• Structural Engineering and Mechanics
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• v.64 no.2
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• pp.213-223
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• 2017

Bridges are lifeline and integral components of transportation system that are susceptible to seismic actions, their vulnerability assessment is essential for seismic risk assessment and mitigation. The vulnerability assessment of bridges common in Pakistan is very important as it is seismically very active region and the available code for the seismic design of bridges is obsolete. This research presents seismic vulnerability assessment of three real case simply supported multi-span reinforced concrete bridges commonly found in northern Pakistan, having one, two and three bents with circular piers. The vulnerability assessment is carried through the non-linear dynamic time history analyses for the derivation of fragility curves. Finite element based numerical models of the bridges were developed in MIDAS CIVIL (2015) and analyzed through with non-linear dynamic and incremental dynamic analyses, using a suite of bridge-specific natural spectrum compatible ground motion records. Seismic responses of shear key, bearing pad, expansion joint and pier components of each bridges were recorded during analysis and retrieved for performance based analysis. Fragility curves were developed for the bearing pads, shear key, expansion joint and pier of the bridges that first reach ultimate limit state. Dynamic analysis and the derived fragility curves show that ultimate limit state of bearing pads, shear keys and expansion joints of the bridges exceed first, followed by the piers ultimate limit state for all the three bridges. Mean collapse capacities computed for all the components indicated that bearing pads, expansion joints, and shear keys exceed the ultimate limit state at lowest seismic intensities.

• Earthquakes and Structures
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• v.15 no.4
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• pp.411-417
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• 2018

To solve the seismic response problem of a vertical floating roof tank with base isolation, the floating roof is assumed to experience homogeneous rigid circular plate vibration, where the wave height of the vibration is linearly distributed along the radius, starting from the theory of fluid velocity potential; the potential function of the liquid movement and the corresponding theoretical expression of the base shear, overturning the moment, are then established. According to the equivalent principle of the shear and moment, a simplified mechanical model of a base isolation tank with a swinging effect is established, along with a motion equation of a vertical storage tank isolation system that considers the swinging effect based on the energy principle. At the same time, taking a 150,000 m 3 large-scale storage tank as an example, a numerical analysis of the dampening effect was conducted using a vibration mode decomposition response spectrum method, and a comparative analysis with a simplified mechanical model with no swinging effect was applied.

• Journal of the Korea institute for structural maintenance and inspection
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• v.5 no.1
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• pp.218-227
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• 2001

The purpose of this study was to estimate that the relations of weathering speed and shear strength of granite soil by tracing the weathering depth of granite soil from the very moment of its cutting. The results obtained this follows : This paper is about seismic performance of the EDF(Electricite De France) system, that is among various base isolator. A rational modeling of EDF system has been presented that used Nllink element. We get theoretical solutions of equation of motion of the system and compared with numerical solutions using a finite element program. The unification modeling is made by comparing with behavior using Newmark-${\beta}$ method when input earthquake acceleration data. Thus, a verified modeling will apply bridge structures or multi-degree of-freedom systems.

• Journal of the Korean Society of Hazard Mitigation
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• v.6 no.3 s.22
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• pp.29-35
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• 2006

Fiber element method in earthquake response analysis of bridges is used to represents a realistic flexural deformation according to nonlinear behavior of beam-column section. Nonlinear pseudo-static analysis of two column bent using fiber element is accomplished and failure mechanism of the plastic hinge region is studied. Load-displacement curve obtained by nonlinear pseudo-static analysis can be applicable to earthquake response analysis by capacity spectrum method. The nonlinear time history analysis of a full bridge model using fiber element experienced by the ground motion corresponding to the target response spectrum is accomplished. The result of time history analysis is similar to that of capacity spectrum method.

• Journal of international Conference on Electrical Machines and Systems
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• v.2 no.3
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• pp.275-282
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• 2013

Applications such as vibration isolation, gravity compensation, pick-and-place machines, etc., would benefit from (long-stroke) cylindrical/tubular permanent magnet (PM) actuators with integrated passive gravity compensation to minimize the power consumption. As an example, in component placing (pick-and-place) machines on printed circuit boards, passive devices allow the powerless counteraction of translator including nozzles or tooling bits. In these applications, an increasing demand is arising for high-speed actuation with high precision and bandwidth capability mainly due to the placement head being at the foundation of the motion chain, hence, a large mass of this device will result in high force/power requirements for the driving mechanism (i.e. an H-bridge with three linear permanent magnet motors placed in an H-configuration). This paper investigates a tubular actuator topology combined with passive gravity compensation. These two functionalities are separately introduced, where the combination is verified using comprehensive three dimensional (3D) finite element analyses.

• Journal of the Korean Society of Safety
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• v.16 no.2
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• pp.130-135
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• 2001

The additional stresses and displacements produced by the use of long rail, typical of the high-speed railway, are investigated for the Taiwan high-speed railway bridges. In addition, an important special feature of the Taiwan high Speed Railway Design Specifications specifies that service earthquake has to be considered during the rail-structure interaction analysis before evaluating the stresses and relative displacements of the bridge. As pound motion is taken into account under seismic event the seismic response of the structure is applied as displacement in the rail-structure interaction analysis. The stresses and relative displacements of the structure are checked according to the consideration of seismic loading.

• Journal of the Korean Society of Safety
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• v.28 no.1
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• pp.63-73
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• 2013

Dynamic strain history curve measured in the field is influenced by various factors such as vehicle type, speed, noise, temperature and running location etc.. Because such curve is used for vehicle weight estimation methodology suggested by Moses, exact strain history curve is the most important thing for exact estimation of vehicle weight. In this paper, effect of such factors mentioned above is investigated on the measured strain history curves, and results of weight estimation of vehicles are discussed quantitatively. From this study, it was known that temperature effect contained in the strain history curve measured for long time in-site gives the biggest effect on result of weight estimation and it can be removed by using the mode value. Furthermore, gross vehicle weight can be estimated within 5% error corresponding to A class of the European classification if effects of temperature and noise are removed and vehicle properties such as speed, axle arrangement and running location are considered properly.

• Clinics in Shoulder and Elbow
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• v.19 no.1
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• pp.51-58
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• 2016

The arthroscopic rotator cuff repair is now considered a mainstream technique with highly satisfactory clinical results. However, concerns remain regarding healing failures for large and massive tears and high revision rate. In recent decades, various repair strategies and construct configurations have been developed for rotator cuff repair with the understanding that many factors contribute to the structural integrity of the repaired construct. The focus of biomechanical test in arthroscopic repair has been on increasing fixation strength and restoration of the footprint contact characteristics to provide early rehabilitation and improve healing. These include repaired rotator cuff tendon-footprint motion, increased tendon-footprint contact area and pressure, and tissue quality of tendon and bone. Recent studies have shown that a transosseous tunnel technique provides improved contact area and pressure between rotator cuff tendon and insertion footprint, and the technique of using double rows of suture anchors to recreate the native footprint attachment has been recently described. The transosseous equivalent suture bridge technique has the highest contact pressure and fixation force. In this review, the biomechanical tests about repair techniques of rotator cuff tear will be reviewed and discussed.

• Journal of the Earthquake Engineering Society of Korea
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• v.23 no.5
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• pp.261-268
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• 2019

This paper proposes damage indices efficient on evaluating the seismic safety of cable-stayed bridges, especially dual-plane, cable-stayed bridges with H-type pylons. The research assumes that the location of accelerometers is already defined as given in the 2017 Ministry of the Interior and Safety (MOIS) guideline. In other words, the paper does not attempt to suggest optimal sensor location for the seismic safety evaluation of cable-stayed bridges. The proposed damage indices are based on those for building structures widely applied in the field already. Those include changes in natural frequencies and changes in relative lateral displacements. In addition, the study proposes other efficient damage indices as the rotation changes at the top of pylons and in the midspan of the girder system. Sensitivity analysis for various damage indices is performed through dynamic analysis using selected earthquake ground motions. The paper compares the effectiveness of the damage indices.

• Structural Monitoring and Maintenance
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• v.7 no.4
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• pp.367-392
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• 2020

The specific characteristics of near-field earthquake records can lead to different dynamic responses of bridges compared to far-field records. However, the effect of near-field strong ground motion has often been neglected in the seismic performance assessment of the bridges. Furthermore, damage to horizontally curved multi-frame RC box-girder bridges in the past earthquakes has intensified the potential of seismic vulnerability of these structures due to their distinctive dynamic behavior. Based on the nonlinear time history analyses in OpenSEES, this article, assesses the effects of near-field versus far-field earthquakes on the seismic performance of horizontally curved multi-frame RC box-girder bridges by accounting the vertical component of the earthquake records. Analytical seismic fragility curves have been derived thru considering uncertainties in the earthquake records, material and geometric properties of bridges. The findings indicate that near-field effects reasonably increase the seismic vulnerability in this bridge sub-class. The results pave the way for future regional risk assessments regarding the importance of either including or excluding near-field effects on the seismic performance of horizontally curved bridges.