• Journal of Korean Society of Steel Construction
• /
• v.18 no.5
• /
• pp.535-542
• /
• 2006

In this study, the effects of cross beams on the lateral distribution of live loads in composite rolled H-beam girder bridges, were investigated through three-dimensional finite element analysis. The parameters considered in this study were the inertial moment ratio between the main girder and the cross beam, the presence of the cross beam, and the number of cross beams. The live load lateral distribution factors were investigated through finite element analysis and the customary grid method. The results show that there was no difference between the bridge models with and without a cross beam. The cross beam of the beam and frame types also showed almost the same live load lateral distribution factors. However, the finite element analysis showed that the concrete slab deck plays a major role in the lateral distribution of a live load, and consequently, the effect of the cross beam is not so insignificant that it can be neglected.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.13 no.4 s.56
• /
• pp.180-187
• /
• 2009

The objective of this research is to verify the code-specified girder distribution factors (GDF) for continuous steel girder bridges by field testing. Previous analytical study revealed that current GDF's specified in AASHTO Standard and AASHTO LRFD, developed for the simple span bridges are conservative even for the continuous bridges. In this study, field tests were performed for three continuous steel girder bridges to validate the GDF's specified in the AASHTO codes. The results show that the code values are conservative when compared with field tests, and in some cases, too conservative. Also, strains measured from the field test are, in most cases, smaller than those expected from the analytical results. However, when the GDF's from measured strains are compared with GDF's from analysis, it is found that the analysis results are not conservative, and in some instance, the analytical results underestimate the actual GDF's, which can lead to a groundless notion of safety. In one case, test results showed that the code GDF's specified in AASHTO LRFD is too permissive. As a result, it is found that GDF's specified in AASHTO LRFD should be used with careful reservation.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.9 no.3
• /
• pp.151-160
• /
• 2005

Current bridge design codes do not clearly specify the girder distribution factors for continuous bridges. The objective of the paper is to validate the use of code-specified girder distribution factors for the continuous steel girder bridges, and to provide a basis for recommended girder distribution factors (GDF) for interior girders, suitable for evaluation of existing continuous steel girder bridges. This paper presents the procedure and results of 3-dimensional finite element analysis that were performed on five of continuous steel girder bridges to verify girder distribution factors. The analysis results showed that the live load moment distribution at the negative moment region is very similar to those at the positive moment region in continuous steel girder bridges. It was also found that the GDF's based on the strain values are similar to those based on the deflection. GDF's based on the deflection show marginally better distribution. The analysis results confirmed that the code specified GDF's for continuous steel girder birdges are very conservative.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.28 no.2
• /
• pp.131-138
• /
• 2015

In this paper, the modified live-load and designed formula are studied according to the fact the highway bridge design specifications are recently revised. The two examples for composite steel plates and PSC girder bridges are studied. The envelope is analyzed with the finite element models and lateral load distribution method applying the existing highway bridge specification(2010), the newly revised highway bridge specification(2015) and AASHTO LRFD. In case of composite steel plates, length changes between spans are studied, and in case of PSC girder. changes of the number of cross-beams and spans, and span-lengths, are analyzed.

• Journal of Korean Society of Steel Construction
• /
• v.19 no.2
• /
• pp.211-221
• /
• 2007

A structural reliability analysis of fatigue truck model for fatigue failure of highway steel bridges was performed by applying the Miner's fatigue damage rule expressed as a function of various random variables affecting fatigue damage. Among the variables, the statistical parameters for equivalent moment, impact factor, and loadometer were obtained by analyzing recently measured domestic traffic data, whereas the parameters on fatigue strength, girder distribution factor, and headway factor of the measured data available in the literature were used. The effects of various fatigue truck models, fatigue life, ADTT, fatigue detail category, loadometer, and gross vehicle weight of fatigue truck on the reliability index of fatigue damage were analyzed. It is expected that the analytical results presented herein can be used as a basic background material in the calibration of both fatigue design truck and fatigue load factor of LRFD specification.