Limit Capacity of Welded Box Girder after Considering Bending Property
Abstract
OBJECTIVE：To research the limit capacity of welded box girder after considering bending property.
METHODS： Firstly,literatures about box girder, bending property and limit capacity of welded box girder were searched.Then,experimental actions of the welded box girder were established,by which the limit capacity was studied.
RESULTS：After comparing box girder and other similar structures, it was proved that bending property had a great influence on the limit capacity of welded box girder.
CONCLUSIONS：The limit capacity of welded box girder after considering bending property was actively affected by the length, web plate thickness and strength grade of the structural elements that the welded box girder was composed of.
Keywords：welded box girder; bending property; limit capacity
结论：考虑屈曲性能后焊接箱形梁的极限承载力主要受组成焊接箱形梁的结构元件的长度、腹板厚度和强度等级的积极影响。
关键词：焊接箱形梁；屈曲性能；极限承载力
Introduction
The welded box girder (WBG) is widely used in civil engineering bridges and it is an important structure in the industry due to its extremely high stiffness and strength. As the innovation of steel materials and the updating of welding technology, more and more WBG have been adopted in large bridge construction. Based on the current situation, the study of the limit capacity of WBG is of great significance to the safety evaluation, bridge design and bridge construction.
Bending property and limit capacity
The limit capacity of WBG is closely related to its bending property, which decides the comprehensive mechanical behavior of the box girder. According to the tests, the maximum stress of box girder can be divided into three parts, including the upper and lower flanges, web plate and the connection between these parts. In the process of research and tests, bending property has been proved to be the key factor that controls the strength of WBG. Through studying, scientists have concluded that the limit capacity could be improved by optimizing the bending property of box girders structural parts.
Establishment of experimental action
To research the limit capacity of WBG under different conditions, practical tests were taken. The necessary experiment was to build four types of box girder and conduct static load test. The length to width ratio of each kind of box girder was 5:1 and the parameters of web plate and connection of beam were controlled respectively. After the experiment, the data in various conditions were accumulated.
Analysis of Experimental Results
After the careful accumulation and analysis of the test data, the influence of web plate thickness, web plate strength, connection type and length-width ratio on the bending property and ultimate bearing capacity of WBG have been found out:
1) Web plate thickness: increasing the web plate thickness led to the improvement of the limit capacity, but too thick web plate may cause an excessive increase in the total weight of the box girder.
2) Web plate strength: increasing the strength of the web plate was beneficial to the bearing capacity, but too large strength would easily lead to the local deformation of the web plate.
3) Connection type: the connection type had a great influence on the overall strength and bearing capacity of the box girder. The reinforced connection type was capable of providing higher bearing capacity than the simple connection type.
4) Length-width ratio: the length-width ratio of the box girder was an important factor affecting the overall bearing capacity. In general, a smaller length-width ratio would be beneficial for the improvement of the limit capacity.
Conclusion
In conclusion, the limit capacity of welded box girder after considering bending property is actively affected by the length, web plate thickness and strength grade of the structural elements that the welded box girder is composed of. After comparison of similar girder structure, by virtue of the experiments, it is concluded that the overall strength of box girder is greatly affected by the bending property.
