貼片補強構件之層間應力分析; Interlaminar Stress Analysis of Patch Repaired Structural Components

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Title:	貼片補強構件之層間應力分析;Interlaminar Stress Analysis of Patch Repaired Structural Components
Authors:	黃偉智;Wei-Chi Hwang
Contributors:	土木工程研究所
Keywords:	層間應力;脫層;界面強度;非線性;錯開式;nonlinear;interlaminar stress;patch;FRP;concentration;debonding;concrete;staggered
Date:	2002-05-16
Issue Date:	2009-09-18 17:05:36 (UTC+8)
Publisher:	國立中央大學圖書館
Abstract:	摘要本論文探討貼片補強構件之層間應力分布，整體論文包含三部份。第一部份採用複利葉級數分析法構建混凝土構件貼片補強黏結強度測試系統中之層間應力分析模型。探討應力集中現象和貼片黏貼度、膠層厚度以及貼片、膠層和混凝土材料性質之間的關係，並配合國內外一系列的實驗數據，探討極限狀態下貼片、膠層、補強構件間之層間應力分布情形。透過解析解和實驗數據的反算之後，發現貼片、膠層、補強構件間之真正層間應力黏結強度和混凝土材料之抗拉強度之間趨近於一個固定比值，當貼片長度適當時其值固定而不隨貼片搭接長度之不同而改變，此一研究提出一貼片黏接強度實驗的解析模型，工程人員可依據本論文之反算方式，估算出一合理之黏結強度值，從而更能掌握正確的破壞荷載發生時刻，使得結構補強之極限荷載可作更精確的評估。第二部份以解析法探討鋼筋混凝土梁以FRP修補後之貼片和混凝土結構承受彎曲荷載下之層間應力問題；分析模型中將鋼筋及混凝土材料之非線性性質亦納入考慮，可較完整的探討貼片補強之RC梁發生破壞時整體結構之應力分布，研究發現鋼筋降伏及自由端效應，會造成FRP貼片在局部位置的層間剪應力之集中現象。此一解析所得之層間應力分佈現象，可用以解釋釵h實驗所觀察到的FRP剝離或脫層現象。第三部份探討以錯開式的貼片補強方式，由文中所推導之錯開式貼片補強RC梁之層間應力解析解可合理的求得以錯開式的貼片補強時，所產生之層間應力集中的位置及大小。於所推導出之結果發現不僅尾端處會出現應力集中，除此之外於錯開斷面之不連續處也會出現層間應力集中，而由後續的研究中更發現此應力集中之大小也可能產生界面脫層的發生。本文中所推導出之解析式為前人的研究中所無法得到之結果，藉由本文中所推導出之多層錯開式貼片補強RC梁之層間應力解析式於代入適當之邊界條件後，可作為往後進行多層漸錯式貼片補強之層間應力分析之基礎，可使未來進行工程設計時視需要而進行更精密可靠之斷面設計；另外於文中並藉由變化膠層厚度、貼片厚度、貼片楊式模數等方式進行參數研究。可由各種不同之複合模式以研究何者能更為降低界面之層間應力，以提高貼片補強構件之承載力。 Abstract In this thesis a series of analytical solutions of the interlaminar stresses of various types of patch repaired structural components are derived by Fourier analysis method. These analytical solutions can demonstrate how the stress concentration developed under various combinations of patch arrangement, loading condition and material properties and can reasonably explain the failure mechanisms of patched members observed in experiments. In the first part of this thesis, stress distributions among interfaces of a typical joint used for evaluating the shear strength of bond between patch plate and substrate are derived. This prediction model was further applied to back calculate the true bonding strength between FRP and concrete. It is found that the true bonding strength is many times higher than the one obtained by averaging the ultimate load with bonding area. From this true bonding strength value, a more precise loading capacity can be predicted for the retrofitting design of RC beam using FRP sheet. Bending analysis of reinforced concrete (RC) beams patched with steel or fiber reinforced plastic (FRP) plate is presented in the second part of this thesis. The non-linear stress-strain relationships of concrete and steel reinforcement are considered in the analysis model. The variation and distribution of the interfacial normal and shear stresses between the patching plate and RC beam for various combinations of load levels, plate thickness, material type, adhesive thickness and plate length are evaluated. It is found that the yielding of the steel reinforcements inside the concrete beam causes a discontinuous distribution of shear stress at the FRP-concrete interface. This discontinuous distribution of interfacial shear stress together with the stress concentration effect around the ends of the patched plate are applied to explain the debonding and peeling off failure mechanisms typically observed in the tests. It suggests that the proposed analytical model can be applied to estimate the ultimate load carrying capacity of the patch retrofitted RC beam for structural engineers. In the third part of this thesis, analytical model for the interfacial stress distributions of n layers staggering patched on RC beam is derived. Variations and distributions of the interfacial normal and shear stresses among patch plates and RC beam for various combinations of plate thickness, material type, adhesive thickness are investigated in detail.
Appears in Collections:	[Graduate Institute of Civil Engineering] Electronic Thesis & Dissertation

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