[{"data":1,"prerenderedAt":62},["ShallowReactive",2],{"q-106180-arch_structure-23":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-106180-801-0102-023","architect","106180",106,"建築結構",23,null,"如圖所示桁架，桿件 ED 的內力為何？",{"A":14,"B":15,"C":16,"D":17},"6tf 壓力 G","0 3m E","10tf 壓力 3m C 6tf","6tf 張力 3m F D B A 4m 4m 4m KPL",[19],"B","single",[22],"\u002Fimages\u002Farch-106180-801-0102-023.png","本題考點：桁架零力桿的判定與節點法。三桿交會、其中兩桿共線且節點無外力時，第三桿為零力桿；連鎖套用即可一路推到 ED 桿。\n【正解理由】依題圖，F、D、B、A 在下弦一直線上，G、E、C、A 在上弦一直線上，B–C、D–E 為豎桿，D–C、F–E 為斜桿，外力只有 A 點向下 6 tf。節點 B：只連 BA、BD、BC 三桿，BA 與 BD 共線、B 點無外力，所以 BC 為零力桿。節點 C：連 CA、CE（同在上弦、共線）、CB（零力）與 CD，C 點無外力，垂直於上弦方向的平衡只剩 CD 一桿，所以 CD 也是零力桿。節點 D：連 DF、DB（下弦、共線、水平）、DC（零力）與 DE，垂直方向的力只剩 DE，D 點無外力，故 DE 內力為 0，故選 B。\n【逐項排除】\n(A) 6tf 壓力：6 tf 是 A 點外力的大小，不是 ED 桿內力；D 點垂直平衡只剩 ED 一桿，內力必須為零，談不上壓力或張力。\n(B) 0：正解。由 B → C → D 連續判定零力桿，ED 為零。\n(C) 10tf 壓力：10 tf 是上弦 AC 桿的內力大小，由 A 點垂直平衡 F_AC × 3\u002F5 = 6 求得，而且 AC 是張力不是壓力；把別根桿件的內力與方向套到 ED，桿件與受力性質兩處都不符。\n(D) 6tf 張力：與 (A) 一樣把 6 tf 當成 ED 的內力，數值與正確值 0 不符。\n【演算步驟】\n① 節點 A：AC 斜率為豎 3 m、水平 4 m、斜長 5 m，ΣFy = 0 → F_AC × 3\u002F5 = 6 tf → F_AC = 6 × 5\u002F3 = 10 tf（張力）。\n② 節點 B：BA、BD 共線，ΣFy = 0 → F_BC = 0 tf。\n③ 節點 C：CA、CE 共線，F_CB = 0 → 垂直上弦方向只剩 CD → F_CD = 0 tf。\n④ 節點 D：DF、DB 水平共線，ΣFy = 0 → F_DE + F_DC × 3\u002F5 = 0 → F_DE = −0 × 3\u002F5 = 0 tf。\n【記憶點】三桿節點兩桿共線、無外力 → 第三桿為零；零力桿可以連鎖推下去。",422,1,true,[28,31,34,37,40,43],{"number":29,"session":7,"stem":30},20,"建築結構除了耐風的強度設計外，規範仍要求檢討風力作用下建築物的容許層間變位角，其中耐…",{"number":32,"session":7,"stem":33},21,"下圖結構原為不穩定，擬於各節點間增加兩根桿件進行改善，則下列選項何者仍為不穩定結構？",{"number":35,"session":7,"stem":36},22,"型鋼會因製造過程產生殘餘應力（residual stress），下列敘述何者錯誤？",{"number":38,"session":7,"stem":39},24,"下圖桿件之自由端 a 點受 2P 力作用，a 點垂直向下伸長量為 δ av = ，則…",{"number":41,"session":7,"stem":42},25,"有一矩形梁斷面，梁寬 30 cm，梁高 60 cm。已知材料之彈性係數為 20,00…",{"number":44,"session":7,"stem":45},26,"下圖簡支梁之跨度為 L。已知材料之彈性係數為 E，梁斷面之慣性矩為 I。今於跨度中央…",[47,50,53,56,59],{"number":10,"session":48,"stem":49},"114180","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":10,"session":51,"stem":52},"113190","土壤液化會造成完工後的建築物下陷或傾斜，下列針對土壤液化現象的敘述，何者錯誤？",{"number":10,"session":54,"stem":55},"112190","如下圖所示之四種桁架結構，各桿件之軸向剛度（AE）值皆相等。若溫度改變時，何者最有可…",{"number":10,"session":57,"stem":58},"111180","受均佈載重 w 之梁結構如下圖所示，A 為鉸支承（hinge），B 為滾動支承（ro…",{"number":10,"session":60,"stem":61},"110180","一纜索受到以下的均勻分布載重作用下，若不考慮纜索自重，其弧線會呈現何種線型？",1791863211997]