• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.6
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• pp.589-597
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• 2015

In this paper, the live load model for the design of high-speed railway bridge is analyzed by statistic and probabilistic methods and the safety level that is given by the load factors of the load combination is analyzed. This study is a part of the development of the limit state design method for the railway bridge, and the train data collected from the Gyeongbu high-speed railway for about one month are utilized. The four different statistical methods are applied to estimate the design load to match the bridge design life and the results are compared. In order to examine the safety level that the design load combination of the railway bridge gives, the reliability indexes are determined and the results are analyzed. The load effect from the current design live load for the high-speed rail bridge which is 0.75 times of the standard train load is came out greater than at least 30-22% that from the estimated load from the measured data. If it is judged based on the ultimate limit state, there is a possibility of additional reduction of the safety factors through the reliability analysis.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.4
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• pp.1261-1270
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• 2013

The current domestic design criteria of live load employs DL-24 load and DB-24 load. Particularly for long span bridges above 45meters, DL-24 load is forced to apply and design them, since the shearing force and the moment of DL-24 load appears more dominate than those of DB-24. But it appeared that this DL-24 load didn't meet the vehicles traveling load, which affected bridges in real use. Hence this paper defined ML-24 load similar to the load applied to real bridges and also defined a new live load model, RL-24 load, after adjusting the existing DL-24 load, which doesn't meet the moment and the shearing force of ML-24. As the result of applying and reviewing RL-24 load to simple bridges of span of 45~60m, the results satisfying both the moment and the shearing force applied to bridges in real use by traveling load were attained. Besides, the applicability of it was examined in comparison with live load models of home and abroad.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.993-1000
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• 2006

Practical stability design method of main members of cable-stayed bridges is proposed and discussed through a design example. For this purpose, initial tensions of stay cables and axial forces of main members are firstly determined using initial shaping analysis of bridges under dead loads. And then the effective buckling length using system elastic/inelastic buckling analysis and bending moments considering $P-{\delta}-{\Delta}$ effect by second-order elastic analysis are calculated for main girder and pylon members subjected to both axial forces and moments, respectively. Particularly, load combinations of dead and live loads, in which maximum load effects due to live loads are obtained, are taken into account and effects of live loads on effective buckling lengths are investigated.

• Journal of Korean Society of Steel Construction
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• v.20 no.1
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• pp.183-193
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• 2008

The reliability analysis of simply-supported and continuous composite plate girder and box girder bridges under flexure was performed to provide a basic data for the development of LRFD c ode. The bridges were designed based on LRFD specification with newly proposed design live load which was developed by analyzing traffic statistics from highways and local roads. A performance function for flexural failure was expressed as a function of the flexural resistance of composite section and the design moments due to permanent load and live load. For the flexural resistance, the statistical parameters obtained by analyzing over 16,000 domestic structural steel samples were used. Several different values of bias factors for the live load moment from 1.0 to 1.2 were used. Due to the lack of available domestic measured data on the moment by permanent loads, the same statistical properties used in the calibration of ASHTO-LRFD were ap plied. The reliability indices for the composite girder bridges with various span lengths, different live load factors, and bias fact or for the live load were obtained by applying the Rackwitz-Fiessler technique.

• International Journal of Highway Engineering
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• v.18 no.1
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• pp.1-11
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• 2016

PURPOSES : This study estimated the load effect of a single heavy truck to develop a live load model for the design and assessment of bridges located on an expressway with a limited truck entry weight. METHODS : The statistical estimation methods for the live load effect acting on a bridge by a heavy vehicle are reviewed, and applications using the actual measurement data for trucks traveling on an expressway are presented. The weight estimation of a single vehicle and its effect on a bridge are fundamental elements in the construction of a live load model. Two statistical estimation methods for the application of extrapolation in a probabilistic study and an additional estimation method that adopts the extreme value theory are reviewed. RESULTS : The proposed methods are applied to the traffic data measured on an expressway. All of the estimation methods yield similar results using the data measured when the weight limit has been relatively well observed because of the rigid enforcement of the weight regulation. On the other hand, when the estimations are made using overweight traffic data, the resulting values differ with the estimation method. CONCLUSIONS : The estimation methods based on the extreme distribution theory and the modified procedure presented in this paper can yield reasonable values for the maximum weight of a single truck, which can be applied in both the design and evaluation of a bridge on an expressway.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2008.11a
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• pp.3-6
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• 2008

Heat release characteristics of live fire load are an important parameter for performance oriented fire safety design of a building. While investigations have been carried out on the fire load and its burning behavior in office, residential and commercial buildings and so on, little effort has been paid for the rational treatment of fire load in bookstore. In this report, burning behavior of typical combustible objects in bookstore are studied by measuring heat release rates of bookshelf with book.

• Structural Engineering and Mechanics
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• v.30 no.5
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• pp.559-576
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• 2008

Having established the initial geometry and cable force of a typical three span suspension bridge under permanent load, the additional maximum response of the cable and the stiffening girder due to live load are determined, by means of an analytic procedure, considering the girder first hinged at its ends and then continuous through the main towers. The problem of interaction between the cable and the stiffening girder is examined taking under due consideration the second order effects, whereby, through the analogy to a fictitious tensioned beam under transverse load, a closed -form solution is achieved by means of a simple quadratic equation. It is found that the behavior of the whole system is governed by five simple dimensionless parameters which enable a quick determination of all the relevant design magnitudes of the bridge. Moreover, by introducing these parameters, a set of diagrams is presented, which enable the estimation of the influence of the geometric and loading data on the response and permit its immediate evaluation for preliminary design purposes.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.977-984
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• 2006

Generally main girders and steel piers of temporary bridges form the steel rahmen structure. In this study, the rational stability design procedure for main members of temporary bridges is presented using 3D system buckling analysis and second-order elastic analysis. 2 types of temporary bridges, which are possible to be designed and fabricated in reality, are chosen and the buckling design for them is performed considering load combinations of dead and live loads, thermal load, and wind load. Effective buckling length of steel piers, effects of live loads on effective length of main members, transition of ~id buckling modes, and effects of second-order analysis are investigated through case study of 2 temporary bridges.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.21 no.4
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• pp.325-334
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• 2008

The standard prestressed concrete I-girder bridge (PSC I-girder bridge) is one of the most prevalent types for small and medium bridges in Korea. When determining the member forces in a section to assess the safety of girder in this type of bridge, the general practice is to use the simplified practical equations or the live load distribution factors proposed in design standards rather than the precise analysis through the finite element method or so. Meanwhile, the live load distribution factors currently used in Korean design practice are just a reflection of overseas research results or design standards without alterations. Therefore, it is necessary to develop an equation of the live load distribution factors fit for the design conditions of Korea, considering the standardized section of standard PSC I-girder bridges and the design strength of concrete. In this study, to develop an equation of the live load distribution factors, a parametric analysis and sensitivity analysis were carried out on the parameters such as width of bridge, span length, girder spacing, width of traffic lane, etc. As a result, the major variables to determine the size of distribution factors were girder spacing, overhang length and span length in case of external girders. For internal adjacent girders, the determinant factors were girder spacing, overhang length, span length and width of bridge. For internal girders, the factors were girder spacing, width of bridge and span length. Then, an equation of live load distribution factors was developed through the multiple linear regression analysis on the results of parametric analysis. When the actual practice engineers design a bridge with the equation of live load distribution factors developed here, they will determine the design of member forces ensuring the appropriate safety rate more easily. Moreover, in the preliminary design, this model is expected to save much time for the repetitive design to improve the structural efficiency of PSC I-girder bridges.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1A
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• pp.143-153
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• 2006

In design of bridges, estimation of actions and loadings is very important for the safety and maintenance of bridges. In general, effect of traffic loading on the bridge can be modeled as live load (including impact load) and fatigue load. For estimation of traffic loading, it is important to get reliable and comprehensive truck statistical data such as the traffic and weight information. To get statistical data, Bridge Weigh-In-Motion (BWIM), which measures the truck weights without stopping the traffic, is need to be developed. In this study, BWIM system with various functions is developed first. Then this system is used to get comprehensive truck data. Traffic loadings including fatigue and live loading are formulated from the truck data acquired from the bridges. Objectives of this study are to develop the BWIM system, to apply the system in test bridge in Highway, and to formulate the live and fatigue loading for bridge design.