外文翻译--日本钢结构桥梁目前现状和发展前景-桥梁设计(编辑修改稿)

外文翻译--日本钢结构桥梁目前现状和发展前景-桥梁设计(编辑修改稿)内容摘要：

important part of the future steel bridge market in Japan . In Japan, many bridges have been constructed to establish an efficient highway work since World War II. Attention has been, however, paid mainly to the construction of safe and standard bridges with, as far as possible, uniform quality with regard to design loads. Until recently, governments could not afford to consider the harmony between the bridges and their surrounding environment. For example, it is very difficult to have a clear and unobstructed view of the beautiful and historically important Osaka Castle due to the highrise buildings and elevated highway bridges. This is an example of the undesirable influence of elevated bridges on their surrounding environment. On the other hand, many drivers plain about the unfortable feeling in driving over some bridges, as a result of big gaps and misalignment at their expansion joints. Many neighborhoods along some superannuated bridges also register plaints with regard to the noise and vibration stemming from existing bridges . 8 Considering these circumstances, the refreshment and recreation of some superannuated bridges is needed because of bridge safety as well as the unfortable influence of the bridges on their surrounding environment. Another example of an unfortable environment can be found where a hospital is located near elevated highway bridges. These tight situations can often be seen in Japan, since it is a mountainous country and has less flat land over which the infrastructure needs to be developed. In this paper, consideration is given to the requirements for a bright future for the Japanese steel bridge industry by carefully analysing recent trends. The state of the art in bridge construction during both the developing era and the fairly developed era, and the considerations towards a bright future in Japanese steel bridge construction could be useful also to various other countries, including, in particular, earthquake prone countries, and for various situations of bridge construction. 2. Recent trends in steel bridge construction in Japan . Construction trend The construction trend of steel bridges in Japan can be summarised as follows: (1) Technological and financial backgrounds in the developing era enabled the acplishment of big projects which led to the construction of large steel bridges. (2) Nowadays, however, the planning for the construction of longspan steel bridges has been almost finished due to serious economical recession. (3) Many steel bridges were constructed during three decades (1960s–80s) to support the quick economical growth in the developing era. (4) However, the number of steel bridges constructed per year has declined to 40% of its peak approximately. (5) The number of constructed RC and PC bridges has remained almost constant from the beginning of 1960 to date. (6) Recently, various kinds of damage have started to occur in many bridges constructed in the decade of the 1960s. (7) After the Hyogoken Nambu Earthquake in 1995, importance has been attached to the seismic design of new bridges and the seismic retrofitting of existing steel bridges, taking into account the ductility of the steel members and structures. (8) Many seismic repair and retrofitting works of bridge piers, bearings and restrainers damaged at the earthquake have been carried out and these works will be pleted in the near future. (9) In the near future, the seismic retrofitting works for longspan steel bridges are due to start. (10) Instead of the construction of large bridges, the retrofitting, strengthening, repair and maintenance of existing steel bridges will bee an important part of the future steel bridge market. (11) During the developing era of Japan, attention was paid mainly to the construction of safe and standard bridges with uniform quality because governments could not afford to consider the harmony between the bridges and their surrounding environment until recently. (12) Nowadays, during the fairly developed era, many existing steel bridges have 9 some problems, such as corrosion of steel members, fatigue cracks in RC slabs, steel decks and steel members due to overweight vehicles and other factors. (13) As a result, many existing bridges require substantial strengthening and repair works. (14) Furthermore, many drivers now plain about the unfortable feeling in driving over some bridges due to big gaps and misalignments at their expansion joints. Many neighborhoods in close proximity to some superannuated bridges also plain about noise and vibration from the bridges. (15) Considering these circumstanc。