The designer of the project is solely responsible for the choice of the XCSH application as well as all structural design and calculations required by the codes of professional practice. The standard design and details presented in this manual and the available developed standard sheets require checking by the designer for the required and applicable loading conditions specific to each project location.
A wall type pier has been included in the plans as an example. The designer is solely responsible for the complete design of all foundation elements both piers and abutments , the piers and any non-standard abutments in accordance with the requirements of this manual and applicable AASHTO and other design specifications. The designer is also responsible to check the standard abutment and superstructure design for all loading and functional conditions specific to each project site.
The Designer is responsible to use Engineering judgment to verify no code changes since will affect the superstructure design. The mild conventional reinforcing is provided as a construction framework and for shrinkage and temperature effects. Unlike the 4. The abutment and post-tensioning detail plan sheets provide reinforcing details for these general zone requirements. Conceptually, two aspects may be mentioned here regarding the unique results of the design of XCSH bridges.
First, by design, the service HS truck will not introduce any tension into the bridge slab. The benefits of having a slab without flexural cracking at service level conditions for maintenance and durability are obvious. Second, because the controlling aspect of design is the tensile stresses in the slab due to service live loads, the structural system provides ample reserve flexural strength capacity compared to other superstructure systems RCSH, prestressed girder, steel girder, etc.
Therefore, the abutment and piers must be designed to replicate the assumed design condition. The additional displacements and rotations of the top of abutment piles, in particular, can be significant and must be accounted for in the design. The longer span configurations of XCSH, and more importantly, the foundation geology of a specific bridge site, impact this pile design.
The abutment vertical pile reactions for dead and live loadings are shown on the standard plans. The total superstructure vertical dead and live loads at the top of the piers are shown on the sample pier detail sheet to assist the designer in the design of the pier. Abutment Design The plan standards include a fully designed pile bent type abutment with pre-selected pile spacing and pile size.
A sample calculation is included in the Appendix for reference. The shortening of the slab at the abutments due to the combined effect of dead load, live load, post-tensioning, ambient temperature variations, and concrete creep and shrinkage is shown in Table A.
If the abutment foundation is too rigid to allow movement of slab at the abutment, the superstructure may not develop the assumed precompression, or the abutment foundations may behave undesirably. This concept will work for bridge sites where the geology is such that the piles have ample depth of fixity.
Additional measures may be needed based upon an analysis of the project site geology, especially where hard geology such as shale or rock strata is encountered close to the bottom of the abutment beam. Pre-drilled pile holes may be required in cases where hard subsurface soil conditions are encountered very close within 15 ft below the bottom of the abutment beam. The provision of the pre-drilled pile holes will allow the piles to accommodate the shortening of the slab at the abutment without exceeding pile capacity.
Pre-drilled holes for XCSH abutment piles typically extend a minimum of 10 ft below the bottom of the abutment beam. The diameter of the pre-drilled hole shall be such that a minimum 3 in clearance is provided all around the pile Fig. The backfill material shall meet current KDOT plans and specifications. Pre-drilled pile holes for XCSH are somewhat different than the conventional bid item of that name, in that they do not necessarily take place in rock, and they typically do not take place at the bottom of the pile, but at the top.
As an aside, these two factors should cause these pre-drilled pile holes to be more economical than conventional pre-drilled pile holes in rock. Example A. If the project site geology will not allow the pile that depth of fixity, then pre-drilled pile holes should be employed as appropriate.
Drilled shafts can be used at the abutments; however they must be designed to allow shortening of the slab to occur without significant restraint.
Alternatively, a semi-integral abutment could be employed. Either design is beyond the scope of this manual and should be performed entirely by the designer. Pier Design The design of the pier is similar to the substructure design of the abutment. The standards provide a plan detail for a sample wall type pier showing a typical connection detail between the slab and the pier beam.
However, when a single row of columns are used, the primary column reinforcement can be extended into the slab for the minimum embedment length required as per the code. Stop the web walls between the columns, 1 ft below the bottom of the slab.
For moderate to large column spacing, many XCSH bridges have been constructed with a separate pier cap, sitting immediately below the superstructure. This separate pier cap is conservatively designed to accommodate all the flexural and shear loadings neglecting the superstructure above.
Pre-drilled pile holes may be required when hard subsurface soil conditions are encountered very close to the bottom of the pier wall or the footing within 7 ft as per the discussion above in the case of the abutment design. Drilled shafts can be used at the piers; however, they must be designed to take into consideration the forces due to deformations of the slab.
This is usually more of a concern at the abutment than at the pier. It is imperative to use the spacing of the rail posts and the special reinforcing as shown on the XCSH standard plans in order to avoid conflicts of the post reinforcing steel with the post-tensioning.
The use of Type F4 concrete barrier will require further investigation to check potential conflicts with both transverse and longitudinal post-tensioning hardware. In any event, the profile of the longitudinal PT tendons should not change from the values shown in the plans. KDOT recommends the use of the approach pavement rest detail even if approach pavement is not used as in the case of rural dirt roads for sake of uniformity in construction as well as for a future paving option.
When required, use the KDOT standard approach slab details. XCSH bridges with skews are possible; up to 30 degrees have been built in the past. The structural design of the slab itself is not expected to change for the skew. However, the layout of the transverse post-tensioning and the corral rail post spacing will require modifications to the standard details to accommodate skews. This manual may be upgraded to include provisions for skews, depending on future needs.
Curves with very large radius should be feasible with required modifications of the standard plan details e. Extreme caution is required in the design of horizontally curved tendons. However, concepts and details to add additional interior spans need further investigation. At this point in time, it appears the limiting thermal unit length is dictated by the amount of allowable pile displacement taking place at the integral abutments. In some cases, it may be simpler to build an adjacent structure with a longitudinal joint, in order to avoid removing any of the existing XCSH.
All drawings are prepared in Microstation. It is imperative that the designers of XCSH are thoroughly familiar with the design theory and procedures as outlined in Section II prior to preparing construction plans, specifications and cost estimates.
The designers are urged to read this entire manual prior to the design and plan preparation of XCSH. Group I contains standards that are basically fully complete requiring only information regarding elevations, concrete type, designer notes, project number, title, sheet numbers, date, etc.
Group II are standards that are mostly complete except for requiring additional design information to be filled in such as quantities, project specific notes, substructure bar list and bending diagrams, etc. The designer is responsible to check all sheets, regardless of category, for accuracy and requirements as per applicable specifications, standards and site conditions for loads, geometry and function. The designer must thoroughly familiarize oneself regarding the details on the standards in Group I so all other sheets will have information and details consistent with and as required by the sheets in Group I.
Thus, D44SS2. Use KDOT latest naming conventions for sheet labeling. Obtain all CADD plan standards for the designation determined in step 1 ex. If not, perform the abutment design as per the procedure outlined in Section II. Use the example in the Appendix as a guide, if necessary. If non-standard abutment design is performed, use the format of the standard abutment plans to prepare the plans for the non-standard abutment design.
In most circumstances, the standard abutment design should be satisfactory. The designer should use appropriate pile type, size and number as needed by the site geology and check the design as required. Modify the example details and loads for the changed wall height.
Use the format of the sample plan detail sheet to prepare the actual pier detail sheet. Use the post spacing shown on Post-tensioning Details I sheet. Include the special post bar detail from the Post-tensioning Details II sheet, if applicable. Complete the sheet listing on the bridge index of sheet table. Review and modify the general notes as per site conditions and other related design items.
It is recommended that an engineer review and approve the slab elevation sheet prior to concrete placement. Step Typical Plan Sheets Include other typical plan and standard sheets. Please note that it is the responsibility of the designer to check the design of all pre- designed components of the plan standards used in the given project, as to its suitability for site conditions in terms of structural and functional design criteria.
There should be consistency between the information shown on the plans and any Project Specifications that may be used by the designer. Note that the Sika Grout PT will not be allowed due to recent discovery of chloride presence. Limits and method for calculating strand weights, as well as a breakdown of the transverse and longitudinal weights, is shown for information only on the General Notes sheet.
Based on XCSH bridges built in Kansas since , the following information is presented for certain items that are affected by post-tensioning: Item Unit Concrete, Grade 5. Full Record Other Related Research. Abstract SLAB is a computer model that simulates the atmospheric dispersion of denser-than-air releases.
Ermak, D L. United States: N. Copy to clipboard. United States. Other availability. The design principles of a solid slab bridge deck may be illustrated by the following illustrative example: Illustrative Example 1: Design a solid slab bridge superstructure having a clear span of metres and carriageway of metres with metres wide footway on either side for a National Highway.
Example on Design of Slab Bridge Design Data and Specifications Superstructure consists of 10m slab, 36m box girder and 10m T-girder all simply supported. Only the design of Slab Bridge will be used for illustration. Deck slab bridge 1. Purpose Of BridgePurpose Of Bridge A bridge is a structure providing passageA bridge is a structure providing passage over an obstacle without closing the wayover an obstacle without closing the way h.
Note: A 7 day wet cure is required on decks. This starts when the last curing protection is inplace. If control cylinders are used, there is a minimum of 96 hours. Note: Must be surface moist through the 7 day curing Size: 39KB. West made recommendations backed by carefully conducted experiments on the use of grillage analogy. He made suggestions towards geometrical layout of grillage beams to simulate a variety of concrete slab and pseudo-slab bridge decks, with illustrations.
Recommendations on the use of grillage analysis for slab and pseudo-slab bridge : Kasim H. Resan, Ismail Othman. Bridge deck slabs are one of the most exposed bridge parts and are often critical for the load carrying resistance. The existing procedures for structural assessment often under-estimate the capacity of bridge deck slabs Shu.
Consequently, it was important to examine the appropriateness of current analysis and design methods and. The term Deck Slab is mainly related to Bridge Engineering, where the slab acts as a deck or carraigeway for the vehicles to commute. Deck slab can be a both, solid and hollow. In case of a viaduct or flyover built with precast box girders with po.
Concrete Slab Bridges As with most modern bridge forms, the slab bridge hearkens back to precursors from the remote past. In the case of the slab, the origins are found in prehistory, as in the ancient "clapper" bridges of Dartmoor and Dartmeet, England Whitney. The form was subsequently abandoned at an early periodFile Size: KB.
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