[{"data":1,"prerenderedAt":62},["ShallowReactive",2],{"q-105170-arch_structure-14":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-105170-801-0102-014","architect","105170",105,"建築結構",14,null,"二懸臂梁在同一平面上，於自由端以連桿連接成鉸點之系統，則此結構之穩定與靜不定性質為何？",{"A":14,"B":15,"C":16,"D":17},"靜定","一次靜不定","二次靜不定","三次靜不定",[19],"C","single",[22],"\u002Fimages\u002Farch-105170-801-0102-014.png","本題考點：由兩根懸臂梁以連桿相接所組成之系統的穩定性與靜不定度判別，重點是辨認「兩根交叉連桿」相當於一個鉸接點。\n【正解理由】依題圖所示，兩根懸臂梁各自一端為固定端，自由端之間以兩根交叉的連桿相連。每根連桿只能傳遞沿桿軸方向的力，兩根交叉連桿的軸線交於一點，合起來能傳遞任意方向的兩個力分量，卻不能傳遞彎矩，作用等同於一個鉸接點，題目也說明「連接成鉸點」。計算靜不定度：兩個固定端各 3 個反力，共 6 個；兩根連桿各 1 個未知軸力，共 2 個；未知數合計 8 個。兩根梁各自取自由體，每根 3 個平衡方程式，共 6 個。8 − 6 = 2，屬二次靜不定。另一個角度：若兩根梁直接剛接，就是兩端固定梁，三次靜不定；改成鉸接釋放 1 個彎矩束制，剩二次。兩根梁各自固定在牆上，不會形成機構，結構穩定。故選 C。\n【逐項排除】\n(A) 不正確。單一根懸臂梁本身已經是靜定，兩根懸臂梁再以連桿互相連接，就多出了連桿的束制，不可能仍是靜定。要靜定，兩根梁之間必須完全不相連。\n(B) 不正確。一次靜不定代表只多出 1 個多餘束制，相當於只用一根連桿連接兩根懸臂梁。本題是兩根交叉連桿，形成可傳遞兩個力分量的鉸接點，多出 2 個束制。\n(C) 正確。未知數 8 個（固定端反力 6 個加連桿軸力 2 個）減去方程式 6 個，得二次靜不定。\n(D) 不正確。三次靜不定是兩根梁在接點處剛接（可傳遞彎矩）時的情況。本題接點是鉸點，彎矩無法傳遞，少 1 個束制，所以是二次。\n【演算步驟】\n未知數：固定端反力 3 個 + 3 個 = 6 個；連桿軸力 2 個；合計 3 個 + 3 個 + 2 個 = 8 個。\n方程式：每根梁 3 個平衡方程式，兩根共 3 個 + 3 個 = 6 個。\n靜不定度 = 8 個 − 6 個 = 2 次。\n【記憶點】兩根不平行的連桿交於一點等於一個鉸；兩端固定梁中間開一個鉸，靜不定度由三降為二。",532,1,true,[28,31,34,37,40,43],{"number":29,"session":7,"stem":30},11,"對矩形斷面梁而言，寬度為 b，高度為 h，則其斷面模數（section modulu…",{"number":32,"session":7,"stem":33},12,"簡支梁兩端承受力矩作用後變形如下圖所示，若梁左右兩端轉角 θa、θb 皆為，則梁右端…",{"number":35,"session":7,"stem":36},13,"關於結構韌性（ductility）之敘述，下列何者正確？",{"number":38,"session":7,"stem":39},15,"有一柱，若其有效長度及挫屈載重分別為 KL 與 Pcr ，今將其有效長度增加一倍為 …",{"number":41,"session":7,"stem":42},16,"下圖剛架受水平地震力時，最少出現幾個塑鉸時就會崩塌？",{"number":44,"session":7,"stem":45},17,"臺灣的學校建築常見短柱現象，關於短柱現象之敘述，下列何者正確？",[47,50,53,56,59],{"number":10,"session":48,"stem":49},"114180","圖示之梁構造中 C 為鉸接，不考慮自重影響，在 B 出現微小垂直沉陷時，下列敘述何者…",{"number":10,"session":51,"stem":52},"113190","一般建築結構耐震設計時，下列敘述何者錯誤？",{"number":10,"session":54,"stem":55},"112190","下列有關纜索結構系統的敘述，何者正確？",{"number":10,"session":57,"stem":58},"111180","關於木質構造，下列敘述何者錯誤？",{"number":10,"session":60,"stem":61},"110180","下列有關鋼柱挫屈強度 Pcr 之敘述，何者錯誤？",1791863213882]