【摘要】：溫度作用是公路橋梁設計中需考慮的主要荷載之一,它的分布形式及大小直接關系到橋梁結構的安全性、適用性和耐久性。我國現(xiàn)行的《公路橋涵設計通用規(guī)范》JTJD60-2004直接沿用了美國AASHTO規(guī)范中關于溫度作用計算的規(guī)定,未考慮我國地域差異及混凝土鋪裝層厚度對豎向溫度梯度分布及最大溫差的影響。為此,本文結合橋梁通用規(guī)范修訂項目“公路橋梁豎向梯度模型研究”,開展了混凝土T型公路橋梁溫度場的觀測及溫度應力分析。本文主要內(nèi)容和結論如下： (1)針對溫度作用,歸納總結了國內(nèi)外規(guī)范的差異。 (2)制作了50mm、100mm兩種不同厚度瀝青混凝土和150mm、200mm兩種不同厚度素混凝土鋪裝的混凝土T型梁,從2013年4月起至2014年2月,對8個橫斷面146個測點的溫度進行了連續(xù)監(jiān)測。結果發(fā)現(xiàn),混凝土T型梁橫向、縱向溫差不大,豎向溫差較大,兩種鋪裝層T型梁截面豎向溫差分別約為14℃和5℃。與公路橋涵規(guī)范相比,本試驗瀝青混凝土鋪裝層T型梁的最大溫差均低于規(guī)定值(分別為20℃和14℃),混凝土鋪裝層也大大降低了橋梁最大溫差值。規(guī)范溫度梯度模式采用雙折線,本試驗瀝青鋪裝層試件采用對數(shù)函數(shù)和雙折線分布函數(shù)表示,雙折線函數(shù)的轉折點在距離橋面板頂面O.1m的位置處�；炷龄佈b層試件采用指數(shù)函數(shù)和三折線函數(shù)描述,三折線函數(shù)的轉折點分別在距離橋面板頂面0.25m和0.6m的位置處。對每一個單位(10天)的最大溫差進行統(tǒng)計,發(fā)現(xiàn)全年的日最大溫差隨時間呈正弦函數(shù)變化。 (3)結合溫度場有限元理論,利用實測資料及氣象資料確定了綜合溫度、熱交換系數(shù)等參數(shù)及混凝土的熱物理性能參數(shù),采用ANSYS有限元軟件對混凝土T型梁進行了瞬態(tài)溫度場的仿真模擬,并與實測值進行了對比。結果表明,溫度場的理論計算值與實測值較為接近,且沿豎向走勢也基本一致,這說明輸入的參數(shù)值基本準確。 (4)采用理論公式和有限元軟件MIDAS/Civil分別對七種溫度梯度模式下的橋梁溫度應力進行了計算。結果表明,不同溫度梯度模式下橋梁沿梁高的溫度應力趨勢基本相同,即,梁頂板受壓,腹板受拉,梁底受壓。翼緣下方0.1m范圍內(nèi)的拉應力偏大,是裂縫產(chǎn)生潛在區(qū)域,在工程設計時應該加以注意。
[Abstract]:The effect of temperature is one of the main loads to be considered in the design of highway bridges. Its distribution and size are directly related to the safety, applicability and durability of bridge structures. The current General Code for Design of Highway Bridges and culverts in China JTJD60-2004 directly follows the provisions of the AASHTO Code of the United States on the calculation of temperature effects without considering the influence of regional differences in China and the thickness of concrete pavement on the vertical temperature gradient distribution and maximum temperature difference. In this paper, the temperature field observation and thermal stress analysis of concrete T-type highway bridge are carried out in combination with the project of "study on Vertical gradient Model of Highway Bridge", which is the revision project of general specification for bridges. The main contents and conclusions of this paper are as follows: (1) aiming at the effect of temperature, The differences of specifications at home and abroad are summarized. (2) two kinds of concrete T-beams with different thickness of 50mm / 100mm asphalt concrete and 150mm / 200mm plain concrete with different thickness are made, from April 2013 to February 2014, The temperature of 146 measuring points on 8 cross sections was continuously monitored. The results show that the transverse, longitudinal and vertical temperature difference of T-beam is small, and the vertical temperature difference is about 14 鈩，

本文編號：2207662