• Smart Structures and Systems
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• v.24 no.6
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• pp.723-732
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• 2019

Globally road transport networks are subjected to continuous levels of stress from increasing loading and environmental effects. As the most popular mean of transport in the UK the condition of this civil infrastructure is a key indicator of economic growth and productivity. Structural Health Monitoring (SHM) systems can provide a valuable insight to the true condition of our aging infrastructure. In particular, monitoring of the displacement of a bridge structure under live loading can provide an accurate descriptor of bridge condition. In the past B-WIM systems have been used to collect traffic data and hence provide an indicator of bridge condition, however the use of such systems can be restricted by bridge type, assess issues and cost limitations. This research provides a non-contact low cost AI based solution for vehicle classification and associated bridge displacement using computer vision methods. Convolutional neural networks (CNNs) have been adapted to develop the QUBYOLO vehicle classification method from recorded traffic images. This vehicle classification was then accurately related to the corresponding bridge response obtained under live loading using non-contact methods. The successful identification of multiple vehicle types during field testing has shown that QUBYOLO is suitable for the fine-grained vehicle classification required to identify applied load to a bridge structure. The process of displacement analysis and vehicle classification for the purposes of load identification which was used in this research adds to the body of knowledge on the monitoring of existing bridge structures, particularly long span bridges, and establishes the significant potential of computer vision and Deep Learning to provide dependable results on the real response of our infrastructure to existing and potential increased loading.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.5A
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• pp.447-456
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• 2009

The design comparison and flexural reliability analysis of continuous span composite plate girder bridges are performed. The girders are designed by the methods of allowable stress design (ASD) and load and resistance factor design (LRFD). For the LRFD design, the design specification under development mainly by KBRC, based on AASHTO-LRFD specification in case of steel structures, is applied with the newly proposed design live load which has been developed by analyzing domestic traffic statistics from highways and local roads. For the ASD based design, the current KHBDC code with DB-24 and DL-24 live loads is used. The longest span length for the 3-span continuous bridges with span arrangement ratio of 4:5:4 is assumed to be from 30 m to 80 m. The amount of steel, performance ratios, and governing design factors for the sections designed by the ASD and LRFD methods are compared. In the reliability analysis for the flexural failure of the sections designed by two methods, the statistical properties on flexural resistance based on the yield strength statistics for over 16,000 domestic structural steel samples are applied.

• Structural Engineering and Mechanics
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• v.27 no.4
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• pp.477-499
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• 2007

The main purpose of this paper is to investigate the ultimate behavior of steel cable-stayed bridges with design variables and compare the validity and applicability of computational methods for evaluating ultimate load capacity of cable-stayed bridges. The methods considered in this paper are elastic buckling analysis, inelastic buckling analysis and nonlinear elasto-plastic analysis. Elastic buckling analysis uses a numerical eigenvalue calculation without considering geometric nonlinearities of cable-stayed bridges and the inelastic material behavior of main components. Inelastic buckling analysis uses an iterative eigenvalue calculation to consider inelastic material behavior, but cannot consider geometric nonlinearities of cable-stayed bridges. The tangent modulus concept with the column strength curve prescribed in AASHTO LRFD is used to consider inelastic buckling behavior. Detailed procedures of inelastic buckling analysis are presented and corresponding computer codes were developed. In contrast, nonlinear elasto-plastic analysis uses an incremental-iterative method and can consider both geometric nonlinearities and inelastic material behavior of a cable-stayed bridge. Proprietary software ABAQUS are used and user-subroutines are newly written to update equivalent modulus of cables to consider geometric nonlinearity due to cable sags at each increment step. Ultimate load capacities with the three analyses are evaluated for numerical models of cable-stayed bridges that have center spans of 600 m, 900 m and 1200 m with different girder depths and live load cases. The results show that inelastic buckling analysis is an effective approximation method, as a simple and fast alternative, to obtain ultimate load capacity of long span cable-stayed bridges, whereas elastic buckling analysis greatly overestimates the overall stability of cable-stayed bridges.

• Tunnel and Underground Space
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• v.26 no.3
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• pp.192-200
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• 2016

We analyzed the behavior of the lining segments considering the middle slab and lateral pressure coefficients when planning the construction of a duplex tunnel for the underground network. Reviewed segment lining analysis for research, the analytical model was determined for duplex tunnel. Also reviewed the vertical load, and a load of middle slab is considered the static load and the live load by vehicles. Section force by middle slabs a load applied was mainly generated in the lower tunnel had the greatest effect on the bending moment. In addition, the bending moment acting direction changes appeared with a large variable, and the section force according to the load applied to the middle slab is relatively constant and the effect on the segment lining from the smallest section force of the lateral pressure coefficient of 1.00 was found to occur appears most significantly. As a result of this research to identify the behavior of the slab and the segment lining by the effect of the lateral pressure coefficient (K) of the duplex tunnel will be able to present a method of the duplex tunnel structure is reasonable and economical design.

• Steel and Composite Structures
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• v.42 no.6
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• pp.805-826
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• 2022

The free and live load-forced vibration behaviour of porous functionally graded (PFG) higher order nanobeams in the thermal and magnetic fields is investigated comprehensively through this work in the framework of nonlocal strain gradient theory (NLSGT). The porosity effects on the dynamic behaviour of FG nanobeams is investigated using four different porosity distribution models. These models are exploited; uniform, symmetrical, condensed upward, and condensed downward distributions. The material characteristics gradation in the thickness direction is estimated using the power-law. The magnetic field effect is incorporated using Maxwell's equations. The third order shear deformation beam theory is adopted to incorporate the shear deformation effect. The Hamilton principle is adopted to derive the coupled thermomagnetic dynamic equations of motion of the whole system and the associated boundary conditions. Navier method is used to derive the analytical solution of the governing equations. The developed methodology is verified and compared with the available results in the literature and good agreement is observed. Parametric studies are conducted to show effects of porosity parameter; porosity distribution, temperature rise, magnetic field intensity, material gradation index, non-classical parameters, and the applied moving load velocity on the vibration behavior of nanobeams. It has been showed that all the analyzed conditions have significant effects on the dynamic behavior of the nanobeams. Additionally, it has been observed that the negative effects of moving load, porosity and thermal load on the nanobeam dynamics can be reduced by the effect of the force induced from the directed magnetic field or can be kept within certain desired design limits by controlling the intensity of the magnetic field.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.3A
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• pp.199-207
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• 2009

In this paper, new vehicular load model is developed for reliability-based bridge design code. Rational load model and statistical properties of loads are important for developing reliability-based design code. In the previous paper, truck weight data collected at eight locations using WIM or BWIM system are analyzed to calculate the maximum truck weights for specified bridge lifetime. Probability distributions of upper 20% total truck weight are assumed as Extreme Type I (Gumbel Distribution) and 100 years maximum weights are estimated by linear regression. In this study, effects of multiple presence of trucks are analyzed. Probability of multiple presence of trucks are estimated and corresponding multiple truck weights are calculated using the same probability distribution function as in the previous paper. New vehicular live load model are proposed for span length from 10 m to 200 m. New model is compared with current Korean model and various load models of other countries.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.2A
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• pp.137-148
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• 2010

This study proposes the optimal ratio of vertical load-carrying capacity (${\beta}$) by investigating structural performances and economic efficiency in the extradosed bridges. Without design standards for the extradosed bridge, Japanese design standards have been used domestically. For the design live load, DL24 is found to be more adequate than DB24. Using the DL24 load, parameter studies are carried out. The parameters are 'main tower height', 'main girder stiffness', and 'cable arrangement'. As a result, it is found that one side cable-stayed extradosed bridges are more economical than double side cable-stayed extradosed bridges. This study also shows that when the ratio of vertical load-carrying capacity(${\beta}$) is 30~50% in the extradosed bridge with the ratio of tower height to main span length 1/6, the extradosed bridge is most economical because of the cable stress less than the allowable stress.

• Structural Engineering and Mechanics
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• v.50 no.4
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• pp.419-439
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• 2014

In this study, the structural performance of a seven span masonry arch bridge was evaluated. Investigations were performed on Aspendos (Belkis) Masonry Arch Bridge which was located on road of Aspendos Acropolis City in Antalya, Turkey. The old bridge was constructed in the early of fourth century AD, but it was exposed to the earthquakes in this region and the overloading by the river water. The old bridge was severely damaged and collapsed by probably an earthquake many years ago and a new bridge was then reconstructed on the remains of this old bridge by Seljuk in the 13th century. The bridge has also been affected from overflowing especially in the spring of each year, so some protective measures should be taken for this monumental bridge. Therefore, the structural performance under these loading has to be known. For this purpose, an initial finite element model was developed for the bridge and it was calibrated according to ambient vibration test results. After that, it was analyzed for different load cases such as dead, live, earthquake and overflow. Three load combinations were taken into account by deriving from these load cases. The displacements and the stresses for these combination cases were attained and compared with each other. The structural performance of Aspendos Masonry Arch Bridge was determined by considering the demand-capacity ratio for the tensile stress of the mortar used in Aspendos Masonry Arch Bridge. After these investigations, some concluding remarks and offers were presented at the end of this study.

• Earthquakes and Structures
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• v.5 no.5
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• pp.589-605
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• 2013

The effect of dead loads on dynamic responses of a uniform elastic beam subjected to moving loads is examined by means of a governing equation which takes into account initial bending stresses due to dead loads. First, the governing equation of beams which includes the effect of dead loads is briefly presented from the author's paper (1990, 1991, 2010). The effect of dead loads is considered by a strain energy produced by conservative initial stresses caused by the dead loads. Second, the effect of dead loads on dynamical responses produced by moving loads in simply supported beams is confirmed by the results of numerical computations using the Galerkin method and Wilson-${\theta}$ method. It is shown that the dynamical responses by moving loads are decreased remarkably on a heavyweight beam when the effect of dead loads is included. Third, an approximate solution of dynamic deflections including the effect of dead loads for a uniform beam subjected to moving loads is presented in a closed-form for the case without the additional mass due to moving loads. The proposed solution shows a good agreement with results of numerical computations with the Galerkin method and Wilson-${\theta}$ method. Finally it is clarified that the effect of dead loads on elastic uniform beams subjected to moving loads acts on the restraint of the transverse vibration for the both cases without and with the additional mass due to moving loads.

• Journal of the Korean Geotechnical Society
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• v.30 no.8
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• pp.5-11
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• 2014

The objective of this paper is to develop a rational reliability analysis procedure for the LRFD design provisions of bridge substructures. A bridge abutments is considered in this study. The reliability analysis is applied to determine the relationship between the major design parameters for bridge abutment and reliability index. The considered load components include dead load, vertical and horizontal earth pressure, earth surcharge, and vehicle live load. Several limit states are considered: foundation bearing capacity, sliding, and overturning. The analysis results show that the most important parameter in the reliability analysis is the effective stress friction angle of the soil. The reliability indices are calculated using Monte Carlo simulations for a selected bridge abutment. The results of the sensitivity analysis indicate that reliability index is most sensitive with regard to resistance factor and horizontal earth pressure factor.