【正文】 70年代，在歐洲涌現(xiàn)了大量的混凝土結(jié)構(gòu)的橋梁，在那個(gè)時(shí)候，這種構(gòu)造被視為是免于維 修的。但它仍然被用于大跨徑橋梁和鐵路用橋，如今，隨著英國正在進(jìn)行的高速公路拓寬計(jì)劃的實(shí)施，這種橋梁又重新受到了人們的青睞。 特別需要關(guān)注的是后張力法施工的橋梁的完整性。因?yàn)檫@ 種橋梁可能會(huì)毫無預(yù)兆地出現(xiàn)脆性斷裂，后張法鋼絞線在預(yù)制段搭接部位的防腐工作是影響這種類型橋梁長期穩(wěn)定性的主要因素。 橋梁上部結(jié)構(gòu)由空心梯形混凝土箱梁組成。 大橋中跨和南部引橋跨徑均采用后張法裝配式預(yù)制結(jié)構(gòu)，這些后張法預(yù)制構(gòu)件構(gòu)件包括五種類型的預(yù)應(yīng)力張拉措施。 空心箱梁內(nèi)部 300mm 深度內(nèi)雨水的滲透情況。 現(xiàn)澆混凝土表面大片的剝落部位和暴露在外的生銹的加強(qiáng)筋。 檢測和評估的結(jié)論 根據(jù)檢測和評估，仍然存在著一個(gè)主要的可疑因素，它就是埋藏在構(gòu)件里面的預(yù)應(yīng)力鋼絞線、電纜或桿件，雖然從結(jié)構(gòu)原 理的角度進(jìn)行分析，這些假定均不成立。 修理不合格防水材料和混凝土表面的瑕疵。一個(gè)標(biāo)準(zhǔn)的鉸接縫橫端面，主梁內(nèi)部的24 根鋼筋束很難被檢測到，因?yàn)槌算q接縫外，鋼絞線在施加預(yù)應(yīng)力之后又被 現(xiàn)澆的混凝土所包裹。 為了對比，選定了 10 個(gè)觀測孔，小孔是垂直向下鉆進(jìn)導(dǎo)管。結(jié)果顯示，在超過 60%的案例中，雷達(dá)的檢測是準(zhǔn)確的。在少數(shù)幾個(gè)案例中，在沙漿表面能明顯地看到預(yù)應(yīng)力鋼絞線，但沒有跡象表明有水滲透了進(jìn)去。最高的頻率能帶來最好的分辯率，但會(huì)減小其在混凝土中的穿透深度。這種轉(zhuǎn)換是使用一種 16 位的模擬信號變流器，它能使數(shù)據(jù)獲得相當(dāng)高的分辨率，以便用于后續(xù)的數(shù)據(jù)處理。 沿著軌跡做特別的標(biāo)記，再通過記錄元件或天線把這個(gè)軌跡描述下來。除了 這些能變換顏色的設(shè)備外，還可能使用用來過濾水平線和豎直線的特殊程序。 結(jié)論 一個(gè)關(guān)于橋梁研究平 臺(tái)的雛形已經(jīng)在歐洲誕生。 Bridge research in Europe A brief outline is given of the development of the European Union, together with the research platform in Europe. The special case of posttensioned bridges in the UK is discussed. In order to illustrate the type of European research being undertaken, an example is given from the University of Edinburgh portfolio: relating to the identification of voids in posttensioned concrete bridges using digital impulse radar. Introduction The challenge in any research arena is to harness the findings of different research groups to identify a coherent mass of data, which enables research and practice to be better focused. A particular challenge exists with respect to Europe where language barriers are inevitably very significant. The European Community was formed in the 1960s based upon a political will within continental Europe to avoid the European civil wars, which developed into World War 2 from 1939 to 1945. The strong political motivation formed the original munity of which Britain was not a member. Many of the continental countries saw Britain’s interest as being purely economic. The 1970s saw Britain joining what was then the European Economic Community (EEC) and the 1990s has seen the widening of the munity to a European Union, EU, with certain political goals together with the objective of a mon European currency. Notwithstanding these financial and political developments, civil engineering and bridge engineering in particular have found great difficulty in forming any kind of mon thread. Indeed the educational systems for University training are quite different between Britain and the European continental countries. The formation of the EU funding schemes —. Socrates, Brite Euram and other programs have helped significantly. The Socrates scheme is based upon the exchange of students between Universities in different member states. The Brite Euram scheme has involved technical research grants given to consortia of academics and industrial partners within a number of the states— a Brite Euram bid would normally be led by an industrialist. In terms of dissemination of knowledge, two quite different strands appear to have emerged. The UK and the USA have concentrated primarily upon disseminating basic research in refereed journal publications: ASCE, ICE and other journals. Whereas the continental Europeans have frequently disseminated basic research at conferences where the circulation of the proceedings is restricted. Additionally, language barriers have proved to be very difficult to break down. In countries where English is a strong second language there has been enthusiastic participation in international conferences based within continental Europe —. Germany, Italy, Belgium, The Netherlands and Switzerland. However, countries where English is not a strong second language have been hesitant participants }—. France. European research Examples of research relating to bridges in Europe can be divided into three types of structure: Masonry arch bridges Britain has the largest stock of masonry arch bridges. In certain regions of the UK up to 60% of the road bridges are historic stone masonry arch br