1、 栏杆荷载:qf = 0.20kN/m 永久荷载分项系数: G = 1.20 可变荷载分项系数: Q = 1.40 准永久值系数: q = 0.50 4.材料信息: 混凝土强度等级: C20 fc = 9.60 N/mm2 ft = 1.10 N/mm2 Rc=25.0 kN/m3 ftk = 1.54 N/mm2 Ec = 2.55104 N/mm2 钢筋强度等级: HPB235 fy = 210 N/mm2 Es = 2.10105 N/mm2 保护层厚度:c = 20.0 mm Rs=20 kN/m3 受拉区纵向钢筋类别:光面钢筋 梯段板纵筋合力点至近边距离:as = 25.00 mm
2、支座负筋系数: = 0.25四、计算过程: 1. 楼梯几何参数: 踏步高度:h = 0.1500 m 踏步宽度:b = 0.2222 m 计算跨度:L0 = L1(b1b2)/2 = 2.00(0.200.20)/2 = 2.20 m 梯段板与水平方向夹角余弦值:cos = 0.829 2. 荷载计算( 取 B = 1m 宽板带): (1) 梯段板: 面层:gkm = (BB*h/b)*qm = (11*0.15/0.22)*1.70 = 2.85 kN/m 自重:gkt = Rc*B*(t/cosh/2) = 25*1*(0.10/0.8290.15/2) = 4.89 kN/m 抹灰:gk
3、s = RS*B*c/cos = 20*1*0.02/0.829 = 0.48 kN/m 恒荷标准值:Pk = gkmgktgksqf = 2.854.890.480.20 = 8.42 kN/m 恒荷控制: Pn(G) = 1.35*PkQ*0.7*B*q = 1.35*8.421.40*0.7*1*2.50 = 13.82 kN/m 活荷控制:Pn(L) = G*PkQ*B*q = 1.20*8.421.40*1*2.50 = 13.61 kN/m 荷载设计值:Pn = max Pn(G) , Pn(L) = 13.82 kN/m 3. 正截面受弯承载力计算: 左端支座反力: Rl = 1
4、5.20 kN 右端支座反力: Rr = 15.20 kN 最大弯矩截面距左支座的距离: Lmax = 1.10 m 最大弯矩截面距左边弯折处的距离: x = 1.10 m Mmax = Rl*LmaxPn*x2/2 = 15.20*1.1013.82*1.102/2 = 8.36 kNm 相对受压区高度:= 0.169123 配筋率:= 0.007731 纵筋(1号)计算面积:As = 579.85 mm2 支座负筋(2、3号)计算面积:As=*As = 0.25*579.85 = 144.96 mm2五、计算结果:(为每米宽板带的配筋) 1.1号钢筋计算结果(跨中) 计算面积As:579.
5、85 mm2 采用方案:d10100 实配面积: 785 mm2 2.2/3号钢筋计算结果(支座) 计算面积As:144.96 mm2d6140 202 mm2 3.4号钢筋计算结果d6200 141 mm2六、跨中挠度计算: Mk - 按荷载效应的标准组合计算的弯矩值 Mq - 按荷载效应的准永久组合计算的弯矩值 1.计算标准组合弯距值Mk: Mk = Mgk+Mqk = (qgk + qqk)*L02/8 = (8.42 + 2.500)*2.202/8 = 6.607 kN*m 2.计算永久组合弯距值Mq: Mq = Mgk+Mqk = (qgk + q*qqk)*L02/8 = (8.
6、42 + 0.50*2.500)*2.202/8 = 5.851 kN*m 3.计算受弯构件的短期刚度 Bs 1) 计算按荷载荷载效应的标准组合作用下,构件纵向受拉钢筋应力 sk = Mk/(0.87*h0*As) (混凝土规范式 8.1.33) = 6.607106/(0.87*75*785) = 128.932 N/mm 2) 计算按有效受拉混凝土截面面积计算的纵向受拉钢筋配筋率 矩形截面积: Ate = 0.5*b*h = 0.5*1000*100= 50000 mm2 te = As/Ate (混凝土规范式 8.1.24) = 785/50000 = 1.571% 3) 计算裂缝间纵向
7、受拉钢筋应变不均匀系数 = 1.1-0.65*ftk/(te*sk) (混凝土规范式 8.1.22) = 1.1-0.65*1.54/(1.571%*128.932) = 0.606 4) 计算钢筋弹性模量与混凝土模量的比值 E E = ES/EC = 2.10105/(2.55104) = 8.235 5) 计算受压翼缘面积与腹板有效面积的比值 f 矩形截面,f = 0 6) 计算纵向受拉钢筋配筋率 = As/(b*h0) = 785/(1000*75) = 1.047% 7) 计算受弯构件的短期刚度 BS BS = ES*As*h02/1.15*+0.2+6*E*/(1+ 3.5*f)(混
8、凝土规范式8.2.3-1)105*785*752/1.15*0.606+0.2+6*8.235*1.047%/(1+3.5*0.0) = 6.561102 kN*m2 4.计算受弯构件的长期刚度B 1) 确定考虑荷载长期效应组合对挠度影响增大影响系数 当=0时,=2.0 (混凝土规范第 8.2.5 条) 2) 计算受弯构件的长期刚度 B B = Mk/(Mq*(-1)+Mk)*BS (混凝土规范式 8.2.2) = 6.607/(5.851*(2.0-1)+6.607)*6.561102 = 3.480 5.计算受弯构件挠度 fmax = 5*(qgk+qqk)*L04/(384*B) = 5
9、*(8.42+2.500)*2.204/(384*3.480102) = 9.574 mm 6.验算挠度 挠度限值f0=L0/200=2.20/200=11.000 mm fmax=9.574mmf0=11.000mm,满足规范要求!七、裂缝宽度验算: 2.光面钢筋,所以取值Vi=0.7 3.C = 20 4.计算按荷载荷载效应的标准组合作用下,构件纵向受拉钢筋应力106/(0.87*75.00*785) 5.计算按有效受拉混凝土截面面积计算的纵向受拉钢筋配筋率 6.计算裂缝间纵向受拉钢筋应变不均匀系数 7.计算单位面积钢筋根数n n = 1000/s = 1000/100 = 10 8.计算
10、受拉区纵向钢筋的等效直径deq deq= (ni*di2)/(ni*Vi*di) = 10*102/(10*0.7*10) = 14 9.计算最大裂缝宽度 max =cr*sk/ES*(1.9*C+0.08*deq/te) (混凝土规范式 8.1.21) = 2.1*0.606*128.932/2.1105*(1.9*20+0.08*14/1.571%) = 0.0854 mm 0.30 mm,满足规范要求类型二L0 = L1b1/2b = 2.000.20/20.22 = 1.88 m Rl = 12.97 kN Rr = 12.97 kN Lmax = 0.94 m x = 0.94 m
11、= 12.97*0.9413.82*0.942/2 = 6.09 kN= 0.119990 配筋率:= 0.005485As = 411.39 mm2=*As = 0.25*411.39 = 102.85 mm2411.39 mm2102.85 mm2 = (8.42 + 2.500)*1.882/8 = 4.814 kN*m = (8.42 + 0.50*2.500)*1.882/8 = 4.263 kN*m = 4.814 = 93.930 N/mm = 1.1-0.65*1.54/(1.571%*93.930) = 0.422105*785*752/1.15*0.422+0.2+6*8.
12、235*1.047%/(1+3.5*0.0) = 7.717 = 4.814/(4.263*(2.0-1)+4.814)*7.717 = 4.093 = 5*(8.42+2.500)*1.884/(384*4.093 = 4.320 mm 挠度限值f0=L0/200=1.88/200=9.389 mm fmax=4.320mmf0=9.389mm,满足规范要求! = 2.1*0.422*93.930/2.1 = 0.0433 mm类型三 下平台宽: L2 = 300 mmL0 = L1L2(b1b2)/2 = 2.000.30(0.200.20)/2 = 2.50 m (2) 平台板:gkm = B*qm = 1*1.70 = 1.70 kN/mgkt = Rc*B*t = 25*1*0.10 = 2.50 kN/mgks = RS*B*c = 20*1*0.02 = 0.40 kN/mPk = gkmgktgksqf = 1.702.500.400.20 = 4.80 kN/m Pl(G) = 1.35*PkQ*0.7*B*q = 1.35*4.801.40*0.7*1*2.50 = 8.93 kN/mPl(L) = G*PkQ*B*q = 1.20*4.801.40*1*2.50 = 9.26 kN/mPl = max Pl(G) , Pl(L) = 9.26 kN/m
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