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Issue 2: May-Aug. 2021

Issue 2: May-Aug. 2021

Published online on September 2021

Seismic Fragility Analysis of Case Study Failure of Showa Bridge During 1964 Niigata Earthquake

Partha Bhowmik, Swagata DebRoy, Rajib Saha

Abstract:Seismic design of pile foundation has gained special attention in last few decades after experiencing significant failures due to liquefaction during moderate to severe earthquakes. Seismic soil-pile foundation-structure interaction (SSPSI) was considered as an important phenomenon to explain the pile failure mechanism. In this context, present study attempts to assess the vulnerability of case study of Showa bridge pile foundation embedded in liquefiable susceptible ground considering SSPSI using OPENSeesPL. Both soil and structural nonlinearity considered in this study. Fragility analysis is performed using Monte-Carlo simulation (MCS) and multiple strip analysis (MSA) technique to calculate the probability of failure. First, the developed numerical model offers a well agreement with the observed response of case study structure. Probabilistic results indicate that maximum bending moment and displacement in pile are found to be higher in case of inertial interaction which may be due to P- effect. Fragility result infers significant vulnerability of pile foundation during liquefaction attributing serviceability, collapse and curvature ductility limit states criteria. While, curvature ductility demand criteria gives higher vulnerability concern for pile foundation in liquefied deposit and may be considered as governing seismic design criteria.

International Journal of Bridge Engineering, Vol. 9, No. 2, 2021: pp. 1-19

Vibration Analysis of Finger Type of Clutch Used in Power Transmission in HPFM

Pramod Belkhode, Sarika Modak

Abstract:The Human Powered Flywheel Motor (HPFM) system uses human muscular power and stores the energy in the flywheel in the form of a rotational kinetic energy at an energy input rate convenient to man. After storing maximum possible energy in the flywheel, the same can be made available to the process unit upon engaging the clutch. The flywheel deceleration time after clutch engagement depends on the process resistance. Hence the processes which are of intermittent nature and non-sensitive to speed variation of the input shaft of the process unit can be energized implementing this concept of (HPFM) Human Powered Flywheel Motor as the energy. Spiral jaw clutch was used for engagement to transfer the flywheel energy to process unit. With the spiral jaw clutch operational difficulties of frequently break down of the jaw tip. The breakage of the jaw tip was due to severe impact, shock and wear. It is required to have controlled acceleration device between flywheel shaft and input shaft of the process unit. The present situation needs a positive clutch having the capability of withstanding impact, shock and wear. These clutches are decided to be best for energizing process units adopting HPFM as an energy source. Clutches have fingers for transmission of driving forces and energy necessary for process units. These fingers work like cantilevers which are subjected to varying forces which induces forced vibrations in the fingers. The paper detailed the vibration analysis of fingers in a finger type torsional flexible clutches necessary for HPFM energies process machines.

International Journal of Bridge Engineering, Vol. 9, No. 2, 2021: pp. 21-32

Natural Frequency of Functionally Graded Decks Plates with Porosity Based on Higher-Order Plates Theory

Merdaci Slimane, Osama Mohammed Elmardi Suleiman Khayal, Hadj Mostefa Adda

Abstract:In this paper, free vibrations of Functionally Graded decks Plates (FGP) with two distribution even and uneven of porosity are investigated. The plate is modeled using higher-order shears deformation plate theory. It has been observed that during the manufacture of (FGP), micro-voids and porosities can occur inside the material. In the resolution and the determination of the equations of motion Hamilton principle is used. Since the deck plate is simply supported the Navier procedure will be retained. Thus, in this work, the investigation of the free vibration analysis of (FGP) deck plate taking into account the perfect and influence of these imperfect is established. Natural frequencies are obtained for porous (FGP) with edges simply supported and verified with the results shown in the literature. A numerical study is conducted to examine the effects of various parameters such as material properties, thickness ratios, geometric ratio and the porosity coefficient on natural frequencies of the (FGP). It is found that the effects of exponent graded and the porosity coefficient on the natural frequencies are significant.

International Journal of Bridge Engineering, Vol. 9, No. 2, 2021: pp. 33-50

Terrorist Actions on Long Bridges

Tassos P. Avraam, George T. Michaltsos

Abstract:This paper investigates the influence of an explosive load, due to a terrorist action, on the behavior of a long bridge, and studies the explosion characteristics and their effect on the bridge. The theoretical formulation is based on a continuum approach which has been used in literature to analyze such long or suspension bridges. The analysis is carried out with the modal superposition method. The resulting differential equations are solved using the Duhamel’s integral.

International Journal of Bridge Engineering, Vol. 9, No. 2, 2021: pp. 51- 62

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