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(貴州大學(xué)土木工程學(xué)院, 貴陽 550025)

摘要: 為了驗(yàn)證應(yīng)力加權(quán)損傷模型( SWDM)對相貫節(jié)點(diǎn)在單調(diào)荷載作用下延性斷裂預(yù)測的適用性,對正交設(shè)計(jì)的 23 個(gè) X 形圓鋼管相貫節(jié)點(diǎn)進(jìn)行有限元分析。 應(yīng)用空穴擴(kuò)張模型( VGM) 和 SWDM,得到了荷載和斷裂點(diǎn)損傷度曲線,通過洛德角參數(shù)的變化,分析了斷裂點(diǎn)的應(yīng)力狀態(tài),對比了 VGM 和 SWDM 預(yù)測結(jié)果;運(yùn)用 ABAQUS 子程序模擬了焊縫破壞 過 程,分 析 了 節(jié) 點(diǎn) 幾 何 參 數(shù) 對 焊 縫 承 載 力 的 影 響。 結(jié) 果 表 明: SWDM 預(yù) 測 的 斷 裂 荷 載 要 低 于VGM,斷裂點(diǎn)的應(yīng)力狀態(tài)是由軸對稱拉伸或壓縮狀態(tài)向平面應(yīng)變狀態(tài)的趨勢變化,通過引入洛德角參數(shù),SWDM 能準(zhǔn)確地模擬節(jié)點(diǎn)在不同應(yīng)力狀態(tài)下的損傷累積,預(yù)測精度高于 VGM,適用性更好;焊縫的開裂始于鞍點(diǎn)處,并迅速向冠點(diǎn)發(fā)展,導(dǎo)致節(jié)點(diǎn)破壞;節(jié)點(diǎn)支主管壁厚一定時(shí),支主管外徑比和主管徑厚比越大,焊縫承載力越低;《 鋼結(jié)構(gòu)設(shè)計(jì)標(biāo)準(zhǔn)》 (GB 50017—2017)中焊縫承載力計(jì)算公式未考慮焊縫受力不均勻的影響,計(jì)算結(jié)果會(huì)出現(xiàn)偏不安全的情況。

關(guān)鍵詞: 相貫節(jié)點(diǎn); 應(yīng)力加權(quán)損傷模型; 空穴擴(kuò)張模型; 斷裂預(yù)測模型; 焊縫承載力

中圖分類號:TU392. 3 文獻(xiàn)標(biāo)志碼:A 文章編號:1002-848X(2022)13-0099-07

DOI:10. 19701 / j. jzjg. 20211180

Fracture prediction and bearing capacity analysis of weld of tubular circular hollowsection X-joints

HAN Han, ZHENG Tao, WANG Xudong, HUANG Zhenghua

( School of Civil Engineering, Guizhou University, Guiyang 550025, China)

Abstract:In order to verify the applicability of stress-weighted damage model( SWDM) to the prediction of ductile fracture of tubular joints under monotonic loading, the finite element analysis was carried out on 23 tubular circular hollow section X-joints with orthogonal design. Using void growth model( VGM) and SWDM, the load and fracture point damage curves were obtained, the stress state of the fracture point was analyzed through the change of Lode angle parameters. The prediction results of VGM and SWDM were compared. ABAQUS subroutine was used to simulate the weld failure process, the influence of joint geometry parameters on weld bearing capacity was analyzed. The results show that the fracture load predicted by SWDM is lower than that predicted by VGM. The stress state of fracture point is a trend change from axisymmetric tensile or compressive state to plane strain state. By introducing the Lode angle parameter, SWDM can accurately simulate the damage accumulation of joints under different stress states. The prediction accuracy is higher than that of VGM, and the applicability is better. The cracking of the weld starts at the saddle point and develops rapidly to the crown point, leading to the destruction of the joint. When the wall thickness of branch pipe and main pipe is constant, the larger the outer diameter ratio of branch pipe and main pipe and the diameter thickness ratio of main pipe, the lower the bearing capacity of weld. The calculation formula of weld bearing capacity in Standard for design of steel structures ( GB50017—2017) does not consider the influence of uneven stress of weld, and the calculation results will be unsafe.

Keywords:tubular joint; stress-weighted damage model; void growth model; fracture prediction model; weld bearing capacity