可靠度論文：基于可靠度要求的木材強度設計值確定

1、. 可靠度論文：基于可靠度要求的木材強度設計值確定【中文摘要】木材強度設計值的準確性及連接的可靠性直接影響木結構的安全,因而需要科學合理地確定進口規(guī)格材和層板膠合木的強度設計指標及正確地評估連接的可靠性。我國木結構設計規(guī)范GB50005-2003基于美國已有規(guī)格材的強度設計指標,按相同荷載作用下美國與我國木結構設計獲得相同截面尺寸的原則,即軟轉換方法,給出了進口北美規(guī)格材的強度設計指標。正在制定的膠合木結構技術規(guī)范實際上也按軟轉換方法給出了我國目測分等與機械彈性模量分等層板膠合木的強度設計指標。本文對目前采用的軟轉換方法的可行性進行了評估,發(fā)現(xiàn)其不足之處是認為美國木結構設計規(guī)范與我國規(guī)范具有相

2、同的可靠度要求。本文以進口加拿大規(guī)格材為例,分別采用JC法與MC法驗算了我國木結構設計規(guī)范規(guī)定的進口北美規(guī)格材強度設計值的可靠性;采用同樣的方法對目測分等與機械彈性模量分等層板膠合木的強度設計值進行了驗算。結果表明,我國木結構設計規(guī)范及膠合木結構技術規(guī)范給出的強度設計值偏高,不能滿足我國建筑結構可靠度設計統(tǒng)一標準GB50068-2001的要求。因此有必要重新確定這類木結構用材的強度設計值。本文給出了相應的確定方法,以供修編相關規(guī)范參考。我國對于木結構節(jié)點連接可靠性的研究還處于初期階段,本文給出了螺栓連接S、m及類屈服模式的功能函數(shù),然后對其可靠性進行了評估,為木結構節(jié)點連接可靠性的研究提供了參

3、考?！居⑽恼縏he accuracy of design values for wood and the reliability of connections affect the safety and reliability of timber structures. It is, therefore, necessary to specify the strength design values of imported dimension lumber and glued laminated timber and to to evaluate the reliability of co

4、nnections in a scientific and reasonable way. Based on the existing strength design values of American dimension lumber,the Code for Design of Timber Structures (GB50005-2003) specified the strength design values by using soft conversion method,which means to obtain the same cross-section size of wo

5、od member by GB50005-2003 and American National Design Specification under the same design loads. Technical code of glued laminated timber structures which is being developed uses the similar method as dimension lumber to determine the strength design values of glued laminated timber made of visuall

6、y stress-graded laminations and mechanically modulus-graded laminations. In this study, the feasibility of the soft conversion method is assessed. The results showed that the shortcoming of the current conversion method is that the U.S. standards and the Chinese code have the same reliability requir

7、ements for timber structures.In this paper, the imported Canadian dimension lumber is taken for examples, and the JC and MC method are used to evaluate the reliability of imported North American dimension lumber based on the strength design values given in the Code for Design of Timber Structures. T

8、he same methods are also used to evaluate the reliability of Glulam made of visually stress-graded laminations and mechanically modulus-graded laminations, based on the strength design values given in the Technical Code Glued Laminated Timber Structures.It is found out that the strength design value

9、s given in both codes are so large that do not satisfy the requirment of The Unified Code for Reliability Designof Building Structures GB50068-2001. It is useful to re-establish the strength design values of dimension lumber and Glulam based on the target reliability index specified in China, thus t

10、o provide reference for compiling and revising of the related codes.Study of the reliability of connections in timber structures in China is still in an early stage. In this study, the performance function of bolted connections with failure modes ofs、m andare presented, and the reliability of the co

11、nnections is evaluated . This can provide reference for future study.【關鍵詞】可靠度 規(guī)格材 層板膠合木 木結構連接【英文關鍵詞】reliability dimension lumber glued laminated timber (Glulam) wood connection【目錄】基于可靠度要求的木材強度設計值確定 摘要 4-5 Abstract 5 第1章 緒論 8-24 1.1 引言 8-9 1.2 木結構用材及連接 9-18 1.2.1 規(guī)格材 9-12 1.2.2 層板膠合木 12-15 1.2.3 木結構的

12、連接 15-18 1.3 課題背景 18-19 1.4 國內(nèi)外相關課題研究現(xiàn)狀 19-23 1.4.1 工程結構設計方法 19-20 1.4.2 可靠度的計算方法 20-21 1.4.3 木結構的可靠性 21-23 1.5 本文的主要工作 23-24 第2章 可靠度理論及在木結構中的應用 24-38 2.1 引言 24 2.2 可靠度的基本原理 24-26 2.2.1 結構的極限狀態(tài) 24 2.2.2 結構的功能函數(shù) 24-25 2.2.3 結構的可靠性與可靠指標 25-26 2.3 可靠度的計算方法 26-30 2.3.1 JC 法 26-29 2.3.2 Monte Carlo 模擬抽樣法

13、（MC 法） 29-30 2.4 可靠度理論在木結構中的應用 30-36 2.4.1 木結構的抗力與荷載分析 30-33 2.4.2 木結構的功能函數(shù) 33-36 2.5 MATLAB 語言 36-37 2.6 小結 37-38 第3章 進口北美規(guī)格材強度設計值的計算 38-61 3.1 引言 38 3.2 進口北美規(guī)格材強度設計值的可靠度評估 38-42 3.3 進口北美規(guī)格材強度設計值的調整建議 42-59 3.3.1 C、C、C、C 等級規(guī)格材 42-56 3.3.2 其它等級規(guī)格材 56-59 3.4 小結 59-61 第4章 層板膠合木強度設計值的計算 61-73 4.1 引言 61 4.2 膠合木結構技術規(guī)范確定強度設計值方法的探討 61-63 4.3 層板膠合木強度設計值的可靠度評估 63-66 4.4 層板膠合木強度設計值的調整確定 66-72 4.4.1 基于最小可靠指標 66-68 4.4.2 基于平