论文部分内容阅读
近年来,钢管混凝土节点在桥梁工程中的应用越来越广泛。因此需要对这些节点在疲劳荷载作用下的可靠性进行研究,以避免可能突然发生的灾难。对由具有方形中空截面(SHS)的弦杆和支撑构成的中空截面T形节点进行了分析。具有中空截面的弦杆中填充了混凝土,因此形成了焊接组合管状T形节点。对此类节点进行的静力加载试验,校验了应变状态,以确定容易产生裂纹的热点区的应力集中系数。同时也对平面内弯曲循环荷载作用下的支撑的焊接组合节点进行了疲劳试验,以得到应力范围-循环次数(S-N)关系曲线的数据。在焊接的组合管状T形节点的热点区得到的应力集中系数最大值远远小于无任何填充的中空截面T形节点中的应力集中系数最大值。无论是弦杆还是支撑,其中的焊接组合管状T形节点中的疲劳破坏,都是在构件的焊趾处形成初始裂纹以及裂纹的发展过程中产生的。大量的试验也表明,破坏往往是先在弦杆的焊趾处产生第一道裂纹。研究同时发现,填充的焊接组合管状T形节点也比无填充的中空T形节点具有更好的抗疲劳强度。通过运用热点区应力方法进行的疲劳分析,提出了应用于填充混凝土弦杆的中空T形节点的设计方法。
In recent years, the application of CFST joints in bridge engineering is more and more widely. Therefore, it is necessary to study the reliability of these nodes under the action of fatigue load in order to avoid the possible sudden disaster. Hollow section T-joints consisting of chords and supports with square hollow sections (SHS) were analyzed. The chord with a hollow section is filled with concrete, thus forming a welded combination tubular T-junction. The static load tests on such nodes verify the strain state to determine the stress concentration factor of the hot spot where cracks easily occur. At the same time, fatigue tests were carried out on the welded joints of the supports subjected to bending cyclic loads in plane to obtain the data of the relationship between the stress range and the number of cycles (S-N). The maximum value of stress concentration factor obtained in the hot spot of the welded combined tubular T-joints is far less than the maximum value of the stress concentration factor in the T-joints with no filled hollow cross-section. Both the chord and the support, the fatigue failure in the welded T-joints at the welded joints is caused by the formation of initial cracks and the development of cracks at the weld toe of the component. A large number of tests also show that the destruction is often the first crack in the toe of the chord. The study also found that filled welded tubular T-joints also have better fatigue strength than unfilled hollow T-joints. By using the fatigue analysis of hot zone stress method, a design method of hollow T-joints applied to chilled concrete chords is proposed.