铁路钢桥承受的载荷是往复的交变荷载，其主要的破坏形式之一是疲劳和断裂。
The loads on railway steel Bridges are repetitive, the fatigue and fracture are the main reasons that engineering constructions lose their capability.
混凝土腐蚀疲劳破坏是腐蚀介质与交变荷载耦合作用的结果，对其研究目前国内外还仅处于理论探索阶段。
Corrosion fatigue damage of concrete is the coupling action result of corrosion medium and load fatigue, and the study on this has been in the stage of theory search.
部分预应力混凝土梁中的非预应力钢筋在反复运行荷载作用下承受交变应力。
The non—prestressed steel bars in ppc beams endure alternate stress under the repeated service loading.
根据原型结构实测数据的分析，本文把直立结构的挤压冰荷载分为三种不同的模式：准静态冰力、稳态交变冰力以及随机交变冰力。
Based on analysis of the field tests data, crushing ice forces on vertical structures are classified into three modes: quasi static ice force, steady state dynamic ice force and stochastic ice force.
目前在对冰荷载的研究上，主要有极值静冰力和交变冰力两种。
In present research, the extremal ice force and dynamic ice force are the main ice force.
目前在对冰荷载的研究上，主要有极值静冰力和交变冰力两种。
In present research, the extremal ice force and dynamic ice force are the main ice force.
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