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International Research Journal of Engineering and Technology (IRJET)

e-ISSN: 2395-0056

Volume: 10 Issue: 07 | July 2023

p-ISSN: 2395-0072

www.irjet.net

A Study on Dynamic Amplification Factor for Highway Bridges Mr. Prajwal Ulape1, Dr. M.R. Shiyekar 2, 1PG Student, Structural Engineering Department, Government College of Engineering, Karad,

Maharashtra, India.

2Professor, Structural Engineering Department, Government College of Engineering, Karad,

Maharashtra, India. ---------------------------------------------------------------------***---------------------------------------------------------------------

Abstract - Moving vehicle mass induces significant

depend on factors mentioned above [3]. In past years, theories are proposed if the impact factors mentioned in various national specifications are adequate for present traffic flow and road conditions. According to reports, impact factors calculated using current codes may drastically underestimate bridge response in many circumstances.[4]. Dynamic effects caused due to live loads must be considered while bridge design. The dynamic amplification factor (DAF) can be defined as, a dimensionless number which describes how many times the deflections or stresses should be multiplied to the deflections or stresses due to static loads when structure is subjected to dynamic loading [5]. As referred in various national design specifications, the total dynamic effect of live load is calculated by multiplying DAF to static response of the structure [6]. In general, a dynamic amplification factor analysis of a highway bridge under moving loads is performed, which provides often accurate results depending on the parameters stated, and the value is compared to the standard values specified in national codes. In India IRC class A and class B loading are considered for designing bridges including impact factor as specified by Indian Road Congress in IRC-06. A specified in IRC-6[14]. impact factor for bridge structure subjected to moving vehicle of IRC class A and class B loading depends upon the bridge characteristics viz. if the bridge is Steel bridge or Reinforced Cement Concrete (RCC) bridge. Impact factor due to live loading is influenced by span length of the bridge. When bridge is subjected to moving vehicle loading dynamic response of the bridge changes with variation in vehicle velocity. At present vehicle velocity is completely ignored while designing bridge structure [7]. The research of all parameters is necessary to arrive at the correct quantitative value of DAF, and it is crucial to accurately analyse how a highway bridge behaves when heavily loaded both for the improvement of design methods and for the evaluation of existing bridges. This study mainly focuses dynamic response of five simply supported bridge structures subjected to moving vehicle load. IRC class A and class B loading are considered as design loads. Static and dynamic response of the bridge are computed for each span length and vehicle velocity. A simply supported 2-lane bridge structure is modelled [8] using bridge wizard provided in SAP2000 software. SAP2000 allows static and dynamic analysis of bridge structure subjected to vehicle-bridge interaction with ease and accuracy.

vibratory effect on the bridge structure. Such dynamic effects on bridge can cause higher stresses and deflections in bridge than the static deflections and stresses of equal magnitude. Hence, dynamic effects of bridges are needed to be taken into considerations. The term Dynamic amplification factor (DAF) is used to evaluate the dynamic effect of the bridge. The total dynamic effect of live load is obtained by multiplying. DAF to static response of the structure Accurate investigation of dynamic response of the bridge is complicated and cumbersome procedure, which involves various parameters. Therefore, there is an urgent need to develop an accurate method to evaluate DAF. In actual practice, there exists no rational method to evaluate DAF caused due to moving load over structure. An analytical investigation is carried out to find the effect of vehicle velocity and span length on DAF for bridge structure using SAP2000. The main focus of this study is to analyze the static and dynamic behavior of RCC longitudinal girder and Concrete decks bridge caused by the vehicular loading IRC Class A and Class B loading with different vehicle velocity. Considering different span lengths subjected to IRC class A and class B loading with variable velocity, Dynamic amplification factor (DAF) is evaluated. It is observed that DAF varies with change in vehicle velocity. Also, DAF values for both class A and class B loading are different. Key Words: DAF, impact factor, dynamic response, SAP2000, vehicle-bridge interaction, IRC loading, Finite element analysis.

1. INTRODUCTION The moving vehicle mass system causes vibration on the highway bridge, which has become a crucial problem that must be investigated. Moving vehicles on the bridge generate significantly more stresses and deformations than static deformations and stresses of equal magnitude at a single section [1]. The dynamic response of a bridge and its mechanism is complex problem involves vehicle bridge interaction and the influence of a large number of components such as bridge dynamic features, vehicle characteristics, road surface roughness, vehicle speed, traffic flow conditions, and so on [2]. Many bridge engineers tackle such induced vibration concerns by taking solely the impact factors stipulated in their national codes into account, even though vibration response may

Impact Factor value: 8.226

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