDear Dr.Mander,In response to your current need regarding the design of a 900ft bridge, BridgeLink is interested in offering our professional service. BridgeLink is a team of five Structural Engineers with a turnover of over USD 1,300,000. We are recognized for team-building, creative problem solving and high degree of expertise in the bridge engineering field. Counting with the experience of our team members, we are confident to fulfill this challenge.The following five proposals have been suggested:1. Segmental Construction with Pre Tension + Dywidag system + Post Tension 2. Segmental with Pre Tension + Post-tensioning.3. Solid Slab 900 Ft Bridge (Pre Tension)4. I-Girder + Segmental 900 FT Bridge5. Monolithic Prestressed Concrete BridgeFeel free to evaluate each of the proposals. I hope that you will not hesitate to call or email us for any questions.Yours Sincerely,BridgeLink Consulting Services.Enclosure: Proposals with technical drawings.

Design Option 1: Segmental Construction with Pre Tension + Dywidag system + Post Tension All the spans of the bridge would be segmented in this case with segment lengths ranging from 10 ft. to 40. Ft The envisaged cross section of the segments would be box girder. The envisaged launching method is incremental launching method. RCC design would be adopted for Piers and Pier Caps All the segments would be precast and pre-tensioned in order to counteract the stresses induced due to erection. The 140 ft. spans would comprise of segments 30ft-40ft-40ft-30ft. The 190 ft. spans would comprise of segments 15ft-40ft-40ft-40ft-40ft-115ft. The 240 ft. span would comprise of 6 segments each of length 40 ft. While erecting the segments each segment would be connected with dywidag bars from one end of the span. Finally each span would be post-tensioned using the load balancing concept.

Design Option 2: Segmental with Incremental Post-tensioning All the spans of the bridge would be segmented in this case with segment lengths ranging from 10 ft. to 40. Ft The envisaged cross section of the segments would be box girder. The envisaged launching method is incremental launching method. RCC design would be adopted for Piers and Pier Caps All the segments would be precast and pre-tensioned in order to counteract the stresses induced due to erection. The 140 ft. spans would comprise of segments 10ft-20ft-40ft-40ft-20ft-10ft. The 190 ft. spans would comprise of segments 15ft-40ft-40ft-40ft-40ft-115ft. The 240 ft. span would comprise of 6 segments each of length 40 ft. In this case each segment would be connected using post-tensioned cables. The post-tensioning will Each span would be post-tensioned using the load balancing concept.

Design Option 3: SOLID SLAB 900 FT BRIDGE (PSC) Simply supported spans, connected by four piers. The end spans have a length of 140 ft, the middle span has a length of 240 ft., and the remaining two are 190 ft. Pretension 140 ft. I-girder (x2). Constant eccentricity. Steel frames placed between the piers separated every 10 ft to support the casting of the slab. This system will be removed after construction is finished. Before the casting of the concrete, the pre-tensioned cables are set in place. Superstructure is comprised of a pre-tensioned concrete slab, supported at it ends. Substructure would comprise of RCC Piers and Pier caps. Height of the cross section is determined by the longest span length, the following expression is used.

Design Option 4: I-Girder + Segmental 900 FT Bridge (Prestressed concrete)

Simply supported spans, connected by four piers. The end spans have a length of 140 ft, the middle span has a length of 240 ft, and the remaining two are 190 ft Pretension 140 ft I-girder (x2). Constant eccentricity. Segmented 40 ft box girder sections. Starting from middle pier and advancing simultaneously on both sides. Pretensioned for erection stresses. While erecting the segments each segment would be connected with dywidag bars from one end of the span. Posttensioning matching the moment diagram is used to balance the dead load of the structure. Also used to reduce deflections on the spans and crack propagation.

Design Option 5: Design of Monolithic Prestressed Concrete Bridge This type of bridge consists design of I-girders that are spliced. End Spans are 140ft in length. Remaining span consists of 2 I-girders of length 100ft, 2 I-girders of length 90ft and 2 I-girders of length 120ft. All the girders are spliced and each span is post-tensioned separately. Deck slab is casted and post-tensioning is run through the whole bridge to take care of the live load and prevent cracks in the structure. Pier cap are of square cross-section and length is around 5ft. Pier columns are designed as prestressed columns to prevent cracking and buckling. Compare the design with unshored bearing design.

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