臺灣博碩士論文加值系統

鋼構造接頭中廣泛存在承受偏心載重的銲接接頭與螺栓接頭，諸如樑柱接合、梁與梁接合及托架等即為典型的承受偏心載重接頭。美國鋼結構協會(AISC)設計手冊使用彈性方法與瞬時旋轉中心法加以分析此類型接頭的設計強度。彈性方法較簡易，但通常得出過度保守的結果，而瞬時旋轉中心法雖可得到精確的結果，但其計算過程則顯得冗長繁瑣。目前的AISC設計手冊採用係數C值來評估接頭的設計強度，並提供了設計表格供使用者直接查閱各式螺栓群或銲接型態的接頭設計強度。但設計手冊只提供了六個特定角度的C值(0°, 15°, 30°, 45°, 60°, 75°)，對於其他的角度，依設計手冊的建議，避免使用直線內插法，必須採用直接分析的方法或在相鄰的特定角度之間採用較低的C值。對於其他的螺栓群配置或銲接型態，則必須採用直接分析的方法。遂此，本研究依據瞬時旋轉中心法的理論發展了一套直接分析流程，可普遍的應用在各種型態的螺栓群配置或銲接型態，並嘗試簡化繁瑣的直接分析，提出可評估任意角度偏心載重下接頭強度的非線性內插分析模式。應用此內插模式不僅計算快速簡單，而且相當精確。不僅避免冗長的計算，也無須在相鄰的特定角度之間採用較低的C值而犧牲分析的精確度。本研究克服了現行AISC設計手冊上的缺陷，在鋼結構承受偏心載重接頭的分析上，提供了快速且可靠的改善設計方法。

Fillet welded joints and bolted joints are widely used in steel construction. Eccentric loading of connections is often unavoidable. Eccentric connections occur in beam-to-column connections, web splice connections of beam, and bracket supports attached to column flanges. The American Institute of Steel Construction (AISC) permits the use of elastic and instantaneous center of rotation (IC) methods to analyze eccentric loaded connections. The elastic method normally yields relatively conservative designs and the IC method, which provides more realistic analyses, is rather complex and tedious. The current AISC manual provides tables for determining coefficient C, which are used to obtain the design strength of bolt group or weld patterns. However, the tables provide values for only six angles of inclination (θ  0°, 15°, 30°, 45°, 60°, and 75°). For other angles, either a direct analysis must be performed or the values for the next lower angle increment in the tables should be used for design is recommended in the manual except straight-line interpolation. This work develops an iterative algorithm to implement a direct analysis, and proposes a rational interpolation method between C values for loads at various angles not tabulated in manual tables without the tediousness of the IC method. The proposed method is easy to implement but reasonably accurate instead of using the C values for the next lower angle increment in the tables or direct analysis. This work eliminates the current limitations on AISC design manuals. It provides a quick but reliable improvement for the analysis and design of bolted or welded groups under eccentric loads in plane.

摘 要 i
Abstract ii
Contents iii
List of Figures v
List of Tables viii
Chapter 1 Introduction 1
1.1 General 1
1.2 Objectives and Scope 5
Chapter 2 Literature Review 7
2.1 Load-Deformation Relationship of a Bolt under Eccentric Loads 9
2.2 Available Studies on Bolted Groups under Eccentric Loads in Plane 10
2.3 Load-Deformation Relationship of Fillet Welds under Eccentric Load 14
2.4 Available Studies on Welded Groups under Eccentric Loads in Plane 18
2.5 Existing Iterative Algorithm for Locating the IC 20
2.6 Available Studies on Eccentrically Loaded Weld Joints Out-of-Plane 26
Chapter 3 Methods of Strength Evaluation 29
3.1 Instantaneous Center of Rotation Method 29
3.1.1 Determination for Instantaneous Center of Rotation 31
3.1.2 Optimum Algorithm of Step Size 41
3.2 Proposed New Model 46
3.3 Existing Strength Evaluation Models on Eccentrically Loaded Bolted Joints 51
3.4 Existing Strength Evaluation Models of Eccentrically Loaded Weld Joints 54
Chapter 4 Comparisons of Various Methods on Bolt Groups 58
4.1 Example of Bolt Groups 58
4.2 Discussions 62
Chapter 5 Comparisons of Various Methods on Fillet Welds 71
5.1 Example of C-shaped Welds 71
5.2 Example of Inverted L-shaped Welds 92
5.3 Example of Welds under Eccentric Loads Normal to the Plane of the Faying Surface 98
Chapter 6 Conclusions and Further Studies 105
Nomenclature 108
References 111

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