使用階段混凝土的主應(yīng)力驗(yàn)算

(1)使用階段混凝土的主應(yīng)力驗(yàn)算為保證主梁具有足夠的抗剪強(qiáng)度，需要驗(yàn)算各控制截面的主拉應(yīng)力和主壓應(yīng)力，混凝土主拉應(yīng)力和主壓應(yīng)力。混凝土主拉應(yīng)力和主壓應(yīng)力按《公路橋涵設(shè)計(jì)規(guī)范》預(yù)規(guī)第5.2.17條計(jì)算：1o=o/2—[(o/2)2+t2]2o=o=o/2+[(o /2)2+t2]2zahxhx如圖所示截面各節(jié)線以上部分對(duì)中性軸的靜矩見(jiàn)下表-中性軸-中性軸截面號(hào)1-12-23-3中性軸3016.270135.414935.348031.2422554.26094.69944.13314.5824計(jì)算結(jié)果見(jiàn)下表：一截面項(xiàng)目對(duì)m的計(jì)算max30551-1正應(yīng)力o=N/A+MY/I6.263.93剪應(yīng)力t=QS/BI-0.400.03王拉應(yīng)力o=o/2—[(o/2)2+t2)]1/2zl-0.030王壓應(yīng)力o =o/2+[(o/2)2+t2)]1/2zl6.293.932-2正應(yīng)力o=N/A+MY/I6.302.93

剪應(yīng)力t=QS/BI-0.40-0.03王拉應(yīng)力o=o/2一[(o/2)2+t2)]1/2zl-0.030王壓應(yīng)力o =o/2+[(o/2)2+t2)]1/2zl6.332.933-3正應(yīng)力o=N/A+MY/I6.242.59剪應(yīng)力t=QS/BI-0.38-0.02王拉應(yīng)力o=o/2一[(o/2)2+t2)]1/2zl-0.020王壓應(yīng)力o =o/2+[(o/2)2+t2)]1/2zl6.262.59中性軸處正應(yīng)力o=N/A+MY/I6.002.71剪應(yīng)力t=QS/BI-0.48-0.03主拉應(yīng)力o=o/2-[(o/2)2+t2)]1/2zl-0.040主壓應(yīng)力o =o/2+[(o/2)2+t2)]1/2zl6.042.71截面項(xiàng)目對(duì)m的計(jì)算min30551-1正應(yīng)力o=N/A+MY/I4.133.35剪應(yīng)力t=QS/BI-0.480.003王拉應(yīng)力o=o/2一[(o/2)2+t2)]1/2zl-0.060王壓應(yīng)力o =o/2+[(o/2)2+t2)]1/2zl4.193.352-2正應(yīng)力o=N/A+MY/I4.30-0.07剪應(yīng)力t=QS/BI-0.480.003王拉應(yīng)力o=o/2一[(o/2)2+t2)]1/2zl-0.050王壓應(yīng)力o =o/2+[(o/2)2+t2)]1/2zl4.35-0.073-3正應(yīng)力o=N/A+MY/I4.06-1.24剪應(yīng)力t=QS/BI-0.460.03

王拉應(yīng)力b=b/2一[(b/2)2+12)]1/2zl-0.050王壓應(yīng)力b =b/2+[(b/2)2+12)]1/2zl4.11-1.24中性軸處正應(yīng)力b=N/A+MY/I3.10-0.84剪應(yīng)力i=QS/BI-0.57-0.003王拉應(yīng)力b=b/2一[(b/2)2+12)]1/2zl-0.100王壓應(yīng)力b =b/2+[(b/2)2+12)]1/2zl3.20-0.84從表中的計(jì)算結(jié)果看所有主拉應(yīng)力均滿足《公路橋涵設(shè)計(jì)規(guī)范》預(yù)規(guī)第5.2.24