本文關(guān)鍵詞：體外預(yù)應(yīng)力梁的摩擦效應(yīng)和二階動力分析　出處：《華僑大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 摩擦效應(yīng)體外預(yù)應(yīng)力連續(xù)梁 動力分析壓縮軟化效應(yīng)

【摘要】：體外預(yù)應(yīng)力技術(shù),作為后張預(yù)應(yīng)力體系的重要部分,憑借施工簡單、體外筋便于修理、替代等優(yōu)點,在建筑以及橋梁領(lǐng)域得到快速發(fā)展,近年來更是在新建結(jié)構(gòu)以及既有結(jié)構(gòu)加固中得到廣泛應(yīng)用。目前,關(guān)于體外預(yù)應(yīng)力結(jié)構(gòu)的研究主要集中于簡支梁以及靜力性能方面,而對于連續(xù)梁和動力特性的研究相對偏少,尤其是關(guān)于體外筋與轉(zhuǎn)向座之間的摩擦效應(yīng)方面更有待深入研究。本文主要進行體外預(yù)應(yīng)力梁摩擦效應(yīng)以及二階動力分析�；仡欝w外預(yù)應(yīng)力增量的計算方法,并對各類計算方法的使用范圍以及特點進行對比分析。引入簡明的摩擦單元模擬轉(zhuǎn)向座與體外筋間的摩擦效應(yīng),該單元位于轉(zhuǎn)向座與相鄰兩段體外筋的角平分線上。進行各種因素下簡支梁和連續(xù)梁的計算,包括不同的摩擦系數(shù)、體外筋面積、偏心距、荷載作用以及對稱與反對稱的加載模式。計算結(jié)果表明:偏心距對體外預(yù)應(yīng)力增量影響明顯;摩擦可降低梁的撓度和最大彎矩值,增加預(yù)應(yīng)力增量;對于簡支梁以及受對稱荷載的連續(xù)梁,可以忽略彎矩、撓度的摩擦效應(yīng),但是對預(yù)應(yīng)力增量的影響明顯,對于受非對稱荷載的連續(xù)梁,彎矩、撓度的摩擦效應(yīng)不能忽略,對預(yù)應(yīng)力增量的影響更為明顯。本文分別采用等效剛度法、能量法以及集中質(zhì)量法對體外預(yù)應(yīng)力梁自振頻率進行求解。在等效剛度法中,考慮體外筋對剛度的貢獻,將體外預(yù)應(yīng)力連續(xù)梁轉(zhuǎn)化為具有更大剛度的受壓梁。已有研究表明,無粘結(jié)與有粘結(jié)混凝土梁的預(yù)壓力沒有壓縮軟化效應(yīng),但是在體外預(yù)應(yīng)力中預(yù)壓力是否有壓縮軟化效應(yīng),未見相關(guān)文獻研究。故在能量法中,本文著重研究體外預(yù)壓力對梁二階效應(yīng)的影響,提出壓縮軟化效應(yīng)的概念,得出預(yù)壓力影響系數(shù)跟轉(zhuǎn)向座數(shù)目有關(guān)。隨著接觸點數(shù)目的增加,偏心距損失減小,體外筋趨向于無粘結(jié)筋,預(yù)壓力影響系數(shù)降低至趨于0,體外預(yù)壓力幾乎不產(chǎn)生壓縮軟化效應(yīng),幾乎不影響梁的自振頻率。在集中質(zhì)量法中,在梁單元的彎曲剛度矩陣中引入預(yù)應(yīng)力影響系數(shù),考慮預(yù)壓力對梁的影響。將三種方法的計算結(jié)果進行對比分析,得出考慮預(yù)壓力影響下的能量法結(jié)果更為精確。
[Abstract]:External prestressing technology, as an important part of post-tensioned prestressing system, has been developed rapidly in the field of buildings and bridges by virtue of its simple construction, easy repair and replacement of external tendons. In recent years, it has been widely used in the construction and reinforcement of existing structures. At present, the research on externally prestressed structures is mainly focused on simply supported beams and static behavior. However, the study of continuous beam and dynamic characteristics is relatively less. Especially the friction effect between the external tendons and the steering seat needs to be further studied. The friction effect of the externally prestressed beam and the second-order dynamic analysis are mainly carried out in this paper. The calculation method of the external prestressing increment is reviewed. The application range and characteristics of various calculation methods are compared and analyzed. A concise friction element is introduced to simulate the friction effect between steering seat and external tendons. The element is located on the angular bisection line between steering seat and adjacent segments of external tendons. The calculation of simply supported beam and continuous beam under various factors, including different friction coefficient, external reinforcement area, eccentricity. The results show that the eccentricity has an obvious effect on the external prestressing increment. Friction can reduce the deflection and maximum bending moment of the beam and increase the prestress increment. For simply supported beams and continuous beams subjected to symmetric loads, the friction effects of bending moment and deflection can be ignored, but the effect on prestress increment is obvious, and for continuous beams subjected to asymmetric load, bending moment can be neglected. The friction effect of deflection can not be ignored, and the effect on prestress increment is more obvious. The equivalent stiffness method is adopted in this paper. In the equivalent stiffness method, the contribution of external tendons to stiffness is considered. The external prestressing continuous beam is transformed into a compression beam with greater stiffness. It has been shown that there is no compression softening effect in the pre-pressure of unbonded and bonded concrete beams. However, there is no literature study on whether pre-pressure has compression softening effect in external prestress, so in the energy method, this paper focuses on the effect of external pre-pressure on the second-order effect of beam. The concept of compression softening effect is put forward and the influence coefficient of pre-pressure is related to the number of steering seat. With the increase of the number of contact points the loss of eccentricity decreases and the external tendons tend to be unbonded tendons. When the influence coefficient of pre-pressure is reduced to 0, there is almost no compression softening effect and almost no effect on the natural vibration frequency of the beam in the concentrated mass method. The influence coefficient of prestress is introduced into the bending stiffness matrix of beam element, and the influence of pre-pressure on beam is considered. The results of the three methods are compared and analyzed. It is concluded that the energy method is more accurate considering the influence of prepressure.
【學(xué)位授予單位】：華僑大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：O342

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