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OCR for page 92
92 "Final Strength" shown in the plans or as approved Materials by the Engineer. portland cement concrete for the precast bent cap and cap pocket fill; Testing of Cap Pocket Fill Concrete. Testing of the cap hydraulic cement (non-shrink) grout; pocket fill concrete is specified as follows: corrugated metal duct; lock seam, helical corrugated steel pipe; The compressive strength of the concrete for "Beam connection hardware; Setting Strength" and "Final Strength" shall be deter- Contractor submittal including a Precast Bent Cap Place- mined using concrete cylinders prepared and tested ment Plan; and in accordance with Article 8.5.7. The contractor shall prepare a minimum of six (6) cylinders per batch. Construction methods including grouting of grouted A Commercial Testing Laboratory approved by the duct connections and concreting of cap pocket connec- Engineer shall test the specimens for "Beam Setting tions (trial batch, placement, and material testing). Strength" and "Final Strength." Concrete failing to meet the minimum required compressive strength may be cause for rejection of the connection, concrete In addition, a grout specification for the grouted duct con- removal, and re-concreting of the connection by means nection from Matsumoto et al. (8) is presented. approved by the Engineer. The proposed addition to the AASHTO LRFD Bridge Construction Specifications, 2nd Edition, is as follows (35): Beam Placement Attachment CS1: Proposed Article 8.13.8--Special Require- Placement of beams on the precast bent cap is specified as ments for Precast Bent Cap Connections (AASHTO LRFD follows: Bridge Construction Specifications, 2nd Edition, 2004 with 20052009 Interims) The top surface of any precast bent cap anchorage shall New Article that adds specifications for precast bent cap be finished and waterproofed as shown in the plans. connections. Lifting loops shall be burned off 1 in below the sur- face of surrounding concrete and patched using material approved by the Engineer. 3.7 Example Connection Details Beams shall not be set until the grout for grouted duct connections or concrete for cap pocket connec- Based on test results and design and construction specifi- tions has reached a compressive strength equal to the cations, a set of example precast bent cap connection details "Beam Setting Strength" shown on the plans. have been prepared--three for the grouted duct connection (SDC A, SDC B, and SDCs B, C, and D), three for the cap 3.5.5 Measurement and Payment pocket connection (SDC A, SDC B, and SDCs B, C, and D), one for hybrid connection, and one for integral connection. Measurement and payment are specified as follows: To address the possibility that additional joint shear rein- forcement may be required for SDC B, two sets of details The measurement and payment processes used for are shown for the emulative connections related to SDC B: precast concrete members shall conform to the require- ments of Article 8.17. (1) SDC B: principal tensile stress, pt, less than 0.11 fc and (2) SDCs B, C, and D: principal tensile stress, pt, greater than or equal to 0.11 fc . Details similar to the SDC B example 3.6 Proposed Changes to AASHTO apply for SDCs C and D where additional joint reinforcement LRFD Bridge Construction is not required. Specifications The following drawings are provided as attachments to this Based on the work of Matsumoto et al. (8) and the results report: presented in this report, the proposed Article 8.13.8--Special Requirements for Precast Bent Cap Connections for the Attachment ECD1: SDC A--Grouted Duct Connection AASHTO LRFD Bridge Construction Specifications (35) has Example bent cap details for grouted duct connection in been prepared. This construction specification is provided as SDC A an attachment to this report. Attachment ECD2: SDC A--Cap Pocket Connection Major sections of the construction specification address Example bent cap details for cap pocket connection in the following: SDC A

OCR for page 92
93 Attachment ECD3: SDC B--Grouted Duct Connection Attachment ECD6: SDCs B, C, and D--Cap Pocket Example bent cap details for grouted duct connection in Connection SDC B (minimum joint reinforcement used) Example bent cap details for cap pocket connection Attachment ECD4: SDC B--Cap Pocket Connection in SDCs B, C, and D (additional joint reinforcement Example bent cap details for cap pocket connection in required) SDC B (minimum joint reinforcement used) Attachment ECD7: SDCs B, C, and D--Hybrid Connection Attachment ECD5: SDCs B, C, and D--Grouted Duct Example bent cap details for hybrid connection in SDCs Connection B, C, and D Example bent cap details for grouted duct connection Attachment ECD8: SDCs B, C, and D--Integral Connection in SDCs B, C, and D (additional joint reinforcement Example bent cap details for integral connection in SDCs required) B, C, and D