[{"data":1,"prerenderedAt":61},["ShallowReactive",2],{"q-110180-arch_structure-37":3},{"question":4,"neighbors":26,"sameNumber":45,"prev":34,"next":37},{"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":22,"withheld":11,"deepChars":23,"freq":24,"indexable":25},"arch-110180-801-0102-037","architect","110180",110,"建築結構",37,null,"根據鋼筋混凝土「單筋矩形梁」之斷面極限彎矩強度分析，若鋼筋混凝土梁斷面在「平衡應變狀態」之鋼筋量 Asb = 20.28 cm2 時，則當拉力鋼筋量 As 為下列何者時，在極限狀態下拉力鋼筋已降伏？",{"A":14,"B":15,"C":16,"D":17},"4 根 D22 鋼筋","4 根 D29 鋼筋","5 根 D25 鋼筋","8 根 D19 鋼筋",[19],"A","single",[],"本題考點：鋼筋混凝土單筋矩形梁的破壞模式判別——拉力鋼筋量 As 小於平衡鋼筋量 Asb 時，極限狀態下拉力鋼筋已降伏（拉力控制、韌性破壞）；As 大於 Asb 時，混凝土先壓碎而鋼筋尚未降伏（壓力控制、脆性破壞）。\n【正解理由】「平衡應變狀態」是指混凝土最外緣壓應變達到極限壓應變的同時，拉力鋼筋恰好達到降伏應變；此時的鋼筋量就是 Asb = 20.28 cm²。鋼筋量比 Asb 少時，拉力合力較小，所需的混凝土壓力區較淺，中性軸上移，混凝土壓碎時鋼筋應變已超過降伏應變，鋼筋已降伏。所以只要找出 As \u003C 20.28 cm² 的選項。以鋼筋號數作為標稱直徑的近似值（mm），計算各組鋼筋面積 As = n × π d² \u002F 4：4 根 D22 為 4 × 3.1416 × (2.2 cm)² \u002F 4 = 15.21 cm²，小於 20.28 cm²；其餘三組都大於 20.28 cm²。故選 A。\n【逐項排除】\n(A) 4 根 D22 鋼筋：As = 15.21 cm² 小於 Asb = 20.28 cm²，屬低於平衡鋼筋量的梁，極限狀態時拉力鋼筋已降伏，符合題目所問。\n(B) 4 根 D29 鋼筋：As = 4 × 3.1416 × (2.9 cm)² \u002F 4 = 26.42 cm²，大於 Asb，屬超量配筋，混凝土先達極限壓應變，鋼筋應變尚未達降伏應變，鋼筋未降伏。要讓鋼筋降伏，鋼筋量必須降到 Asb 以下。\n(C) 5 根 D25 鋼筋：As = 5 × 3.1416 × (2.5 cm)² \u002F 4 = 24.54 cm²，大於 Asb，同樣是混凝土先壓碎、鋼筋未降伏的壓力控制破壞，不符題意。\n(D) 8 根 D19 鋼筋：單根直徑最小，但根數多，As = 8 × 3.1416 × (1.9 cm)² \u002F 4 = 22.68 cm²，仍大於 Asb。判斷依據是總鋼筋面積，不是單根粗細，所以鋼筋未降伏，不符題意。\n【演算步驟】\n判別式：As \u003C Asb → 極限狀態下拉力鋼筋已降伏；As > Asb → 鋼筋未降伏\n鋼筋面積：As = n × π × d² \u002F 4（d 以號數換算為 cm）\n(A) 4 根 D22：As = 4 × 3.1416 × 2.2 cm × 2.2 cm \u002F 4 = 15.21 cm² \u003C 20.28 cm²\n(B) 4 根 D29：As = 4 × 3.1416 × 2.9 cm × 2.9 cm \u002F 4 = 26.42 cm² > 20.28 cm²\n(C) 5 根 D25：As = 5 × 3.1416 × 2.5 cm × 2.5 cm \u002F 4 = 24.54 cm² > 20.28 cm²\n(D) 8 根 D19：As = 8 × 3.1416 × 1.9 cm × 1.9 cm \u002F 4 = 22.68 cm² > 20.28 cm²\n結果：只有 4 根 D22 的鋼筋量小於平衡鋼筋量，極限狀態下拉力鋼筋已降伏。\n【記憶點】鋼筋量少於平衡鋼筋量，鋼筋先降伏、破壞有預警；多於平衡鋼筋量，混凝土先壓碎、鋼筋沒降伏——比的是總面積不是單根粗細。",713,1,true,[27,30,33,36,39,42],{"number":28,"session":7,"stem":29},34,"圖中構架 ABCD 之 A 點固端彎矩為何？ 3m 2 kN 4m 10 kN-m …",{"number":31,"session":7,"stem":32},35,"下圖的結構中，關於支承 A、B 點之反力的敘述何者錯誤？ 60°",{"number":34,"session":7,"stem":35},36,"圖示結構 A、C 為鉸端，B 為鉸接，則 A 點處水平反力為何？ 60 kN 9m …",{"number":37,"session":7,"stem":38},38,"混凝土構架的耐震撓曲構材縱向鋼筋在梁柱交接面（梁端）及其他可能產生塑鉸位置，其壓力鋼…",{"number":40,"session":7,"stem":41},39,"鋼結構梁柱接頭中強度減弱型接頭（如下圖 A 之圓弧切削式接頭）以及強度增強型接頭（如…",{"number":43,"session":7,"stem":44},40,"對於特殊抗彎矩構架系統建築物採用鋼筋混凝土構造或鋼構造，在一般情況下，下列何者在兩種…",[46,49,52,55,58],{"number":10,"session":47,"stem":48},"114180","關於鋼筋混凝土（RC）、鋼骨（SS）、與鋼骨鋼筋混凝土（SRC）結構的比較，下列敘述…",{"number":10,"session":50,"stem":51},"113190","於體育館大跨度空間的結構設計中，下列何種結構系統最不符合結構效益？",{"number":10,"session":53,"stem":54},"112190","下列何者須考量材料異向性對結構力學特性的影響？",{"number":10,"session":56,"stem":57},"111180","下列何項建築結構規劃較無法達到二氧化碳減量？①結構合理化：避免平面不規則與立面不規則…",{"number":10,"session":59,"stem":60},"109180","關於挫屈束制支撐（BRB）之敘述，下列何者錯誤？",1791863205126]