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（福州大學(xué)土木工程學(xué)院，福州 350002）
［摘要］進(jìn)行了從某公路橋拆下的兩根空心板梁現(xiàn)場足尺試驗(yàn)，采用裂縫寬度測試儀、應(yīng)變片和導(dǎo)桿引伸儀三種方法來確定消壓荷載，采用簡化彈性方法計(jì)算現(xiàn)存預(yù)應(yīng)力，以受壓區(qū)混凝土破壞為破壞準(zhǔn)則來確定極限荷載。采用應(yīng)變片方法來確定消壓荷載最具有重復(fù)性和可靠性，采用裂縫寬度測試儀方法來確定消壓荷載偏于不安全；按現(xiàn)行公路橋規(guī)（JTG D62—2004）中確定預(yù)應(yīng)力損失的方法計(jì)算預(yù)應(yīng)力筋相應(yīng)的各種損失，對(duì)試件的開裂荷載、消壓荷載、現(xiàn)存預(yù)應(yīng)力和極限荷載進(jìn)行理論計(jì)算；實(shí)測結(jié)果與理論計(jì)算結(jié)果基本吻合，可為既有預(yù)應(yīng)力混凝土梁現(xiàn)存預(yù)應(yīng)力和極限荷載的確定提供參考。
［關(guān)鍵詞］現(xiàn)存預(yù)應(yīng)力；開裂荷載；消壓荷載；極限荷載
Evaluation of effective prestress force and ultimate load in prestressed concrete beams
Chen Yong，F(xiàn)ang Zhenzheng(Engineering Education in Fuzhou University, Fuzhou 350002，China)
Abstract:The results of an experimental study to determine the effective prestress force in two full-scale prestressed void floor-beams are presented. Three methods are used to determine the decompression load: 1) visual observation of crack opening, 2) strain gauges, 3) displacement transducers. The effective prestress force is calculated by the simple elastic method through the decompression load near the cracks. The ultimate load is determined through the failure occurred by crushing of the concrete in the compression zone. The result of the experiment presents that the decompression loads obtained from the strain gauges are found to be repeatable and reliable in the three methods. It also presents that it is not safe to determine the decompression load by visual observation of crack opening. Based on the -Code for design of highway reinforced concrete and prestressed concrete bridges and culverts(JTG D62—2004)of China, the prestress loss of bars is calculated. The effective prestress force, cracking load, decompression load and ultimate load are calculated. The calculation results agree well with the measured results. It provides the reference to evaluate the effective prestress force and ultimate load in the prestressed concrete beams.
Keywords:effective prestress force; cracking load; decompression load; ultimate load
作者簡介：
陳勇，博士研究生。Email: cy_9923@126.com。
參考文獻(xiàn)
［1］STEPHEN PESSIKI, MARK KACZINSKI，HERBERT H  WESCOTT. Evaluation of effective prestress force in 28-year-old prestressed concrete bridge beams［J］. PCI Journal, 1996, 41(6).
［2］房貞政. 預(yù)應(yīng)力結(jié)構(gòu)理論與應(yīng)用［M］. 北京：中國建筑工業(yè)出版社，2005.