• Smart Structures and Systems
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• v.20 no.5
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• pp.549-562
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• 2017

The US railroad network carries 40% of the nation's total freight. Railroad bridges are the most critical part of the network infrastructure and, therefore, must be properly maintained for the operational safety. Railroad managers inspect bridges by measuring displacements under train crossing events to assess their structural condition and prioritize bridge management and safety decisions accordingly. The displacement of a railroad bridge under train crossings is one parameter of interest to railroad bridge owners, as it quantifies a bridge's ability to perform safely and addresses its serviceability. Railroad bridges with poor track conditions will have amplified displacements under heavy loads due to impacts between the wheels and rail joints. Under these circumstances, vehicle-track-bridge interactions could cause excessive bridge displacements, and hence, unsafe train crossings. If displacements during train crossings could be measured objectively, owners could repair or replace less safe bridges first. However, data on bridge displacements is difficult to collect in the field as a fixed point of reference is required for measurement. Accelerations can be used to estimate dynamic displacements, but to date, the pseudo-static displacements cannot be measured using reference-free sensors. This study proposes a method to estimate total transverse displacements of a railroad bridge under live train loads using acceleration and tilt data at the top of the exterior pile bent of a standard timber trestle, where train derailment due to excessive lateral movement is the main concern. Researchers used real bridge transverse displacement data under train traffic from varying bridge serviceability levels. This study explores the design of a new bridge deck-pier experimental model that simulates the vibrations of railroad bridges under traffic using a shake table for the input of train crossing data collected from the field into a laboratory model of a standard timber railroad pile bent. Reference-free sensors measured both the inclination angle and accelerations of the pile cap. Various readings are used to estimate the total displacements of the bridge using data filtering. The estimated displacements are then compared to the true responses of the model measured with displacement sensors. An average peak error of 10% and a root mean square error average of 5% resulted, concluding that this method can cost-effectively measure the total displacement of railroad bridges without a fixed reference.

• Journal of the Earthquake Engineering Society of Korea
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• v.8 no.5 s.39
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• pp.91-99
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• 2004

In general, stadium structure with long span has low inherent natural frequency. In the stadium structure, structural behavior similar to resonance can be occurred easily by spectator rhythmical movements of which exciting period is small comparatively. It is required to investigate the safety and the serviceability of stadium structure. Therefore, there exists a necessity for accurate vibration analysis. Accurate analysis of stadium structure subjected to dynamic load is required for economical construction and safe design of stadium structure. Stadium structure should be modeled by refined mesh for accurate vibration analysis. As the mesh of stadium structure is refined, the number of divided elements increases in numerical analysis. The number of node is increased and numerous computer memories or computational time are required. So it is very difficult to analyze refine model of stadium structures by using the commercial programs. It is possible to efficient vibration analysis of stadium structure by finite element modeling method using equivalent beam element proposed in this paper, because the number of nodes is decreased remarkably.

• International Journal of Naval Architecture and Ocean Engineering
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• v.10 no.3
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• pp.376-384
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• 2018

Selection of suitable ice class for ships operation is an important but not simple task. The increased exploitation of the Polar waters, both seasonal periods and geographical areas, as well as the introduction of new international design standards such as Polar Code, reduces the relevancy of using existing experience as basis for the selection, and new methods and knowledge have to be developed. This paper will analyse what can be the limiting ice thickness for ships navigating in the Russian Arctic and designed according to the Finnish-Swedish ice class rules. The permanent deformations of ice-strengthened shell structures for various ice classes is determined using MT Uikku as the typical size of a vessel navigating in ice. The ice load in various conditions is determined using the ARCDEV data from the winter 1998 as the basic database. By comparing the measured load in various ice conditions with the serviceability limit state of the structures, the limiting ice thickness for various ice classes is determined. The database for maximum loads includes 3-weeks ice load measurements during April 1998 on the Kara Sea mainly by icebreaker assistance. Gumbel 1 distribution is fitted on the measured 20 min maximum values and the data is divided into various classes using ship speed, ice thickness and ice concentration as the main parameters. Results encouragingly show that present designs are safer than assumed in the Polar Code suggesting that assisted operation in Arctic conditions is feasible in rougher conditions than indicated in the Polar Code.

• Journal of the Korea institute for structural maintenance and inspection
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• v.7 no.2
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• pp.105-113
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• 2003

Because structural systems are becoming lighter and more flexible and have lower natural frequencies and dampings than before, coordinated rhythmic activities such as dancing, audience participation in arenas or concert halls, and aerobics result in undesirable levels of vibration. For rhythmic activities, it is resonant or near resonant behavior that result in significant dynamic amplification and hence human discomfort. The most rational design strategy is to provide enough of a gap between the natural frequency of a floor system and the dominant frequencies excited by planned human activities to assure reasonably that resonance will not occur. For the case study the vibration measurements were performed at the floor of a long-span multi-purpose hall during the rock concert of popular singer.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.35 no.2
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• pp.119-129
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• 2022

It is essential to control the lateral displacement and differential axial shortening of the vertical elements in high-rise buildings. The differential axial shortening can cause challenges in the serviceability and safety of non-structural and structural elements, respectively. Hence, in this study, the differential axial shortening of the vertical elements and effects of long term behaviors of concrete are analyzed in 120-story high-rise buildings via the construction sequence analysis. Consequently, the axial shortening of the vertical elements is classified into elastic, creep, and shrinkage shortening, and dominant factors to the maximum axial shortening are analyzed. In addition, the serviceability of the non -structural elements is checked with a differential axial shortening at 30 years after completion of construction, and member forces at design and construction stages in girders and outrigger walls are compared.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.2
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• pp.1-7
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• 2023

Durability was evaluated by performing a full-scale vertical load fatigue test and a wheel load performance test on the HRS, which reduces the replacement time of the existing expansion joint and improves serviceability to allow partial replacement by lane. As a result of the vertical load fatigue test, the maximum stress of the rail-type expansion joint is 170 MPa, which is about 47.8% of the yield strength of the HRS expansion joint rail 355 MPa. The vertical load fatigue test of the HRS expansion joint with improved serviceability set the size and load of the load plate according to the road bridge design standards, did not show any fracture behavior in the vertical load fatigue test and the wheel load performance test 2 million times, and its durability and safety were verified.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1A
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• pp.35-43
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• 2006

In this paper, procedures and research results involved in the development of glass reinforced composite bridge deck of hollow section were presented. Laminate design for the 3 cell deck section was performed. Structural characteristics such as serviceability, strength, failure and stability for DB24 load were analytically studied through the finite element analysis for the composite deck plate girder bridge. Composite deck tube was fabricated with pultrusion and extensive tests such as flexural test, girder-connection test, barrier-connection test, compression fatigue test and flexural fatigue test were carried out to evaluate structural behavior experimentally. Also, field load test was conducted for the demonstration plate girder bridge with composite deck and requirements for the strength and serviceability were reviewed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.1A
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• pp.35-43
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• 2010

The panels are used as a composite part of the completed deck. They replace the main bottom transverse deck reinforcement and also serve as a form surface for the cast-in-place concrete upper layer that contains the top of deck reinforcement. However, in order to apply the precast panels to bridges properly, it is necessary to fully understand the structural characteristics of joint in precast panels. Particularly, since the bridge deck is under repeated loads such as traffic loads, fatigue behavior and characteristics of joint should be investigated. In this paper, fatigue tests of composite deck with shear ties and loop joints were conducted. The fatigue tests were conducted with an application of repeated loading and wheel loading. Test results were analyzed to examine the current design code for fatigue of reinforcement bar and serviceability under repeated loading.

• Journal of the Society of Disaster Information
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• v.19 no.4
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• pp.851-858
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• 2023

Purpose: A study was conducted to ensure the structural safety of a raised girder bridge with improved cross-sectional efficiency compared to the conventional PSC girder. For this purpose, the cross-sectional specifications such as girder length, height, and width were determined, the arrangement of the tendons was designed, and the practical performance of the raised girder under static and dynamic loads was verified. Method: The static performance experiment examined the serviceability limit state by measuring behavioral responses such as deflection and cracking to primary and secondary static loads. In addition, the dynamic load loading experiment measured the acceleration and displacement behavior response over time to calculate the natural frequency and damping ratio to examine the usability limit state. Result: As a result of the static performance test, the deflection value based on the maximum applied load showed stable behavior, and the crack width measured at the maximum applied load level was very small, satisfying the serviceability limit state. In addition, a natural frequency exceeding the natural frequency calculated during the design of the dynamic loading experiment was found, and a damping ratio that satisfies the current regulations was found to be secured.

• Geomechanics and Engineering
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• v.11 no.2
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• pp.211-234
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• 2016

A total of 99 full-scale field load tests at 22 sites were compiled for this study to elucidate several issues related to the load-displacement behaviour of belled piers under axial uplift loading, including (1) interpretation criteria to define various elastic, inelastic, and "failure" states for each load test from the load-displacement curve; (2) generalized correlations among these states and determinations to the predicted ultimate uplift resistances; (3) uncertainty in the resistance model factor statistics required for reliability-based ultimate limit state (ULS) design; (4) uncertainty associated with the normalized load-displacement curves and the resulting model factor statistics required for reliability-based serviceability limit state (SLS) design; and (5) variations of the combined ULS and SLS model factor statistics for reliability-based limit state designs. The approaches discussed in this study are practical and grounded realistically on the load tests of belled piers with minimal assumptions. The results on the characterization and uncertainty of uplift load-displacement behaviour of belled piers could be served as to extend the early contributions for reliability-based ULS and SLS designs.