2019-12-12 08:08:16来源:励志吧0次阅读



2014 Freudenthal奖获奖词

Jie Li, Ph.D.

Distinguished Professor, Tongji University

“For the development of the probability density evolution methods and contributions to seismic reliability based design of large scale civil infrastructure systems”



Thanks a lot, everyone, ladies and gentlemen.

When I walked around the campus of Chongqing University in 1982, I never imaged that one of the winners of Freudenthal medal would be me. On this special occasion, I would like to express my sincere thanks to the award community of ASCE, and I would like to express my sincere thanks to all of my friends in the world, my colleagues in Tongji University, my great associates and students in my group, and of course may be the same important of my life, my wife- Min Xie, there, please. Without their helps and supports, I would not stand here.

On this special occasion, I would like to beg you a pardon for giving me some time to say a story, a little bit story about myself. As I mentioned, you know, I start my academic career in Chongqing University, which locates in the south-west part of China and it is a very beautiful mountain city. In that time, I pursued master degree under the supervision of Professor Dezhong Ding, who graduated from Cornell University in 1930s. I still remember that in autumn 1983, one day afternoon Prof. Ding knocked at the door of my dormitory and said to me “please come to check your beam, may be some wrong in your tested beam.” Since in that time, you know, my professor seldom came to my room, so I rushed very quickly to the lab and checked very details of my tested beams. Finally I found one error- a little error on the tested beam: The designed space of stirrup is 5 centimeters but the real is 7. That was a very little error. I corrected the error and thought the experiment must be very successful. Really, after three months, I got very successful experimental results. But from here – a natural result, I met a very huge problem. That means if I used an identified parameter for every beams, I could get very little errors between the experimental results and theoretical results. But if I wanted to get a set of unifiedparameters for all the tested beams, the error would increase quilt large. So I knew I met a problem firstly, that was just the randomness.

From then to now, the randomness has spoiled my life: What is the randomness? Where is the resource of randomness? It really exists a stochastic rule? These problems always occupied my mind in my life. It was only ten years later, when I involved in the stochastic modeling of structures under the supervision of Professor Roberts in Sussex University, I first realized that the physical relationship is the basis for the stochastic schemes, which was the first step that we got the PDEM eight years later.

In my opinion, you know, we are living in a world full of uncertainties. Most of people like to use deterministic models to simulate the reality. But some other people think there are two worlds: deterministic world and stochastic world. In my opinion, most important things is, what is the bridge connecting these two worlds. The PDEM could answer the question. Actually, the randomness does not change the physical rule, so the probabilistic structures of a stochastic system will be governed by the physical mechanism of the system. I think this is a new idea about our living world.

In 1994, when I was living in England, I had a talk with Prof. Roberts. In that time I was very excited in our new advancement of stochastic modeling of systems. However, Prof. Roberts told me ‘It is only a start’. From then to now, the words always appear in my mind. Really, it is only a start. With your help and your interesting, I believe, the PDEM could be used in a broader of area. I hope so


Thanks a lot. Thank you.




在这个特殊的场合,请允许给我一点时间向大家讲一段故事,一段关于我自己的故事。诚如我刚才提到的,我的学术生涯是从重庆大学开始的。重庆大学位于中国西南部,是一座以山城闻名的城市。当时,我跟随我的导师丁得忠先生攻读硕士学位。丁先生在上世纪30年代毕业于美国康乃尔大学(Cornell University)。我依然记得,1983年秋天的一天下午,丁先生专程来到我的寝室告诉我:“请去检查一下你的试验梁,可能有问题”。你知道,在当时先生是很少到学生宿舍来的。所以我很快奔入试验室、仔细检查每一个细节。最终,我发现了一个失误(这个在今天的试验中被认为是可以忽略的误差):某两根箍筋的设计间距是5cm,而实际间距是7cm。尽管是可以忽略的误差,但我还是仔细修正了这个失误,当时我想,我的试验必然会成功。的确,三个月后我获得了非常好的试验结果。然而,从这样一个试验、一个非常普通的试验,我却碰到了很大的问题:如果我对每一个梁分别采用识别的参数,试验与理论分析之间的误差会非常小;但如果对所有梁采用同一组参数,误差将会变得相当大。我知道,我第一次遇到了真正的问题:随机性。