Instrumentation for Long Term Field Structure and Model Structure Investigations. Investigation of the Contraction of Prestressed Concrete Bridges.

摘要

The general nature of the deterioration of prestressed concrete bridges through contraction in Nebraska is discussed and clearly illustrated through the use of photographs taken from a previous field study involving approximately 100bridges. The test program to determine the actual nature and cause of the deterioration process involves continued study of the 100existing bridges,two new instrumented field structures in a natural environment,and a new full-scale model structure in a partially controlled environment. The new structures were heavily instrumented with mechanical and electrical types of strain measurement devices,thermometer and humidity wells,and other deformation references. Essentially all of the devices were pre-embedded using tape-in-place techniques to avoid damage to the steel forms for the girders. This technique also gave quick access to ready-to-read installation points after girder forms were stripped. Detailed steps for the manufacture and installation of such devices are outlined.