SRC構材之力學行為與偏心距法在梁柱設計之應用

Abstract

本研究首先探討SRC構材中鋼骨與混凝土介面合成作用之力學行為，並應用一般RC柱設計所採用偏心距法之概念，提出一套新的SRC梁柱強度設計法。 關於SRC梁斷面中鋼骨與混凝土之間合成作用的考量，日本AIJ-SRC規範(1987)假設合成作用可以忽略，而美國ACI-318規範(1995)則假設為完全合成。因此為釐清此一問題，本研究蒐集了相關的SRC構材實驗資料，經由詳細觀察SRC梁斷面中之應變分佈情形，以深入瞭解鋼骨與混凝土間合成作用之真實情況。再進一步考量合成作用對SRC梁彎矩強度之影響，進而推導出一組可以預測部份合成梁極限彎矩強度的理論公式。 此外，本研究結合美國AISC-LRFD鋼結構設計規範(1993)與ACI結構混凝土設計規範(1995)，以「偏心距法」與「強度疊加」的概念發展出一套簡單、快速的SRC梁柱強度設計法。本研究於過程中並應用美國加州大學柏克萊分校所發展之電腦分析程式BIAX，來模擬SRC構材中鋼骨、鋼筋與混凝土材料之非線性特性。最後，本研究並蒐集國內外SRC梁柱之實驗資料，來比較本研究建議法與各國規範對SRC梁柱構材強度之預測結果。

The objectives of this research are to investigate the composite action between the steel and the RC parts of SRC structural members and to develop a new method for predicting the ultimate strength of concrete encased SRC beam-columns. The AIJ-SRC (1987) code calculates the beam flexural capacity by superposition method which neglects the composite action between the steel shape and the RC portion. But the ACI-318 code (1995) takes the SRC section as fully composite. In order to understand the actual behavior of SRC beams, some test results was collected to observe the strain distribution of SRC section. Then this research conducts an analytical study to determine the flexural capacity of a partially composite beam. Besides, this study extends the design concept used in ACI code for eccentrically loaded RC columns to the design of SRC beam-columns. Based on the concept of Strength Superposition, the component materials strength are determined by using the AISC-LRFD specification (1993) and the ACI code. This research also uses a computer program BIAX developed by University of California at Berkeley to model the nonlinear material behavior of the steel and the concrete. Finally, the predicted values are compared with previous test results and the proposed design codes.