不同跨度之T形梁在反覆荷載下有效版寬的研究

The Influence of the Shear Span on the Effective Width under Cyclic Loading of T-Beams

柯舜文(Shun-wen Ko)

指導教授 ： 王勇智

國立中央大學/工學院/土木工程學系/碩士(2013年)

摘要

現今對於有翼版梁的設計案例中，大都以空構架來進行分析，工程師為了簡化設計，往往會忽略有效版寬內版筋的貢獻而低估梁在受負彎矩下的彎矩容量。在鄭智仁2012年的研究[8]發現，長跨度梁與短跨度梁在反覆荷載下的有效版寬有顯著差異。有效版寬內之版筋降伏時機亦會隨著版筋與梁腹的距離和層間變位角的關係而改變，如何計算有效版寬內版筋受拉時所貢獻的彎矩強度為本文探討的重點。
實驗結果顯示，獨立T形梁在初始受力階段，長梁(a/d>2.5)負向初始勁度，均高出正向初始勁度10%，版參與的貢獻較短梁(a/d<2.5)顯著，梁的跨度可能為影響版參與初始勁度比例的因素之一。
短跨度T形梁(a/d=2.44)受負彎矩下的有效版寬，一次澆置試體為1.4Ln，二次澆置的試體為2Ln，長跨度T形梁(a/d=3.33與a/d=5.51)的有效版寬則為試體全版寬，故T形梁的跨度確實是影響有效版寬的因素之一，以現今規範ACI 318-11正彎矩對獨立T形梁有效版寬規定(4bw)，作為負彎矩之有效版寬明顯不保守。

關鍵字

T形梁 ； 有效版寬 ； 耐震行為

並列摘要

The purpose of the experimental study is to investigate the relationship between effective width and the shear span under cyclic loading. When referring to slab participation in practical design, engineers usually ignored the effective width in negative moment.
According to the research [8] in 2012, the effective widths are different between short beams and slender beams. Furthermore, the slab participation is a drift-controlled problem, the effective width would increase with the drift ratio. To estimate the contribution of slab reinforcements in negative moment is the most important thing.
The test results indicate the initial stiffness of slender beams (a/d>2.5) in negative moment were higher than positive moment about 10%, and it was found that the slab participation in initial stiffness of slender beams were more obvious than the short beams (a/d<2.5). Probably, the shear span is one of the factors in slab participation in initial stiffness.
The effective width of short beams (a/d<2.5) with construction joint were wider than the beam without construction joint, and the effective width of slender beams were all full of the width. According to the effective width design of ACI 318-11 (4bw), it may not be conservative in negative moment.

並列關鍵字

T-Beams ； Shear Span ； Effective Width ； Cyclic Loading

參考文獻

[8] 鄭智仁， 「預鑄施工梁與版間冷縫對T形斷面梁耐震行為之影響」，國立中央大學，碩士論文，民國一百零一年。

[10] 許禎祐，「有鋼筋截斷之RC梁耐震行為探討」，國立中央大學，

[12] 陸景文、詹穎雯、陳振川，「台灣地區混凝土抗壓強度與彈性模數特性研究」，中國土木水利工程學會學刊，第十四卷，第三期，第371-379頁，民國九十三年。

[2] ACI-ASCE Committee 352, “Recommendations for Design of Beam-Column Joints in Monolithic Reinforced Concrete Structures ,” American Concrete Institute, 2002, pp.3-5.

Earthquake Design of Reinforced Concrete Frames,” ACI Structural Journal, July-Aug., 2002.