型鋼慣性矩的計算主要有兩種方法: 1、精確計算:增強型鋼的截面慣性矩可通過計算機計算,使用autocad軟件可對任意形狀的截面進行計算,所得結果非常精確,在這裡不再詳述。 2、對於簡單的截面,可用下面公式進行粗略的計算: ix=(bh3-bh3)/12(10) 公式中的數值見圖3-2:
下表列出實德主要型材增強型鋼的慣性距(此表僅作參考)實德主要型材增強型鋼慣性矩表iy (cm4)3.0mm2.17071.09080.88120.97133.79483.40852.10742.460211.28643.98910.98911.23021.09463.98911.3287 2.5mm1.90730.98170.79530.87482.68663.03011.86922.10399.55963.87760.87761.08700.96853.87761.1980 2.0mm1.60860.84850.68320.75822.12412.53801.58831.72027.80403.02170.76880.91890.82043.02171.0060 1.5mm1.26880.68690.56040.61481.66571.99691.26911.33135.96872.27140.61490.73240.65532.38590.7937 1.2mm1.04370.57480.46980.51501.36781.64091.05191.08154.82201.96600.50970.60590.54281.96600.6579 ix (cm4)3.0mm1.27433.51811.92682.53532.91123.46962.83023.31408.36751.15320.15320.19850.21721.15320.2475 2.5mm1.12523.09401.71102.24102.53771.24812.49502.88947.22031.13470.13470.17370.18971.13470.2180 2.0mm0.95332.60961.06021.89970.56831.06022.11302.41476.00980.96740.12660.14420.15750.96740.1787 1.5mm0.75692.06781.16581.50840.44190.84741.67561.89654.67200.74150.10150.11560.12590.78160.1409 1.2mm0.62501.70560.96751.25200.36130.70271.38481.55773.81570.65220.08370.09550.10420.65220.1167 增強型鋼st27×21.5st34.5×17st27.5×17st30.5×17st31.5×20.5st34.5×25st26.5×27.5st28.5×31st52.5×34.5st34.5×21st24.5×12st26×13st24.5×13.5st34.5×21st26×14 型材名稱br60se76/up76se76npz76nfr73sf78br66fr62sf106hs73/se73br73sf52st73hf80/se80sf54 實德主要型材增強型鋼慣性矩表iy (cm4)3.0mm0.98911.09462.20322.66181.70520.98911.09462.66183.68122.260025.12525.28513.989614.89483.38223.2259 2.5mm0.87760.96851.95412.35061.46920.87760.96852.35063.20451.975121.54234.61323.513512.84422.93592.8158 2.0mm0.77040.81971.52631.99150.96790.76880.81981.99152.67271.645517.53423.53422.974210.46572.73521.7911 1.5mm0.61600.65471.21911.58190.96790.61600.65471.55612.08801.242814.32642.98342.35238.07651.91441.4864 1.2mm0.52130.54231.01131.30820.80060.50960.54241.30821.70851.045010.91821.94051.98726.55581.57031.1618 ix (cm4)3.0mm0.15320.21720.62211.17380.21320.15320.21721.17383.42670.499413.86859.15340.31284.61551.58033.7487 2.5mm0.13470.18970.56671.05320.18270.13470.18971.05322.92150.431711.96417.93210.29484.04421.35223.1954 2.0mm0.12640.15760.48600.90530.11770.12650.15790.90532.38190.36399.81336.81330.26583.36371.24242.4942 1.5mm0.10120.12600.40090.73110.11770.10120.12600.79871.82290.28067.59305.03800.22512.64210.85251.9876 1.2mm0.89530.10380.33760.61040.09800.08360.10400.61041.47350.23246.17974.55360.19352.16920.69391.5530 增強型鋼st24.5×12st24.5×13.5st28×16.5st29×21st29×13st24.5×12st24.5×13.5st29×21st28.5×35st29.5×17.5st59×41st42×30st40×10st53×26st33×27st23.5×36.5 型材名稱br80nst80hs88/hf88shf88/se88sf57br88st88hf62/se62/hf95sf92sf66ds111df60hf108kt108sf80lk40 塑料窗抗風壓計算實例 計算說明:①按洞口標志尺寸計算,取最不利狀態; ②計算結果取玻璃、豎梃、橫梃中最小值表示。 一、兩扇推拉窗,5mm單玻。 1、門窗荷載分布圖及增強型鋼圖如圖3-3: 2、增強型鋼的慣性矩(用公式(10)計算): ix=(bh3-bh3)/12=(1.75×2.953-1.6×2.653)/12 =1.26cm4 3、把受荷單元的荷載作圖分四塊(如上圖),計算陰影部分的受荷面積: a1=(0.6+1.2)×0.3/2=0.27m2 k=300/1200=0.25 查表(1):k1=64.0 4、承載能力計算: (1)玻璃承載能力: 面積:a=0.6×1.2=0.72m2 代入式(8) 承載能力:wk=0.2×1×51.8/0.72=5.03kpa (2)豎直扇桿件承載能力: 按梯形荷載公式計算,將上述各值分別代入式(7)及表(1)公式中: wk=64ei/130al2 =64×2.1×106×1.26/130×1202×0.27 =3.35kpa d.結論:此窗抗風壓值為3.35kpa。 二、雙扇帶上亮平開窗,(5+9+5)mm中空玻璃。 1、門窗荷載分布圖及增強型鋼圖如圖3-4: 2、增強型鋼的慣性矩(用公式(10)計算): ix=(bh3-bh3)/12=(1.7×3.453-1.4×3.153)/12 =2.171cm4 3、把每個受荷單元的荷載作圖分四塊(如上圖),計算陰影部分的受荷面積: a1=(0.9+1.2)×0.15/2=0.1575m2 k1=150/1200=0.125 查表(1):k1´=69.05 a2=a3=0.6×0.3/2=0.09m2 k2=300/600=0.5 查表(1):k2´=60.0 a4=a5=(0.6+1.2)×0.3/2=0.27m2 k3=300/1200=0.25 查表(1):k3´=64.0 4、承載能力計算: (1)玻璃承載能力: 亮窗部分面積:a=0.3×1.2=0.36m2 代入式(8) 承載能力:wk=0.2×1.5×51.8/0.36=15.09kpa 開啟扇部分面積:a=1.2×1.2/2=0.72m2 代入式(8) 承載能力:wk=0.2×1.5×51.8/0.72=7.54kpa (2)豎梃承載能力: 按梯形荷載公式計算,將上述各值分別代入式(7)及表(1)公式中: wk=64ei/180al2 =64×2.1×106×2.171/180×1202×0.54 =2.08kpa (3)橫梃承載能力: fmax=f1+f2+f3=l/180(a) f1=wa1l3/k1ei(b) f2=w(a2+a3)l3/k2ei(c) f3=w(a4+a5)/2l3/48ei(d) 將各值分別代入(a)(b)(c)(d)式中:
將具體數值代入上式,得: wk=1.61kpa 結論:此窗抗風壓值為1.61kpa。
引自: http://www.menchuang168.com/sugang/shide/
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