[{"data":1,"prerenderedAt":62},["ShallowReactive",2],{"q-114180-arch_structure-22":3},{"question":4,"neighbors":27,"sameNumber":46,"prev":35,"next":38},{"id":5,"classKey":6,"session":7,"year":8,"subject":9,"number":10,"groupStem":11,"ownStem":12,"stem":12,"options":13,"answer":18,"answerKind":20,"answerS":11,"answerNote":11,"images":21,"explanation":23,"withheld":11,"deepChars":24,"freq":25,"indexable":26},"arch-114180-801-0102-022","architect","114180",114,"建築結構",22,null,"桁架結構如下圖，a~d 桿件中何者軸拉力最大？ 1.5 m 3m 3m 1.5 m 2m 3@3 m = 9 m",{"A":14,"B":15,"C":16,"D":17},"a 桿件","b 桿件","c 桿件","d 桿件",[19],"D","single",[22],"\u002Fimages\u002Farch-114180-801-0102-022.png","本題考點：華倫式桁架弦桿與斜桿內力的比較——弦桿以截面法取力矩求，斜桿以截面剪力求，最後比較拉力大小。\n【正解理由】依題圖，跨度 3@3 m = 9 m、高 2 m，下弦節點在 0、3、6、9 m，上弦節點在 1.5、4.5、7.5 m，各受 4 kN 向下，左端鉸支承、右端滾支承。載重對稱，兩支承反力各為 (4 + 4 + 4) \u002F 2 = 6 kN。斜桿水平投影 1.5 m、垂直投影 2 m，桿長 2.5 m。a 為左邊第一格下弦，對上方 1.5 m 節點取力矩：a × 2 = 6 × 1.5，a = 4.5 kN（拉）。d 為中間格下弦，對上方 4.5 m 節點取力矩：d × 2 = 6 × 4.5 − 4 × 3，d = 7.5 kN（拉）。b、c 兩斜桿所在截面的剪力都是 6 − 4 = 2 kN，斜桿內力 2 × 2.5 \u002F 2 = 2.5 kN，其中 b 為拉力、c 為壓力。拉力最大者為 d 桿件 7.5 kN。故選 D。\n【逐項排除】\n(A) 不符。a 桿件拉力 4.5 kN；它靠近支承，力矩中心（1.5 m 處上弦節點）的彎矩較小，拉力小於中間格的 d。\n(B) 不符。b 桿件為拉力，但只承擔截面剪力 2 kN，換算成斜桿內力為 2.5 kN，遠小於 d 的 7.5 kN。\n(C) 不符。c 桿件同樣承擔 2 kN 剪力、內力 2.5 kN，而且受的是壓力而非拉力，不符合「軸拉力」的比較對象。\n(D) 符合。d 位在跨度中央附近，對應的彎矩最大，拉力 7.5 kN 為四者最大。\n【演算步驟】\n1. 支承反力：R = (4 + 4 + 4) \u002F 2 = 6 kN。\n2. a 桿：對 1.5 m 處上弦節點取力矩，a × 2 m = 6 kN × 1.5 m → a = 6 × 1.5 \u002F 2 = 4.5 kN（拉）。\n3. d 桿：對 4.5 m 處上弦節點取力矩，d × 2 m = 6 kN × 4.5 m − 4 kN × 3 m → d = (6 × 4.5 − 4 × 3) \u002F 2 = 7.5 kN（拉）。\n4. 斜桿幾何：水平 1.5 m、垂直 2 m，桿長 2.5 m。\n5. b、c 桿：截面剪力 V = 6 kN − 4 kN = 2 kN，斜桿內力 = 2 kN × 2.5 \u002F 2 = 2.5 kN；b 為拉、c 為壓。\n6. 比較拉力：d 7.5 kN ＞ a 4.5 kN ＞ b 2.5 kN，c 為壓力。\n【記憶點】簡支桁架下弦受拉、越靠跨中越大；斜桿只扛剪力，跨中附近剪力小。",565,1,true,[28,31,34,37,40,43],{"number":29,"session":7,"stem":30},19,"圖示 B 點受力的桁架結構，下列構件內力與支承反力的大小與方向的敘述何者正確？ 6m…",{"number":32,"session":7,"stem":33},20,"圖示桁架 A、I 點為鉸支承，在 D 點受向下 4 kN 荷重，下列關於構件內力與方…",{"number":35,"session":7,"stem":36},21,"下圖桁架結構中 C、D 為鉸支承，BC 桿之受力狀況，下列何者正確（T 為張力，C …",{"number":38,"session":7,"stem":39},23,"在圖示之三鉸拱結構中，A 點之水平反力為何？ 6P L A L L L",{"number":41,"session":7,"stem":42},24,"下圖框架之 A 點彎矩為何？ D 1 1 1 1",{"number":44,"session":7,"stem":45},25,"如圖所示剛構架，各構件 EI 值皆相等，基礎支承點 D 垂直下陷將使構件產生彎矩。若…",[47,50,53,56,59],{"number":10,"session":48,"stem":49},"113190","下列那種牆設計對於建築物耐震時水平強度的提升效果最好？圖中以網點圖樣填滿的部分為牆體…",{"number":10,"session":51,"stem":52},"112190","對一個寬度為 b 深度為 h 的矩形斷面梁的斷面模數（S）及塑性斷面模數（Z），下列…",{"number":10,"session":54,"stem":55},"111180","有關建築物耐風設計規範的要求，下列敘述何者錯誤？",{"number":10,"session":57,"stem":58},"110180","以下關於材料力學中常用物理量之單位，何者錯誤？",{"number":10,"session":60,"stem":61},"109180","關於鋼筋混凝土預鑄工法之敘述，下列何者最不適當？",1791863195505]