Calibration of AASHTO LRFD Concrete Bridge Design Specifications for Serviceability (2014) / Chapter Skim
Currently Skimming:
Pages 140-145
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 140... ...
6 PROPOSED CHANGES TO AASHTO LRFD Various articles of AASHTO LRFD which would need to be modified to implement the calibrated SLS resulting from this research were identified. This Chapter contains the suggested modifications formatted in a form suitable for consideration by the affected Technical Committees as potential Agenda Items for the Highway Subcommittee on Bridges and Structures (HSCOBS)
|
From page 141... ...
6.2 Cracking of Prestressed Concrete 6.2.1 Proposed Revisions to Section 3 3.4 -- LOAD FACTORS AND COMBINATIONS 3.4.1 -- Load Factors and Load Combinations The total factored force effect shall ……. Service I -- Load combination relating to the normal operational use of the bridge with a 55 mph wind and all loads taken at their nominal values.
|
From page 142... ...
Service IV -- Load combination relating only to tension in prestressed concrete columns with the objective of crack control. components designed using the currently-specified methods for instantaneous prestressing losses and the currently-specified Refined Estimates of TimeDependent Losses method, an increase in the load factor for live load from 0.8 to 1.0 was required to maintain the level of reliability against cracking of prestressed concrete components inherent in the system.
|
From page 143... ...
Table 3.4.1-1 -- Load Combinations and Load Factors Load Combination Limit State DC DD DW EH EV ES EL PS CR SH LL IM CE BR PL LS WA WS WL FR TU TG SE Use One of These at a Time EQ BL IC CT CV Strength I (unless noted) γp 1.75 1.00 -- -- 1.00 0.50/1.20 γTG γSE -- -- -- -- -- Strength II γp 1.35 1.00 -- -- 1.00 0.50/1.20 γTG γSE -- -- -- -- -- Strength III γp -- 1.00 1.4 0 -- 1.00 0.50/1.20 γTG γSE -- -- -- -- -- Strength IV γp -- 1.00 -- -- 1.00 0.50/1.20 -- -- -- -- -- -- -- Strength V γp 1.35 1.00 0.4 0 1.0 1.00 0.50/1.20 γTG γSE -- -- -- -- -- Extreme Event I γp γEQ 1.00 -- -- 1.00 -- -- -- 1.00 -- -- -- -- Extreme Event II γp 0.50 1.00 -- -- 1.00 -- -- -- -- 1.00 1.00 1.00 1.00 Service I 1.00 1.00 1.00 0.3 0 1.0 1.00 1.00/1.20 γTG γSE -- -- -- -- -- Service II 1.00 1.30 1.00 -- -- 1.00 1.00/1.20 -- -- -- -- -- -- -- Service III 1.00 0.80 γLL 1.00 -- -- 1.00 1.00/1.20 γTG γSE -- -- -- -- -- Service IV 1.00 -- 1.00 0.7 0 -- 1.00 1.00/1.20 -- 1.0 -- -- -- -- -- Fatigue I -- LL, IM & CE only -- 1.50 -- -- -- -- -- -- -- -- -- -- -- -- Fatigue II -- LL, IM & CE only -- 0.75 -- -- -- -- -- -- -- -- -- -- -- -- Table 3.4.1-4 -- Load Factors for Live Load for Service III Load Combination, γLL Component γLL Prestressed concrete components designed using a refined time step method to determine the time-dependent prestressing losses in conjunction with the gross section properties and without taking advantage of the elastic gain 0.8 All other prestressed concrete components 1.0 141
|
From page 144... ...
6.3 Fatigue Only Fatigue I Limit State is applicable to concrete and reinforcement. Information on the Fatigue II Limit state is included for reference and they were based on work done on steel components by Kulicki et al.
|
From page 145... ...
6.3.2 Proposed Revisions to Section 5 5.5.3.2 -- Reinforcing Bars The constant-amplitude fatigue threshold, (ΔF) TH, for straight reinforcement and welded wire reinforcement without a cross weld in the high-stress region shall be taken as: ( )
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.