第三十三卷第三期 (期別131) (107年)

作者:

第三十三卷第三期 (期別131) (107年)

標題鋼筋混凝土圓形柱橫向鋼筋圍束效果之探討
作者李台光、陳正誠
關鍵字鋼筋混凝土圓形柱、橫向鋼筋、圍束效果
摘要本研究完成8支大尺寸鋼筋混凝土圓形柱試體之反復側向載重試驗，共規劃R、S33、S17 及D33 等4 個系列，以箍筋、繫筋總圍束力維持固定為原則，箍筋之圍束力以箍筋2 倍的斷面積與標稱降伏強度之乘積計算，而對於十字型及井字型配置之繫筋，分別以1 根及2 根繫筋斷面積與標稱降伏強度之乘積，計算繫筋之圍束力，探討井字型及十字型等2 種繫筋於圍束柱混凝土的可行性及有效性。研究結果顯示：(1)含十字型及井字型組合繫筋之鋼筋混凝土圓形柱，其耐震性能與側力方向具有某種關聯性，但並不顯著。故圓柱繫筋施工時應不需要特別旋轉或是調整十字型及井字型組合繫筋之方向或指定方向。(2)以本研究圍束力之定義，在相同總圍束力下，圓箍筋的圍束效果優於十字型及井字型配置之組合繫筋，另十字型繫筋比井字型繫筋圍束效果稍佳，組合繫筋之圓箍筋等效圍束力折減之計算，與繫筋配置形式及圍束力比有關，尚需後續進一步研究釐清。
TitleThe confinement effectiveness of transverse reinforcement in circular reinforced concrete columns
AuthorTai-Kuang Lee, Cheng-Cheng Chen
KeywordsCircular RC Columns, Transverse Reinforcement, Confinement Effectiveness
AbstractIn this study, a lateral cyclic load test was conducted on eight specimens of large-sized circular reinforced concrete (RC) columns to investigate the confinement effectiveness of circular ties and lap-spliced crossties. Totally, there are four series of specimens including R, S33, S17 and D33 constructed and tested. In single-cross crossties, the confining force of transverse reinforcement is calculated by adding the confinement effectiveness of one crosstie cross-sectional area. On the other hand, in double-cross crossties, the confining force of transverse reinforcement is calculated by adding the confinement effectiveness of two crosstie cross-sectional areas. The research results are presented as follows: (a) The seismic performance of circular RC columns with single-cross and double-cross lap-spliced crosstie correlates with the lateral loading direction. But its influence is not significant (b) The confinement effectiveness of circular tie is better than that of single-cross and double-cross lap-spliced crosstie. The reduction influence of lap-spliced crossties depends upon crosstie layout and the confinement force ratio. More details need further studies.
標題以應力波法非破壞檢測混凝土植筋epoxy握裹長度
作者鄧凱均、莊江隆、林宜清、江國睿
關鍵字植筋品質、非破壞檢測、應力波動、敲擊回音法
摘要本文開發以波動技術非破壞檢測植筋握裹長度與植筋深度。首先以有限元素法對植筋結構之應力波動訊號進行數值模擬分析，以瞭解植筋之波動行為，並經由植筋試體之敲擊回音試驗來驗證數值分析結果。研究結果顯示，在頻譜圖中可以發現明顯尖峰位於主導頻率上，該主導頻率主要由植筋外露長度與植筋握裹長度所控制，對特定之植筋外露長度時，植筋握裹長度越長所得頻率就越高。本文以數值分析建立三種不同植筋外露長度(10、15 與20公分)，頻率與植筋握裹長度間之關係曲線。試驗檢測結果與數值模擬相當吻合。研究結果建議現場植筋握裹長度檢測程序如下：(1)以超音波測得植筋總長度，由測得之植筋總長度扣除外露長度即可求得植筋深度；(2)執行敲擊回音試驗測得主導頻率，代入所建立的迴歸方程式，即可以預估植筋握裹長度。試驗結果顯示預估之植筋握裹長度誤差大都在1 公分以內，證明本文所開發檢測法可以作為現地植筋施工品質之檢驗用。
TitleUse of Stress Wave methods for Nondestructive Inspection of Epoxy-Bonded Length of Post-installed Rebars in Concrete
AuthorKai-Chung Teng, Chiang-Lung Chuang, Yiching Lin, Guo-Ruei Jiang
Keywordsquality of planting bars, nondestructive evaluation, stress waves, impact-echo
AbstractThis article develops a stress wave-based technology to detect non-destructively the epoxy-bonded length and embedded depth of post-installed rebars in concrete. Firstly, the finite element method (FEM) was used to simulate the stress wave propagation signal of the post-installed rebars in concrete to understand the wave propagation behavior of anchorage rebar. The results of the numerical analysis were verified by the impact-echo test performed on the concrete specimens containing post-installed rebars. The results show that a high amplitude peak can be found at the dominant frequency in the spectrum. The dominant frequency is mainly controlled by the exposed length and the epoxy-bonded length of the post-installed rebar. For a specific exposed length of the planting rebar, the longer the epoxy-bonded length, the higher the dominant frequency. In this paper, numerical analysis of three different exposed lengths (10,15 and 20 cm) were considered to establish the relationship between the dominant frequency and the epoxy-bonded length. The experimental results are in good agreement with those obtained from the numerical simulation. The results obtained from this study suggested that the epoxy-bonded length of post-installed rebar can be evaluated as follows: (1) The total length of the post-installed rebar can be measured by ultrasound. The embedded depth of the post-installed rebar is obtained by deducting the exposed length from the measured total length; (2) Impact-echo test measured the dominant frequency. The epoxy-bonded length can be predicted by substituting the dominant frequency into the established regression equation. The test results show that the estimated error of embedding length of post-installed rebar is mostly within 1 cm, which proves that the test method developed in this paper can be used to evaluate the quality of planting bars.
標題台灣混凝土變形預測模式B4-TW 建置(ㄧ)：基本潛變、乾燥潛變與總潛變
作者劉庭愷、陳振川
關鍵字混凝土、長期變形、潛變、收縮、資料庫
摘要台灣目前之混凝土工程設計規範缺乏混凝土潛變之預測公式，工程師設計大多依循美國ACI 規範，參考美國AASHTO 公路橋梁設計規範；歐洲CEB-FIP、RILEM；或日本JSCE、JCI 等作法。基於台灣混凝土材料、配比、施工與環境之地區特性，台灣著實需要發展良好之本土化混凝土潛變預測公式。本文指出運用現有之國內外混凝土潛變模式預測台灣混凝土資料之情形，結果顯示大多現有模式皆呈現低估的現象。本研究評估並選用Bažant 2015年提出之Model B4 潛變預測公式為基礎，針對上述之台灣混凝土特性進行本土化修正，分別是在瞬時應變項中考慮因粒料堅實度較為不足造成之混凝土彈性模數折減；在基本潛變項中考慮因高漿體量及粒料性質造成高變形之現象；在乾燥潛變項中考慮台灣常用之砂岩粒料造成之影響。結果顯示，進行本土化修正後之Model B4-TW 潛變預測公式與原始Model B4相比，預測台灣混凝土基本潛變資料時，迴歸分析中之決定係數 R2由 0.52提升至0.78；預測總潛變資料變形時R2由 0.76 提升至 0.81。除 R2外，各國學者提出之不同統計指標也顯示Model B4-TW 預測台灣潛變資料之表現較佳，建議發展成為適用台灣本土之混凝土潛變預測公式。
TitleEstablishment of B4-TW Prediction Model for Concrete Deformation in Taiwan ( I ) :Basic Creep, Drying Creep and Total Creep
AuthorTing-Kai Liu, Jenn-Chuan Chern
KeywordsConcrete, Long-term Deformation, Creep, Shrinkage, Database
AbstractAt present the concrete design code in Taiwan lacks any predictive model for concrete creep, which is why most engineers in Taiwan follow the models of the American Concrete Institute (ACI) or the American Association of State Highway and Transportation Officials (AASHTO) of the US; the European CEB-FIP and RILEM ; or the methods of the JSCE or JCI of Japan. Although the physical and chemical characteristics of concrete are essentially the same all across the world, each location uses its own constituent materials and mix design. In the present study, looking at the establishment of a concrete creep database for concrete in Taiwan, we have seen that the aggregate used in concrete of Taiwan is of lower quality. When formulating a mix design to attain higher strength, the resulting concrete will tend to have a high paste content, high cement content, low water cement ratio, and low aggregate/cement ratio. These local characteristics of concrete in Taiwan may lead to inaccuracies when they are applied to foreign predictive formulas, and in turn influence the structural behavior and safety of the concrete structures. Taiwan therefore has a manifest need for developing better localized predictive models for concrete creep. This study first presents the results from the predictive models for concrete creep (foreign and domestic formulas) applied to concrete in Taiwan. At present, it may be seen that the norms tend to undervalue. Then, it evaluates and actually uses the Model B4 predictive model for concrete creep suggested by Bažant in 2015 as a basis for the correction of characteristics in localized concrete in Taiwan in multiple situations: in instantaneous deformation items the reduction of the elasticity modulus in concrete due to low-quality aggregate was considered; in basic creep items the phenomenon of high levels of deformation due to high paste content and aggregate property were considered; in drying creep items the effect of sandstone aggregate, which is often used in Taiwan, was considered. Our results were as follows: after using the Model B4-TW model, which has been corrected for localized concrete in Taiwan, we may compare the two models (Model B4 and Model B4-TW); when predicting basic creep for Taiwan concrete, the coefficient of determination R2 rose from 0.52 to 0.78; when predicting the total strain, R2 rose from 0.76 to 0.81. In addition to R2, the statistical indicators given by scholars from around the world have shown that the predictive capabilities of the Model B4-TW model for concrete creep data in Taiwan are superior to other models; thus it can be further developed as a predictive model for concrete creep in Taiwan.
標題台灣混凝土變形預測模式B4-TW 建置(二)：乾縮、自體收縮與總收縮
作者秦維邑、陳振川
關鍵字混凝土、長期變形、收縮、高爐石粉、飛灰、資料庫
摘要目前台灣之混凝土工程設計規範之混凝土收縮計算並未有明確公式，未能和混凝土材料之性質連結。致其計算常使用國外之美國 ACI、AASHTO，歐洲 CEB-FIP、RILEM 等預測公式。混凝土變形問題仍因牽涉世界各地區氣候環境、組成材料、配比及施工實務等，而有所差異性。台灣混凝土使用之粒料性質堅實度較為不足，配比設計時為追求強度達標，有使用高漿體量、高水泥量、低水灰比、低粒料量⁄水泥量比等特性，上述之本土化特性非使用國外預測公式可掌握，故台灣著實需要發展良好之本土化混凝土收縮預測公式。經評估現有國內外混凝土收縮預測規範，本文選用美國西北大學Bažant等人發展於2015 年提出之Model B4 收縮預測公式為基礎。針對上述之台灣混凝土特性進行本土化的修正，並考慮台灣常用之砂岩粒料造成之影響，找出適用於台灣之粒料修正參數。本文亦針對含有礦物摻料之混凝土進行摻料 影響之修正，選用FIB2000 作為自體收縮時間成長曲線，並修正Model B4 之礦物摻料參數表格，建立適合台灣使用之內含自體收縮項目的Model B4-TW 收縮預測公式。結果顯示，進行本土化修正後之Model B4-TW 收縮預測公式，在預測台灣普通混凝土或含有礦物摻料混凝土收縮時，均有極優表現，可發展為適用台灣本土之混凝土收縮預測公式。
TitleEstablishment of B4-TW Prediction Model for Concrete Deformation in Taiwan ( II ) : Drying Shrinkage, Autogenous Shrinkage and Total Shrinkage
AuthorWei-Yi Chin, Jenn-Chuan Chern
Keywordsconcrete, long-term deformation, shrinkage, blast-furnace slag cement, fly ash, dataset
AbstractAt present, there is no definite formula for concrete shrinkage calculation in the concrete engineering design code of Taiwan, which cannot link with the nature of local concrete material. Most engineers in Taiwan often use the formula of American Concrete Institution (ACI), the American Association of State Highway and Transportation Officials (AASHTO), and European CEB-FIP and RILEM codes. The problem of concrete deformation is still different because it involves the climate environment, mix design, proportion and construction practice in different areas. The aggregate quality of the concrete used in Taiwan is poor, and the mix is designed to achieve the strength with the use of high paste volume, high cement content, low water/cement ratio, low aggregate/cement ratio and other characteristics. The localization characteristics described above cannot be mastered by foreign prediction formula, so Taiwan really needs to develop a good local concrete shrinkage prediction formula. Based on the evaluation of the existing domestic and foreign concrete shrinkage prediction formulae, this paper chooses the model B4 shrinkage prediction formula developed in 2015 by Bažant of Northwestern University. With regard to the local characteristics of the concrete in Taiwan, and the effect of the commonly used sandstone aggregate in Taiwan, the modified parameters of the aggregate are found. In this paper, the influence of concrete containing mineral admixture is modified: the FIB2000 is selected as autogenous shrinkage time growth curve; and the mineral admixture parameter table of model B4 is modified. These local modifications led to the establishment of the Model B4-TW. The results show that the model B4-TW shrinkage prediction formula, which included autogenous shrinkage, after localization correction has excellent performance in predicting the shrinkage of normal concrete or concrete containing mineral admixture in Taiwan, and can be developed as a concrete shrinkage prediction formula for Taiwan.
標題鋼筋混凝土構架填充低台度磚牆之試驗研究
作者張順益、吳秉祈、巫垂晃
關鍵字鋼筋混凝土、低台度磚牆、反覆載重試驗、側推分析，剪力強度
摘要國內老舊校舍建築物在受到地震侵襲時，常因鋼筋混凝土構架內填充台度磚牆而發生短柱破壞。其中台度磚牆所提供的側向剪力強度，即是評估是否發生短柱破壞的重要因子，而台度磚牆的側向抗剪強度可能因其高寬比以及臨界破壞角的不同而有所差異。由於現行估算方法並未考慮台度磚牆高寬比的影響，因此並無法真實反應台度磚牆的側向剪力強度。本文特別針對低台度磚牆的側向抗剪強度進行三座試體的試驗研究，其中一座為空構架試體以及兩座填充不同高度之低台度磚牆構架試體，用來做為推估鋼筋混凝土構架內低台度磚牆側向剪力強度的重要依據。此三座試體除了進行反覆載重試驗之外，也利用側推模擬分析探討其耐震行為，將分析結果與試驗結果進行比較以推估低台度磚牆的側向剪力強度。從試驗結果可以得知低台度磚牆的高寬比為其側向剪力強度的重要因子之一，因此在推估低台度磚牆的側向剪力強度時，若能將高寬比這項因子適度的反應在計算的公式中，將可以更真實的預測台度磚牆的側向剪力強度。本研究已據此原則研擬出鋼筋混凝土構架填充低台度磚牆的剪力強度計算公式。
TitleExperimental Study of Reinforced Concrete Frame Filled with Low Masonry Window Spandrel
AuthorShuenn-Yih Chang, Ping-Chi Wu, Tsui-Huang Wu
KeywordsReinforced Concrete Building, Low Masonry Window Spandrel, Seismic Evaluation, Pushover Analysis
AbstractIn Taiwan area, structural damages caused by short column effect are very common in school buildings. The short column failure is closely related to the shear strength of the masonry window spandrel infilled within a reinforced concrete frame. The shear strength of a masonry window spandrel might be highly affected by its height-width ratio. However, this factor is not considered in the current evaluating formula and thus this formula seems unable to faithfully predict the shear strength. In fact, a formula for estimating the shear strength of a masonry window spandrel has been proposed. Because the height-width ratio of the masonry window spandrel was not considered in the formula its application is limited or might be inappropriate. To improve thisformula, three reinforced concrete frames were designed and fabricated for the cyclic loading tests for predicting the shear strength of a low masonry window spandrel within a reinforced concrete frame. One is a pure frame and the other two frames were infilled with different height of the masonry window spandrels. After conducting the cyclic loading tests of the three frames, the pushover analysis of each frame was also performed. Hence, after comparing the analytical result with the experimental results, the shear strength of the masonry window spandrel can be estimated. In this work, the height-weight ratio is chosen as an important factor for the newly proposed formula to estimate the shear strength of a low masonry window spandrel within a reinforced concrete frame. As a result, an improved formula for predicting the shear strength of the low masonry window spandrel within a reinforced concrete frame is proposed in this work.