[{"data":1,"prerenderedAt":58},["ShallowReactive",2],{"q-114180-arch_structure-3":3},{"question":4,"neighbors":27,"sameNumber":42,"prev":31,"next":34},{"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-114180-801-0102-003","architect","114180",114,"建築結構",3,null,"如圖所示，x 軸為作用力的反覆加載週期數目（N），y 軸為鋼所承受的應力（MPa）大小，若所承受的應力比材料本身的降伏應力小，該圖主要在說明鋼的何種性質？應力（MPa）鋼反覆加載週期數目（N）",{"A":14,"B":15,"C":16,"D":17},"疲勞現象","彈性係數","彈塑性行為","韌性",[19],"A","single",[22],"\u002Fimages\u002Farch-114180-801-0102-003.png","本題考點：鋼材的疲勞性質，也就是「應力–反覆加載次數曲線」（S–N 曲線）的判讀。\n【正解理由】題圖橫軸是反覆加載週期數目、縱軸是鋼所承受的應力，曲線的形態是：施加的應力越高，鋼能撐過的反覆次數越少；應力降到某一水準以後，曲線轉為接近水平。題幹又限定所承受的應力比降伏應力小，代表單獨一次加載並不會讓鋼降伏，破壞是反覆加載使微小裂縫萌生、逐次擴展、最後斷裂所累積出來的結果，這種「低於降伏應力、因反覆加載而破壞」的現象就是疲勞。曲線右段趨於水平的應力水準稱為疲勞限（耐久限），應力低於它時，鋼可承受極多次反覆而不發生疲勞破壞。故選 A。\n【逐項排除】\n(A) 符合。圖的兩個座標軸正好是 S–N 曲線的定義：縱軸應力、橫軸到破壞時的反覆次數；曲線下降段表示應力越大壽命越短，趨平段表示疲勞限，這正是「疲勞現象」要說明的內容。\n(B) 不符。彈性係數是彈性範圍內應力與應變的比值，必須由應力–應變曲線初始直線段的斜率求得；本圖橫軸是反覆次數而不是應變，圖上讀不出任何應變，因此無法說明彈性係數。\n(C) 不符。彈塑性行為描述的是材料超過降伏點後的應力–應變關係（彈性段、降伏平台、應變硬化），前提是應力達到或超過降伏應力；本題明定應力低於降伏應力，且圖軸不是應變，與彈塑性行為無關。\n(D) 不符。韌性是材料破壞前吸收能量的能力，要用應力–應變曲線下的面積或衝擊試驗的吸收能來表示；本圖沒有能量也沒有應變資訊，不能用來說明韌性。\n【演算步驟】本題不需數值運算，判讀程序為：①確認縱軸為應力、橫軸為反覆加載次數，即 S–N 曲線；②曲線隨次數增加而下降，表示應力越高、可承受次數越少；③曲線右段趨平，表示存在疲勞限；④題幹限定應力低於降伏應力，排除與降伏有關的彈塑性行為，得到疲勞現象。\n【記憶點】橫軸是「反覆次數」的應力曲線就是疲勞；應力低於降伏照樣會壞，曲線趨平處是疲勞限。",545,1,true,[28,30,33,36,39],{"number":25,"session":7,"stem":29},"下列何者為材料彈性模數 E（modulus of elasticity）之單位？",{"number":31,"session":7,"stem":32},2,"下列有關混凝土性質的敘述，何者錯誤？",{"number":34,"session":7,"stem":35},4,"一長度為 2 m 圓棒，直徑為 30 mm，彈性模數為 70 GPa，波松比（Poi…",{"number":37,"session":7,"stem":38},5,"關於圓球薄殼結構，下列敘述何者錯誤？",{"number":40,"session":7,"stem":41},6,"關於薄膜結構，下列敘述何者正確？",[43,46,49,52,55],{"number":10,"session":44,"stem":45},"113190","關於薄殼結構，下列敘述何者錯誤？",{"number":10,"session":47,"stem":48},"112190","下列敘述何者正確？①在同一場地震事件下，各地區震度相同，地震規模相異 ②某次地震 A…",{"number":10,"session":50,"stem":51},"111180","下列混凝土抗壓強度：甲、3000 psi，乙、280 kgf\u002Fcm2，丙、30 MP…",{"number":10,"session":53,"stem":54},"110180","高樓結構常以帶狀桁架（belt truss）配置在具有結構核之系統，其目的為何？",{"number":10,"session":56,"stem":57},"109180","國外高樓結構系統中，常用內部 RC 核心牆筒及外周部抗彎矩構架組成，而內外之間則以小…",1791863193926]