- 摘 要
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（寧夏大學(xué)土木工程學(xué)院，銀川 750021）
［摘要］對管桁結(jié)構(gòu)直接焊接相貫節(jié)點中存在的焊縫，制作標(biāo)準(zhǔn)試件進行低周疲勞試驗，得到σ-ε滯回曲線、循環(huán)應(yīng)力幅值退化曲線，分析了焊材試件的破壞模式及在三種等幅循環(huán)荷載作用下滯回曲線的特點。利用ABAQUS軟件模擬試驗過程，與試驗滯回曲線做對比，并用Ramberg-Osgood模型擬合了循環(huán)應(yīng)力-應(yīng)變曲線。結(jié)果表明，焊材損傷累積破壞過程分為三個階段，裂紋萌生和破壞階段應(yīng)力幅退化較快，裂紋穩(wěn)定發(fā)展階段變化較慢；在循環(huán)荷載作用下，隨著循環(huán)周數(shù)的增加，焊材循環(huán)應(yīng)力幅值、卸載剛度和耗能能力均逐漸減小，呈現(xiàn)出循環(huán)軟化特性； ABAQUS模擬的滯回曲線與試驗曲線吻合較好，表明由循環(huán)加載試驗標(biāo)定的強化參數(shù)能用于有限元分析；Ramberg-Osgood模型能夠較好模擬循環(huán)應(yīng)力-應(yīng)變曲線。
［關(guān)鍵詞］管桁結(jié)構(gòu)；直接焊接節(jié)點；本構(gòu)關(guān)系；損傷累積；循環(huán)荷載
中圖分類號：TU393-3文獻標(biāo)識碼：A文章編號：1002-848X(2020)24-0035-07
Experimental study on constitutive relation of directly-welded joints of tubular truss structures under cyclic loading
LI Shuntao, YANG Wenwei, SUO Yaqi
(School of Civil Engineering, Ningxia University, Yinchuan 750021， China)
Abstract:To study the welds existing in directly-welded joints in the intersecting nodes of the tubular truss structure, standard specimens were made for low-cycle fatigue tests. The σ-ε hysteresis curve and the cyclic stress amplitude degradation curve were obtained, and the failure mode of the welding material specimen and the characteristics of the hysteresis curve under the action of three constant amplitude cyclic loads were analyzed. ABAQUS software was used to simulate the experimental process to compare with the experimental hysteresis curve, and Ramberg-Osgood model was used to fit the cyclic stress-strain curve. The results show that the cumulative damage of welding consumables is divided into three stages. The stress amplitude degenerates faster in the crack initiation and failure stages, and the crack stable development stage changes slowly; under the action of cyclic loading, as the number of cycles increases, the cyclic stress amplitude of the welding materials, unloading stiffness and energy dissipation capacity are gradually reduced, showing cyclic softening characteristics; the hysteresis curve simulated by ABAQUS is in good agreement with the test curve, and the strengthening parameters calibrated by the cyclic loading test can be used for finite element analysis; Ramberg-Osgood model can simulate the cyclic stress-strain curve well.
Keywords:tubular truss structure; directly-welded joint; constitutive relationship; damage accumulation; action of cyclic loading
*國家自然科學(xué)基金項目（51468054）。
作者簡介：李順濤，碩士，Email:lishuntaoqqq@live.com。
