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From page 545... ... 543 Steel girder bridges often use continuity over the interior supports to reduce interior forces on the spans. In continuous structures with composite concrete decks, the location of maximum negative bending moment is over the interior supports. Read the entire page →
From page 546... ... 544 DESiGN GUiDE FOR BRiDGES FOR SERviCE LiFE A.1. conStruction Procedure overview This section briefly describes the major steps in the construction procedure in order to establish a frame of reference and to introduce vocabulary used throughout the appendix. Read the entire page →
From page 547... ... 545 Appendix A DESiGN pROviSiONS FOR SELF-STRESSiNG SySTEM FOR BRiDGE AppLiCATiON WiTh EMphASiS ON pRECAST pANEL DECK SySTEM load is directed downward. Read the entire page →
From page 548... ... 546 DESiGN GUiDE FOR BRiDGES FOR SERviCE LiFE When the creep and shrinkage strains are known, or otherwise assumed, then LRFD specifications Section C4.6.6 can be used for calculating the resulting stresses and deformations. A.2.3 forces The forces and stresses in all components that arise as a result of the self-stressing construction procedure should be considered in evaluating the load effects during design. Read the entire page →
From page 549... ... 547 Appendix A DESiGN pROviSiONS FOR SELF-STRESSiNG SySTEM FOR BRiDGE AppLiCATiON WiTh EMphASiS ON pRECAST pANEL DECK SySTEM Minimum Final Prestress The recommended minimum level of prestress at the top fiber of the concrete deck over an interior support, after all losses, is 750 psi. Read the entire page →
From page 550... ... 548 DESiGN GUiDE FOR BRiDGES FOR SERviCE LiFE Equation A.1 gives the initial prestress at the top fiber that is to be applied: r1pi pf s σ σ ( ) Read the entire page →
From page 551... ... 549 Appendix A DESiGN pROviSiONS FOR SELF-STRESSiNG SySTEM FOR BRiDGE AppLiCATiON WiTh EMphASiS ON pRECAST pANEL DECK SySTEM For the structure shown in Figure A.2, this displacement (δ) Read the entire page →
From page 552... ... 550 DESiGN GUiDE FOR BRiDGES FOR SERviCE LiFE c. Using the force given by (b) Read the entire page →
From page 553... ... 551 Appendix A DESiGN pROviSiONS FOR SELF-STRESSiNG SySTEM FOR BRiDGE AppLiCATiON WiTh EMphASiS ON pRECAST pANEL DECK SySTEM where wsteel = uniform load due to self-weight of steel, wdeck = uniform load due to deck placement, d = deflection of support (positive upward) Read the entire page →
From page 554... ... 552 DESiGN GUiDE FOR BRiDGES FOR SERviCE LiFE d. Using the reduced force applied to the composite structure supported at the exterior supports, calculate the internal forces and stresses necessary for design. Read the entire page →
From page 555... ... 553 Appendix A DESiGN pROviSiONS FOR SELF-STRESSiNG SySTEM FOR BRiDGE AppLiCATiON WiTh EMphASiS ON pRECAST pANEL DECK SySTEM Composite Deflection Calculation of the deflection caused by the lowering of the interior support is determined by considering the composite bridge girder supported at the exterior supports only, as shown in Figure A.8. Read the entire page →
From page 556... ... 554 DESiGN GUiDE FOR BRiDGES FOR SERviCE LiFE The steps for calculating the deflected shape can be performed using the following steps, considering the structure supported at the exterior supports only, as shown in Figure A.10. L1 L2 Composite sh cr Figure A.9. Read the entire page →
From page 557... ... 555 Appendix A Read the entire page →
From page 558... ... 556 DESiGN GUiDE FOR BRiDGES FOR SERviCE LiFE A.4 deSign FLowchArt Figure A.12 provides a design criteria flowchart for the conventional design method and the self-stressing design method. Figure A.12. Read the entire page →
From page 559... ... 557 Appendix A DESiGN pROviSiONS FOR SELF-STRESSiNG SySTEM FOR BRiDGE AppLiCATiON WiTh EMphASiS ON pRECAST pANEL DECK SySTEM A.5 deSign AidS For two-SPAn bridgeS The following figures offer design aids for continuous beam two-span bridges. Read the entire page →
From page 560... ... 558 DESiGN GUiDE FOR BRiDGES FOR SERviCE LiFE Figure A.16. Continuous beam -- two unequal spans -- uniformly distributed load. Read the entire page →

From page 545...

... 543 Steel girder bridges often use continuity over the interior supports to reduce interior forces on the spans. In continuous structures with composite concrete decks, the location of maximum negative bending moment is over the interior supports.