Comparison of Dynamic Characteristics of Prestressed and Reinforced Concrete Beams

Year 2019, Volume: 7 Issue: 1, 37 - 44, 31.01.2019

Barbaros Atmaca

https://doi.org/10.29130/dubited.421496

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

Öngerilmeli ve Betonarme Kirişlerin Dinamik Karakteristiklerinin Karşılaştırılması

Abstract

Öngerilmeli ve betonarme kirişler kullanılarak inşa edilen köprülerin dinamik karakteristiklerini belirlemek için
köprülerde kullanılan kirişlerin dinamik özelliklerinin bilinmesi gerekmektedir. Öngerilmeli kirişlere, betonarme
kirişlerden farklı olarak öngerilme kuvveti uygulanmaktadır. Bu çalışmada malzeme, kesit özellikleri ve efektif
açıklık değerleri aynı olan öngerilmeli ve betonarme kirişlerin dinamik karakteristiklerinin karşılaştırılması
amaçlanmıştır. Öngerilmeli ve betonarme kirişlerin dinamik karakteristiklerinden mod şekilleri ve periyodların
belirlenmesinde, literatürde bulunan bağıntılar ve sonlu elemanlar yöntemine dayalı bilgisayar programı
kullanılmıştır. Bu çalışma için 15m uzunluğa 0.90m yüksekliğe sahip I kiriş örnek olarak seçilmiştir. Seçilen kiriş,
öngerilmeli ve betonarme olarak ayrı ayrı dikkate alınmıştır. Öngerilmeli kirişte, betonarme kirişten farklı olarak
15mm (0.6in.) çaplı sekiz tane 270K sınıfı öngerme kablosu kullanılmıştır. Kirişlerin sonlu eleman modelleri SAP2000 programı kullanılarak oluşturulmuştur. Çalışmanın sonunda öngerilmeli ve betonarme kirişlerin analitik
ve sayısal olarak elde edilen dinamik karakteristikleri birbiriyle karşılaştırılmıştır.

Keywords

Öngerilmeli kiriş, Betonarme kiriş, Doğal frekans, Mod şekilleri, Öngerme kuvveti

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