Improving the accuracy of camber predictions for precast pretensioned concrete beams.

Details

• Creators:
  Honarvar, Ebadollah ; Nervig, James ; He, Wenjun ; Sritharan, Sri ; Rouse, Jon Matt
• Corporate Creators:
  Iowa State University. Bridge Engineering Center
• Corporate Contributors:
  Iowa. Highway Research Board
• Subject/TRT Terms:
  Accuracy Beams Creep Curvature Finite Element Method Precast Concrete Prestressed Concrete Shrinkage Thermal Analysis
• Publication/ Report Number:
  IHRB Project TR-625;InTrans Project 11-390
• Resource Type:
  Tech Report
• Geographical Coverage:
  Iowa
• Corporate Publisher:
  Iowa State University. Institute for Transportation
• Abstract:
  The discrepancies between the designed and measured camber of precast pretensioned concrete beams (PPCBs) observed by the
  
  Iowa DOT have created challenges in the field during bridge construction, causing construction delays and additional costs. This
  
  study was undertaken to systematically identify the potential sources of discrepancies between the designed and measured camber
  
  from release to time of erection and improve the accuracy of camber estimations in order to minimize the associated problems in
  
  the field.
  
  To successfully accomplish the project objectives, engineering properties, including creep and shrinkage, of three normal
  
  concrete and four high-performance concrete mix designs were characterized. In parallel, another task focused on identifying the
  
  instantaneous camber and the variables affecting the instantaneous camber and evaluated the corresponding impact of this factor
  
  using more than 100 PPCBs. Using a combination of finite element analyses and the time-step method, the long-term camber was
  
  estimated for 66 PPCBs, with due consideration given to creep and shrinkage of concrete, changes in support location and
  
  prestress force, and the thermal effects.
  
  Utilizing the outcomes of the project, suitable long-term camber multipliers were developed that account for the time-dependent
  
  behavior, including the thermal effects. It is shown that by using the recommended practice for the camber measurements
  
  together with the proposed multipliers, the accuracy of camber prediction will be greatly improved. Consequently, it is expected
  
  that future bridge projects in Iowa can minimize construction challenges resulting from large discrepancies between the designed
  
  and actual camber of PPCBs during construction.
  
  
• Format:
  PDF
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha-512:4986a6d9f4b9a99891301feb10edc4fd196f52975ae0c9c7fd295961763da0d40a8e2dea2e142ff9dd5b9bac1c65da3410c3ed84148ca443c20609f740c6461d
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/29403/dot_29403_DS1.pdf
• File Type:
  [PDF - 4.73 MB ]