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.
Keywords
Prestressed beam,Reinforced beam,Natural frequency,Mode shapes,Prestressing force
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