Study on estimation of Fatigue Life in Marine Concrete Structure and it's Application to Limit State Design

海工混凝土结构疲劳寿命估算及其在极限状态设计中的应用研究

基本信息

批准号：
63550352
负责人：
INOUE Shoichi
金额：
$ 1.47万
依托单位：
Tottori University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1988
资助国家：
日本
起止时间：
1988 至 1989
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-63550352/
关键词：
Fatigue test S-N curve Fatigue life Fatigue strength Flexural failure Shear failure Web reinforcement Marine concrete structure 鉄筋コンクリ-ト S-N線図疲労寿命予測コンクリ-ト標準示方書疲労限界状態設計法

项目摘要

In order to investigate the fatigue life of plain concrete and reinforced concrete structures in marine environment, several kinds of fatigue tests were conducted. they were: the constant-amplitude fatigue test, variable load fatigue test and the random load fatigue test in which the shape of the maximum stress level for the random repeated load was set to fit the exponential distribution. from the experimental results for the plain concrete tested in air, it can be concluded as follows. (1) Miner's rule may possibly be a applied to predict the fatigue life under varying repeated load. (2) The variable load fatigue test can be used to simulate the fatigue test Under random load.Next, the fatigue characteristics of reinforced concrete beam in fresh water was investigated. It became clear from these test that (1) The fatigue strength at arbitrary cycles, including 2X10^6 cycles for the beam tested in water was smaller by 15-25% compared to that in air. The failure pattern of a reinforced concrete beam tested in water occurred as a shear failure but as flexural failure in air. At the same upper load level, the fatigue life of the beam with web reinforcement was approximately 100 times that of the beam without it. The flexural crack width of the specimen in water was lower than that exposed to air. At the same upper load level, however, the deflection and the rate of propagation of the diagonal crack were larger in air.Lastly, the flexural fatigue characteristics of reinforced concrete beam which the only bending span of the beam was enclosed in a plastic water jacket containing fresh water was investigated.The agreement between observed and calculated fatigue life according to Part I of JSCE's Concrete Standard Specification for Design and Construction of Concrete Structure was not satisfactory. The tentative equation to estimate the fatigue life with a high accuracy was proposed.

为了研究海洋环境中普通混凝土和钢筋混凝土结构的疲劳寿命，进行了多种疲劳试验。它们是：等幅疲劳试验、变载荷疲劳试验和随机载荷疲劳试验，其中随机重复载荷的最大应力水平的形状被设置为符合指数分布。根据在空气中测试素混凝土的实验结果，可以得出以下结论。 (1) 米纳法则可用于预测不同重复载荷下的疲劳寿命。 (2)变载荷疲劳试验可以模拟随机载荷下的疲劳试验。接下来，研究了淡水中钢筋混凝土梁的疲劳特性。从这些测试中可以清楚地看出，（1）在任意循环（包括2X10^6循环）下，在水中测试的梁的疲劳强度比在空气中小15-25%。在水中测试的钢筋混凝土梁的破坏模式为剪切破坏，但在空气中为弯曲破坏。在相同的上荷载水平下，有腹筋的梁的疲劳寿命约为无腹筋梁的100倍。水中试样的弯曲裂纹宽度小于暴露在空气中的试样。然而，在相同的上荷载水平下，空气中的挠度和对角裂缝的扩展速率更大。最后，梁的唯一弯曲跨度被封闭在塑料水套中的钢筋混凝土梁的弯曲疲劳特性根据JSCE《混凝土结构设计和施工混凝土标准规范》第一部分，观察到的疲劳寿命与计算得出的疲劳寿命之间的一致性并不令人满意。提出了高精度估计疲劳寿命的初步方程。