Improving the Accuracy of Camber Predictions for Precast Pretensioned Concrete Beams, TR-625, 2015

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.

Iowa 100% E News, February 2001, Vol.1, no.1

Newsletter for Information Technology Department

Iowa 100% E News, March 2001, Vol.1, no.2

Newsletter for Information Technology Department

Iowa 100% E News, April 2001, Vol.1, no.3

Newsletter for Information Technology Department

Iowa 100% E News, May/June 2001, Vol.1, no.4

Newsletter for Information Technology Department

Iowa 100% E News, July/August 2001, Vol.1, no.5

Newsletter for Information Technology Department

Iowa 100% E News, August/September 2001, Vol.1, no.6

Newsletter for Information Technology Department

Iowa 100% E News, December 2001, Vol.1 no.8

Newsletter for Information Technology Department

Iowa 100% E News, March 2002, Vol.2, no.3

Newsletter for the Information Technology Department

Iowa 100% E News, October/November 2001, Vol.1, no.7

Newsletter for the Information Technology Department

Iowa 100% E News, January 2002, Vol.2, no.1

Newsletter for the Information Technology Department

Iowa 100% E News, February 2002, Vol.2, no.2

Newsletter for the Information Technology Department

100 Years of Concrete Pavements in Iowa Final Report, March 2009

Portland cement concrete (PCC) pavements have given excellent service history for Iowa. The first concrete pavement was placed in Le Mars in 1904 and was in service until 1968. The Eddyville Cemetery Road placed in 1909 is still in service today. Many other pavements placed during the 1920s and 1930s are still in service today. The objective of this report is to document various changes in specifications, pavement design and equipment for PCC paving from the early 1900s to present. This includes changes that were made to the specification book and supplemental specifications. Where possible, information is given as a basis for the change in specifications.

Federal Highway Administration Finding of No Significant Impact Collins Road NE (Highway 100) Cedar Rapids, Linn County, Iowa, December 17, 2009

The proposed project consists of improving approximately 2.6 miles of Collins Road NE (Highway 100) in Cedar Rapids, Iowa. The project extends from the intersection of Center Point Road to approximately 750 feet east of its intersection with 1st Avenue.

Friday Facts, May 6, 2011, Vol. 100

Bureau of Nutrition and Health Promotion part of the Iowa Department of Public Health produces of weekly newsletter about the Iowa WIC Program for the State of Iowa citizen.