碳纖棒用於預力構件之研究(2)

Abstract

台灣地區多河川山岳，平原或盆地之土地開發密集，為連結各各城鎮，並節省用地，許多地區道路路堤改採橋梁形式興建，使得公路之構造多朝橋梁方式興建。探究台灣地區橋梁損害的主要因素，可分為結構面與材料面二大方面。結構上是受到台灣地處環太平洋地震帶之影響，所有的結構設計均需考慮到耐震設計，因此不僅橋梁耐震係數已歷數次不斷的修正提高，各項減震、隔震系統之研究發展也愈趨完備；材料上則因台灣特有之海島型氣候，無論是混凝土抑或鋼材，均易受海風、濕度、空氣中含氯離子及硫化物等因素，加速混凝土的鹽害、中性化，及鋼材的腐蝕。為減少材料的老劣化程度，目前的防治機制均是以改變混凝土之成分配比，或是添加腐蝕抑制劑摻料於混凝土中，以增加混凝土之強度、水密性、耐候性等，從而有高性能混凝土、活性粉混凝土之研發。然而對RC結構中的另一關鍵性材料-鋼筋及預力鋼絞線，現在所使用的鋼材，有重量重、製造時耗能量、產生污染及易鏽蝕等等的缺點，而以鏽蝕問題最為嚴重，卻僅能由表面作防鏽處理，難以根治鋼材易受鏽蝕的最大危害。鋼材鏽蝕問題會降低RC及PC 構造物的承載能力，最嚴重可導致對人員的生命及財產產生威脅；因此各種預防鋼材鏽蝕的方法正在廣泛的研究或使用中。 如今一項耐腐蝕、重量輕、施工方便，且抗拉強度更高達鋼筋四倍的新材料-複合材料筋（Fiber Reinforced Plastics Rebar, FRP Rebar）已被開發。由於FRP的絕佳材料特性，最早是被應用在環境嚴苛的太空飛行物中，其後隨著國防工業的技術移轉至民生工業，遊艇外殼、高爾夫球桿、自行車架、浴缸、化學儲存槽等等，各項應用FRP製成的器具，早已融入一般家庭的生活中。雖然土木工程引進FRP為時未久，但包含台灣在內一些地震頻繁的國家，如美國、日本、大陸，都已積極進行許多以FRP應用在RC結構之相關研究，尤其在FRP貼片補強方面，更是已有大量的實際案例以驗證其補強RC橋梁之梁、版、柱的成效。因此在可預見的將來，如能在一些飽受侵蝕危害的區域，如跨海、跨河橋梁，利用FRP Rebar 取代傳統的鋼筋、預力鋼腱，定能免除鋼筋及鋼絞線遭受鏽蝕的疑慮，以有效的延長橋梁的使用壽命；為了防治鋼筋鏽蝕問題，FRP 製品確實為第一選擇。 本研究計畫即是針對以碳纖維高分子複合材料（Carbon Fiber Reinforced Plastics, CFRP）製成之碳纖維棒（CFRP Rebar）及碳纖維絞線，透過國內外文獻規範蒐整、材料及構件試驗、構件行為分析等，進行一系列之材料性質、製程、構件行為，及利用CFRP製品來替代現有鋼筋及預力鋼絞線等研究，期能明確瞭解碳纖維製品的各項物理、化學性質，及其與混凝土結合後的複合構件行為模式，以建立本土性的材料規範及設計流程與公式，從而奠定碳纖維製品應用於橋梁工程之基礎。

Taiwan is mountainous and has many rivers. The remain planes are small and are crowded with residents and factories. It is rather difficult for infrastructure construction in this area due to limitation on acquiring the land. Therefore, highways are moving toward mountain area. The bridges are then necessary for passing through this area. In addition, Taiwan is subjected to many earthquakes. The design of bridges needs to consider this effect and the reinforcement is substantially increased which in turn increase the dead load of the structure. Taiwan is also surrounded by sea, which has a pronounced effect on the durability of structures. Steel is vulnerable to chloride ion and sulfate attack. Though many measures are available to fight against corrosion, these methods are either very expensive or not suitable for in-situ construction. A new material is to be introduced for this durability issue. It is called FRP, or fiber reinforced plastics. It has been used in Europe and US. FRP had been used widely in other applications, such as boat, airplane, vehicle, etc. It is durable, light weight, and corrosion free. It can replace traditional reinforcing bars and prestressing wires for longer life span and less maintenance cost. This study will use the CFRP for this purpose. The geometric shapes, % content of CFRP, anchorage of CFRP will be studied. The products will be then cast into concrete to study the behavior of RC and PC members made of CFRP bars and wires as compared to traditional reinforcements. The results will be used to justify the feasibility of the use of CFRP in infrastructures and relevant design equations will also be developed.