Abstract In this paper, consideration is given on recent trends in, steel bridge construction in Japan. As far as recent trends are concerned, it is observed that the construction of long and big steel bridges has practically been completed. Consequently, the focus of recent main works is the maintenance of superannuated (averaged) bridges and the seismic retrofitting of existing bridges. The refreshment and regeneration of some superannuated bridges is also needed recently in order to mitigate the uncomfortable influence of these bridges on their surrounding environment. For this purpose, maintenance and retrofitting works should be economically reasonable jobs. The necessity and importance of these works should be understood by the nation through retrofitting existing bridges against disasters and mitigating the unfavorable influence of bridge structures on the bridge environment on the basis of the code of ethics for civil engineers promulgated by JSCE. Moreover, bridge engineers should seek better social status and the bridge engineering field should become attractive to young students who will bear the future of this field.

摘要： 在本文中，探討了日本鋼橋建筑的最近發(fā)展趨向。一提到最近趨向，我們就會發(fā)現(xiàn)長和大的鋼橋建設(shè)實(shí)際已經(jīng)完成了。于是最近主要工作焦點(diǎn)是老化橋梁和現(xiàn)有橋梁的地震改型維護(hù)。為了緩和一些老化橋梁對他們周圍的環(huán)境產(chǎn)生不利的影響對這些橋梁進(jìn)行恢復(fù)和重建是由必要的。為此，維護(hù)和改型工作應(yīng)該是經(jīng)濟(jì)合理的工作。國家應(yīng)該以JSCE公布的土木工程師工程規(guī)范為基礎(chǔ)來改型現(xiàn)有的橋梁，使這些橋梁能夠抵御災(zāi)害和緩和橋梁對周圍環(huán)境的不利影響，以此來了解這些工作的必要性和重要性。而且，橋梁工程師應(yīng)該尋求更好的社會地位，并且橋梁工程學(xué)領(lǐng)域應(yīng)該對將承擔(dān)未來這個(gè)領(lǐng)域的青年學(xué)生變得更有吸引力。
1.1 建筑趨向
在日本，在二十世紀(jì)六十年代至八十年代密集的修建了許多橋梁，在經(jīng)濟(jì)高速發(fā)展時(shí)期，每年修建的橋梁數(shù)量減少到全部最高數(shù)量的一半。更特殊的是，到六十年代下半期，剛橋梁產(chǎn)業(yè)到達(dá)了黃金時(shí)代。盡管RC橋梁和PC橋梁的數(shù)量從二十世紀(jì)六十年代初到現(xiàn)在幾乎保持恒定，然而最新數(shù)據(jù)表明，最近修建的鋼橋數(shù)量下降到大約最高量的百分之四十。
把許多橋梁的構(gòu)筑看作重要基礎(chǔ)設(shè)施之一后，橋梁就主要修建在直接需要的地方。最近，我們觀察到六十年代修建的許多橋梁上都發(fā)生了各種各樣的災(zāi)害。
尤其是通過對由1995年發(fā)生的Hyogo-ken Nambu地震造成的鋼結(jié)構(gòu)的破壞的調(diào)查，我們知道新橋的抗震設(shè)計(jì)和現(xiàn)有鋼橋的抗震改型是非常重要的，目的是運(yùn)用鋼橋構(gòu)件和結(jié)構(gòu)的延展性。許多橋梁修理和結(jié)構(gòu)的地震改型工作由于地震的發(fā)生而被破壞，但是這些工作在不久的將來歸于完成。鋼橋中損壞的部分主要分為橋墩、承力構(gòu)件和保護(hù)橋梁不倒