Comparison of Dynamic Characteristics of Prestressed and Reinforced Concrete Beams

Abstract

To determine the dynamic characteristics of bridges built with prestressed and reinforced concrete beams, the dynamic properties of such beams should be known. Prestressing force is applied to the prestressed concrete (PSC) beam, unlike reinforced concrete (RC) beam. In this study, it is aimed to compare the dynamic properties of PSC and RC beams with the same material, section properties and effective span length. Dynamic properties such as the mode shapes and periods of the PSC and RC beam were determined by means of the formulation found in the literature and a computer program that uses the finite element method. For this study I-beam with 0.90m height and 15m effective span length was selected as an example. The selected beam was considered separately as PSC and RC. In the PSC beam, eight low-relaxation Grade270 prestressing strand with 15mm (0.6 in.) diameter were used, unlike reinforced concrete beams. Three dimensional finite element models (FEM) of PSC and RC beam were constituted using SAP2000 software. At the end of the study, mode shapes and periods of PSC and RC beams obtained from analytical prediction by formulation and numerical by FEM were compared with each other.