輕質粒料混凝土全尺寸柱之承載行為

load bearing behavior of full-size lightweight aggregate concrete column

陳威丞(wei-cheng chen)

指導教授 ： 顏聰 ； 干裕成

朝陽科技大學/理工學院/營建工程系/碩士(2010年)

摘要

本文以水庫淤泥燒製之輕質粒料，製作全尺寸輕質粒料混凝土RC構件之承重行為與尺寸效應，進行無偏心之載重試驗。試體斷面採用方形柱，邊長分24cm，36cm及48cm三種，柱之細長比統一取21.6，各式斷面對應的柱試體長度分別為150cm、225cm及300cm。製作柱試體之混凝土強度包括245 kgf/cm2及350 kgf/cm2兩種。各組柱之補強鋼筋均依ACI規範之最小鋼筋比設計。
試驗結果顯示，輕質混凝土柱的破壞過程近似於常重混凝土柱者，柱體破壞都是在中間部位產生剪斜裂縫。承受相同載重下，輕質混凝土柱會產生較大變位。中、小型輕質混凝土柱的極限載重試驗值(Pu,t)與ACI標稱強度計算值(Pn,max)相近，表示ACI建議的標稱強度可適用於中、小型輕質混凝土柱的設計。輕質混凝土柱的Pu,t/ Pn,max值皆隨柱尺寸之增加而減小；混凝土強度越高，其Pu,t/ Pn,max值也愈低。這些現象都顯示輕質混凝土柱具有尺寸效應，在設計上應考慮該尺寸效應。

關鍵字

混凝土 ； 柱 ； 軸向載重

並列摘要

In this research the full size lightweight aggregate concrete columns, made with sedimentary lightweight aggregate were cast to investigate the behavior of axial loading capacity and the size effect. Three sections of square column specimen adopted in this experiment are 24x24cm, 36x36cm and 48x48cm. The slenderness ratio of all columns is taken as 21.6, and the corresponding heights of specimens are 150cm, 225cm, and 300cm, respectively. Two concrete compressive strength of 245 kgf/cm2 and 350 kgf/cm2 were selected. Each column was arranged with minimum reinforcements according to ACI code.
Test result indicates that the failure mode of lightweight concrete column is similar to that of normal weight concrete column. Both of them failed by occurring inclined shear cracks appear at the middle part of column specimen. Under the same axial loading, lightweight concrete column demonstrates larger displacement. The measured ultimate strengths(Pu,t) of lightweight concrete column of medium (36x36cm) and small (24x24cm) size are similar to that of ACI nominal strength (Pn,max). This means that the nominal strength suggested by ACI can be applied on the strength prediction of medium and small size lightweight concrete column. In addition, it was also found that the Pu,t/Pn,max value of lightweight concrete column decreases with the increase of column size, and the higher the strength of concrete, the lower the Pu,t/Pn,max value. This results indicate that the lightweight concrete column has the incentive of size effect. Therefore, the size effect should be considered in the design of lightweight concrete column.

並列關鍵字

concrete ； column ； load bearing

參考文獻

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