Prestressing the precast concrete slabs with external cables

Precast R.C. slabs are gaining an acceptance as a structural element for bridges. One of the difficulties in the construction using the precast R.C. slabs is an introduction of longitudinal prestress. Prestressing with internal cables is not practical for the precast concrete slabs because there exist transverse joints between each precast slab. On the other hand, longitudinal prestressing with external cables can be performed in a few steps. The purpose of this study is to strengthen the precast R.C. slabs by introducing prestress with external cables. Three steel-concrete composite bridge specimens, which are prestressed with the external cables anchored on steel girders, are constructed in the laboratory. Both pre-tension and post-tension methods are used to prestress the specimens and the test results of static as well as well as fatigue loadings are reported. The results indicate that longitudinal prestress with external cables is an effective method to introduce prestress to the precast R.C. slabs.