【摘要】：受彎構(gòu)件的抗彎性能參數(shù)主要包括抗彎強度和轉(zhuǎn)動能力。現(xiàn)行抗震設(shè)計方法實際上允許構(gòu)件在強震作用下產(chǎn)生非彈性變形,以滿足設(shè)計經(jīng)濟性的需求。事實上,延性是評估結(jié)構(gòu)非彈性的參數(shù)。影響構(gòu)件延性的因素主要包括截面尺寸、支撐條件、荷載類型、加工偏差(初始缺陷和殘余應(yīng)力)及材料性能。本研究旨在考察高強鋼工字型截面受彎構(gòu)件的延性和承載力。共進行了6個高強鋼工字型截面梁繞強軸彎曲的足尺試驗,其中3個構(gòu)件采用翼緣為高強鋼、腹板為普通鋼的混合截面,3個構(gòu)件采用純Q345鋼截面。同時建立了鋼梁的三維有限元模型,并用試驗結(jié)果進行驗證。驗證時考慮了材料非線性和加工初始缺陷的影響,并引入實測的應(yīng)力-應(yīng)變關(guān)系。結(jié)果表明,試驗和有限元分析得到的彎矩-轉(zhuǎn)角曲線和極限承載力均十分一致�；诖�,選取荷載工況、材料特性、截面類型、截面幾何尺寸和側(cè)向支撐情況等參數(shù),開展了全面的參數(shù)分析。為了確保鋼梁能夠合理承載,規(guī)范中通常要求采用緊實截面,并對梁的側(cè)向支撐條件進行了規(guī)定�，F(xiàn)有研究表明規(guī)范中的寬厚比限值對于高強鋼梁而言是不合理的。因此,本文嘗試研究翼緣、腹板寬厚比和側(cè)向支撐間距對于鋼梁(包括混合截面梁和純高強鋼截面梁)延性的影響。本文基于等效塑性彎矩指標提出了一個新的計算構(gòu)件在純彎作用下轉(zhuǎn)動能力的理論方法,并用數(shù)值方法對所提的理論方法進行了驗證,以確保該方法的準確性�，F(xiàn)行規(guī)范中截面分類考慮了截面對于局部失穩(wěn)的敏感性,對于受彎構(gòu)件設(shè)計而言至關(guān)重要。事實上,在眾多現(xiàn)行規(guī)范中,對由翼緣或腹板失穩(wěn)控制的截面,延性概念已經(jīng)應(yīng)用其中,但翼緣和腹板的限值是獨立的。這種假設(shè)是不合理的,因為翼緣和腹板相互具有約束作用,這種相互作用必須考慮。因此,構(gòu)件性能分級應(yīng)該取代上述的截面性能分級。在構(gòu)件層面上,現(xiàn)有研究提出了一種基于構(gòu)件轉(zhuǎn)動能力的受彎構(gòu)件分類方法,這種方法考慮了局部失穩(wěn)和相關(guān)失穩(wěn)模式的相互影響,并收錄到中國鋼結(jié)構(gòu)設(shè)計規(guī)范最新版之中。根據(jù)上述參數(shù)分析的結(jié)果,本文還提出了一種確定工型梁抗彎承載力的新方法,這種方法基于在設(shè)計過程中與截面分類獨立的長細比參數(shù),并考慮了局部與整體相互作用的不穩(wěn)定性。事實上,本方法旨在簡化現(xiàn)行的受彎構(gòu)件設(shè)計流程。最后,開展了本方法與EC3和AISC的對比研究,結(jié)果表明本方法與現(xiàn)行EC3的結(jié)果十分一致。
[Abstract]:The bending performance parameters of bending members mainly include bending strength and rotation ability. The current seismic design method actually allows the inelastic deformation of the member under strong earthquake to meet the demand of design economy. In fact, ductility is a parameter to evaluate the inelasticity of a structure. The main factors affecting the ductility of the members include section size, supporting conditions, load types, machining deviations (initial defects and residual stresses) and material properties. The purpose of this study is to investigate the ductility and bearing capacity of high-strength steel I-section flexural members. Six I-section beams of high strength steel were subjected to full-scale bending tests around the strong axis. Among them, three members were made of high strength steel with flange, the web was a mixed section of ordinary steel, and three members were made of pure Q345 steel section. At the same time, the three-dimensional finite element model of steel beam is established and verified by test results. The effects of material nonlinearity and initial defects are considered, and the measured stress-strain relationship is introduced. The results show that the bending moment-angle curve and ultimate bearing capacity obtained from the test and finite element analysis are in good agreement. Based on this, the parameters such as load condition, material characteristics, cross-section type, cross-section geometry and lateral bracing are selected, and a comprehensive parameter analysis is carried out. In order to ensure that the steel beam can carry load reasonably, the compacted section is usually required in the code, and the lateral bracing condition of the beam is stipulated. Current studies show that the width-thickness ratio limit in the code is unreasonable for high-strength steel beams. Therefore, the effects of flange, web width to thickness ratio and lateral bracing spacing on the ductility of steel beams (including mixed section beams and pure high strength steel section beams) are studied in this paper. Based on the equivalent plastic moment index, a new theoretical method for calculating the rotation capacity of members under pure bending is proposed in this paper. The proposed method is verified by numerical method to ensure the accuracy of the method. The section classification in current codes takes into account the sensitivity of section to local instability, which is very important for the design of flexural members. In fact, the concept of ductility has been applied to the section controlled by flange or web instability, but the limit of flange and web is independent. This assumption is unreasonable because the flange and web are bound by each other and this interaction must be taken into account. Therefore, the component performance classification should replace the section performance classification mentioned above. At the component level, a classification method of bending members based on the rotation ability of members is proposed. This method takes into account the interaction between local instability and related instability modes, and is included in the latest edition of the Code for Design of Steel structures in China. Based on the results of the above parameter analysis, a new method for determining the flexural bearing capacity of beams is proposed. This method is based on the slenderness ratio parameters, which are independent of the section classification in the design process. The instability of local and global interaction is considered. In fact, this method aims to simplify the current design process of bending members. Finally, a comparative study of this method with EC3 and AISC is carried out. The results show that the method is in good agreement with the current EC3 results.
【學(xué)位授予單位】：清華大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2014
【分類號】：TU391

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