南方澳跨港大橋斷橋是工程界的羞恥.

南方澳跨港大橋斷橋;政府專家學者一致指稱為鋼索或錨固處鏽蝕造成.

非也.

觀察斷橋前的橋中心已嚴重下沉,代表橋板結構(預力系統已失效)趨近破壞.天災稻草只是推動橋斷的插曲.橋版失去預力,結構自重完全轉移至吊索鋼拱,剪斷支撐,橋毀.

黴體的報導代表台灣全島都混得厲害,不思災害的根源,在參加搶答拿獎金.

公路監理單位對道路橋梁的限荷不管制,道路會一直填補,橋梁會不斷坍塌.事故後的檢討,若已設定目標,則失去鑑往知來,主題將隨時間模糊.專家’學者的口頭禪是訂定SOP(standard operating procedure),SOP的實用是結合理論與實務的,也必須與時更新.

Tied-arch bridge的設計及解說本身是難懂的；中文翻譯應該很難達意，稱玄樑繫索橋或許恰當；因為玄就是那連續節塊樑.可以承擔大部設計載重，吊索及拱分擔某些活載.在無活載時橋面版垮距中點是拱起的.

針對橋樑設計功能特性必需有效的公路監理。本案是橋樑常期超荷.設計時若有個後續監測管理合約,對中間節塊設個沉陷點、吊索設個應變計，定時監測，橋的健康得以確保.簡單的、經濟的方式，沒有執行.代表專家、學者都不任份，就是沒務實、不安份.基礎建設是攸關經世濟民的,專心盡心就會有成果.

附錄:摘自維基百科,含玄樑繫索橋示意圖.

Tied-arch bridge

A tied-arch bridge is an arch bridge in which the outward-directed horizontal forces of the arch(es) are borne as tension by a chord tying the arch ends, rather than by the ground or the bridge foundations. This strengthened chord may be the deck structure itself or consist of separate, deck-independent tie-rods.

Thrusts downwards on a tied-arch bridge deck are translated, as tension, by vertical ties between the deck and the arch, tending to flatten it and thereby to push its tips outward into the abutments, like for other arch bridges. However, in a tied-arch or bowstring bridge, these movements are restrained not by the abutments but by the strengthened chord, which ties these tips together, taking the thrusts as tension, rather like the string of a bow that is being flattened. Therefore, the design is also called a bowstring-arch or bowstring-girder bridge .

The elimination of horizontal forces at the abutments allows tied-arch bridges to be constructed with less robust foundations; thus they can be situated atop elevated piers or in areas of unstable soil .

addition, since they do not depend on horizontal compression forces for their integrity, tied-arch bridges can be prefabricated offsite, and subsequently floated, hauled or lifted into place. Notable bridges of this type include the Fremont Bridge in Portland, Oregon as well as the first "computer designed" bridge of this type the Fort Pitt Bridge in Pittsburgh, Pennsylvania .

Both the tied-arch bridge and the self-anchored suspension bridge place only vertical loads on the anchorage, and so are suitable where large horizontal forces are difficult to anchor.

Issues

In a 1978 advisory issued by the Federal Highway Administration (FHWA), the FHWA noted that tied-arch bridges are susceptible to problems caused by poor welds at the connection between the arch rib and the tie girders, and at the connection between the arch and vertical ties. In addition, problems with electroslag welds , while not isolated to tied-arch bridges, resulted in costly, time-consuming and inconveniencing repairs. The structure as a whole was described as nonredundant ; failure of either of the two tie girders would result in failure of the entire structure.

Tied-arch bridge

A tied-arch bridge is an arch bridge in which the outward-directed horizontal forces of the arch(es) are borne as tension by a chord tying the arch ends, rather than by the ground or the bridge foundations. This strengthened chord may be the deck structure itself or consist of separate, deck-independent tie-rods.

Thrusts downwards on a tied-arch bridge deck are translated, as tension, by vertical ties between the deck and the arch, tending to flatten it and thereby to push its tips outward into the abutments, like for other arch bridges. However, in a tied-arch or bowstring bridge, these movements are restrained not by the abutments but by the strengthened chord, which ties these tips together, taking the thrusts as tension, rather like the string of a bow that is being flattened. Therefore, the design is also called a bowstring-arch or bowstring-girder bridge .

The elimination of horizontal forces at the abutments allows tied-arch bridges to be constructed with less robust foundations; thus they can be situated atop elevated piers or in areas of unstable soil .

addition, since they do not depend on horizontal compression forces for their integrity, tied-arch bridges can be prefabricated offsite, and subsequently floated, hauled or lifted into place. Notable bridges of this type include the Fremont Bridge in Portland, Oregon as well as the first "computer designed" bridge of this type the Fort Pitt Bridge in Pittsburgh, Pennsylvania . 

Both the tied-arch bridge and the self-anchored suspension bridge place only vertical loads on the anchorage, and so are suitable where large horizontal forces are difficult to anchor.

Issues

In a 1978 advisory issued by the Federal Highway Administration (FHWA), the FHWA noted that tied-arch bridges are susceptible to problems caused by poor welds at the connection between the arch rib and the tie girders, and at the connection between the arch and vertical ties. In addition, problems with electroslag welds , while not isolated to tied-arch bridges, resulted in costly, time-consuming and inconveniencing repairs. The structure as a whole was described as nonredundant ; failure of either of the two tie girders would result in failure of the entire structure.

This strengthened chord may be the deck structure itself or consist of separate, deck-independent tie-rods

failure of either of the two tie girders would result in failure of the entire structure.