中華民國內政部建築研究所中華民國內政部建築研究所

一、研究緣起
內政部已啟動「全國建築物耐震安檢及重建補強-給國人一個安心的家」的政策，全力推動老舊建築物於重建或全面補強的整合或規劃期間，可進行局部性或較快速的階段性補強策略，讓建築物排除軟弱層破壞，降低倒塌風險。因此，為配合前揭政策，著手檢視及發展適用於「階段性補強」的技術研究。
碳纖維強化高分子複合材料(CFRP)包覆補強工法，具有施工容易、施工快速、不佔空間、價格較低與CFRP材料抗拉強度高等特性，可提供有安全疑慮的房子，能快速的進行耐震補強。由國內外相關文獻顯示，對RC柱試體補強工法之研究，多採水平向進行CFRP貼片之貼覆，此亦符合學理上提供水平向之圍束力。惟國內對於RC柱以CFRP貼片補強工法之實務，常見先垂直向再水平向混貼的補強工法，此種包含垂直向之貼覆方式，在既有文獻中亦不多見。因此，本研究將透過結構試驗驗證，以釐清CFRP貼覆方向對RC柱韌性補強效益之疑義，並確認CFRP補強工法施工細部之合理性。
二、研究方法及過程
本研究共規劃ND及NDC等2個系列共計4組試體，分別為試體ND為典型非韌性矩形RC柱，另外NDCH試體係以1層碳纖維水平向貼覆進行補強，試體NDCHH係貼覆2層水平向碳纖維貼片，試體NDCVH則表面先垂直向貼覆1層CFRP貼片，在於其外貼覆地2層水平向之CFRP貼片，NDC系列3組試體斷面之4周角隅，均預製半徑為3公分之圓弧導角。所有試體於試驗前，均無任何裂縫損傷；加載軸力比為20%，且於定軸壓下進行側向加載試驗。
三、重要發現
(一)由試體破壞情形觀察，以CFRP貼片進行韌性補強，可將非韌性配筋RC柱原屬剪力控制之破壞，轉化為於柱端之撓剪破壞主控。
(二)比較試體ND與NDCH試驗結果顯示，若僅於水平向補強1層CFRP貼片（即每平方公尺300克以上的碳纖維），其塑性轉角容量可提升42.9％，因此若進行1層水平向CFRP貼片圍束補強，對柱韌性提升效果是明顯的。
(三)比較試體NDCH與NDCHH試驗結果顯示，將水平向CFRP貼片，由貼覆1層增加為2層，其塑性轉角容量可再提升44.2%，最大側力強度僅再些微增加4.0％。表示RC柱若以水平向CFRP貼片進行圍束補強，對韌性的提升效益，明顯優於對最大側力強度之影響。
(四)比較試體NDCH與NDCVH試驗結果顯示，若NDCH多貼覆1層垂直向CFRP貼片，塑性轉角能力僅提升14％，而最大側力強度僅增加0.7%，此表示多貼覆1層垂直向之CFRP貼片，對柱韌性及最大側力強度之效益均有限。
(五)比較NDCHH與NDCVH試驗結果顯示，當試體同樣貼覆2層CFRP貼片，若2層均為水平方向補強，較1層垂直1層水平方向混貼者，其塑性轉角能力可提升27％，最大側力強度約略增加3.5%，故建議CFRP貼片應採水平方向施工。
四、主要建議事項
立即可行建議－對於RC柱的「韌性」補強效益，若採水平方向貼覆CFRP貼片，將明顯優於採垂直向之貼覆。
主辦機關：建築師公會、結構工程技師公會、土木技師公會
協辦機關：內政部建築研究所
實驗結果顯示，於水平向貼覆碳纖維貼片，可提供柱構件混凝土有較佳的圍束效果，因此對韌性補強效益的提升，明顯優於採垂直向之貼覆方式。國內對於RC柱以CFRP貼片補強工法之實務，常見先垂直向再水平向混貼工法的補強效益，並未優於均以水平向貼覆的方式。
立即可行建議－以CFRP貼片進行柱構件韌性補強，應於全柱貼覆CFRP貼片，避免破壞發生於非預期位置。
主辦機關：建築師公會、結構工程技師公會、土木技師公會
協辦機關：內政部建築研究所
以CFRP貼片進行韌性補強，可能將非韌性配筋（橫向鋼筋量不足者）柱，由屬剪力控制之破壞模式，轉為撓曲破壞主控之情況，故不宜僅於柱端可能發生撓曲塑鉸之範圍，貼覆CFRP貼片。當RC柱試體達極限變形時，若柱斷面採凸角為3公分半徑之導角，以及沿碳纖維方向採20公分的搭接長度，碳纖維貼片應可避免發生非預期之破壞。
立即可行建議－RC柱矩形斷面採凸角半徑為3公分以上之圓弧導角，以及沿碳纖維方向採20公分以上的搭接長度，可避免隅角部及搭接位置之CFRP貼片，發生非預期之破壞。
主辦機關：建築師公會、結構工程技師公會、土木技師公會
協辦機關：內政部建築研究所
RC柱斷面之角隅部，採凸角半徑為3公分以上之圓弧導角，當RC柱達極限破壞時，CFRP貼片並未過早發生因角隅應力集中之斷裂。並且沿CFRP纖維方向採20公分以上的搭接長度，以及沿非CFRP纖維方向採10公分的搭接，亦未發現因纖維搭接長度不足之破壞。

1.Purpose
The Ministry of the Interior has launched the policy of "Buildings Anti-seismic Security Inspection and Reinforcement- a home for the peace of mind". The policy focus on the old buildings in reconstruction or comprehensive reinforcement. For this we adopted and develop a strategy of short-term strengthened before the comprehensive strengthened and rebuilding. During reconstruction or comprehensive strengthened or planning stage, provide local strengthened to avoid weak layer damage and reduce collapse risk by the earthquake.
Carbon fiber reinforced polymer composite (CFRP) strengthened. It has the characteristics of simple construction, short construction period, no space occupation, low cost and high tensile strength of materials. It can quickly provide houses with safety concerns, make the RC column not easy to break, and increase the chance of people's escape. According to the literature, the research of the RC column reinforcement method, the CFRP is applied in multiple horizontal directions. However, The reinforcement method of vertical and then horizontal mixing is common in Taiwan. This type of covering method including vertical direction is rare in existing literature. Therefore, this study will be through structural tests. Discussion on the CFRP cover direction for the RC column toughness reinforcement effect.
2.Method and Steps
This study plan 4 of 2 series specimen including ND and NDC. ND is a typical non-tough rectangular RC column. NDCH specimen is reinforced with 1 layer of CFRP horizontal overlay. NDCHH specimen is reinforced with 2 layer of CFRP horizontal overlay. reinforced with 2 layer of carbon fiber, one is horizontal overlay, other is vertical overlay. All specimens have no crack damage before the test; the loading axial force ratio is 20%, and the lateral loading test was performed under the fixed axial pressure.
3.Main Finding
(1)Observing the failure mode of the specimens. The non-ductility reinforcement (insufficient transverse reinforcement), its failure mode of the original is shear damage control. After using CFRP strengthened, the failure mode can be converted to flexural damage control.
(2)Comparing the results of the specimen ND and the specimen NDCH, they show that one layers of carbon fiber (i.e. 300 g of carbon fiber per square meter) make plastic drift ratio can be increased 42.9 percentage, and the ductility improvement effect is obvious.
(3)Comparing the results of the specimen NDCH and the specimen NDCHH, increase the horizontal CFRP layer from 1 layer to 2 layers make plastic drift ratio can be increased 44.2 percentage, maximum lateral force strength increased only 4.0 percentage. The RC column is horizontally reinforced with CFRP to improve the plastic drift ratio, obviously better than the effect on the maximum lateral force strength.
(4)Comparing the results of the specimen NDCH and the specimen NDCVH, NDCVH posted one layer of vertical CFRP, plastic drift ratio is only increased 14 percentage and the maximum lateral force strength is only increased 0.7 percentage. NDCVH specimen is covered with more than one layer of vertical CFRP, which have limited benefits on column plastic drift ratio and maximum lateral force strength.
(5) When the specimen is also covered with two layers of CFRP, specimen NDCHH plastic drift ratio can be increased 27 percentage and the maximum lateral force strength is increased 3.5 percentage than specimen NDCVH. RC columns are reinforced with CFRP, and the covering should be applied in the horizontal direction.
4.Major suggestion
Immediate adoption suggestion- For the "toughness" reinforcement effect of RC columns, if the CFRP patch is applied horizontally, it will be significantly better than the vertical method.
Major Office：Architects Association, Structural Engineering Technician Association, Association of Civil Engineers
Associate Office：Architecture and Building Research Institute Ministry of Interior
The experimental results show that the application of carbon fiber patches in the horizontal direction can provide better confinement effect for the column member concrete, so the improvement of the toughness reinforcement effect is significantly better than the vertical application method. In the domestic practice of RC columns with CFRP patch reinforcement method, the reinforcement effect of the vertical and then horizontal mixing method is often not better than the method of horizontally covering.
Immediate adoption suggestion- CFRP patches are used to reinforce the column members. CFRP patches should be applied to the entire column to prevent damage from occurring in unexpected locations.
Major Office：Architects Association, Structural Engineering Technician Association, Association of Civil Engineers
Associate Office：Architecture and Building Research Institute Ministry of Interior
CFRP patch for toughness reinforcement may change the non-reinforced (insufficient transverse reinforcement) column from a failure mode controlled by shear force to a situation where the main control is damaged by flexural. Flexural plastic hinge to cover the CFRP patch. When the RC column specimen reaches the limit deformation, if the chamfer angle of radius is 3 cm and a 20 cm overlap length along the direction of the carbon fiber, the carbon fiber patch should avoid unexpected damage.
Immediate adoption suggestion-The corner of the rectangular RC column specimens are chamfer angle of radius is 3 cm and the lap bond (length is 20 cm) was applied along the carbon fibers. CFRP at corners and overlaps can be prevented from being damaged unexpectedly.
Major Office：Architects Association, Structural Engineering Technician Association, Association of Civil Engineers
Associate Office：Architecture and Building Research Institute Ministry of Interior
The corner of the rectangular RC column specimens are chamfer angle of radius is 3 cm. When the RC column specimen reaches the limit deformation, the carbon fiber does not break due to the stress concentration of the corner. Moreover, the lap bond (length is 20 cm) was applied along the carbon fibers, they have no damage by the insufficient bonding of carbon fibers.