计算依据:
1、《建筑地基基础设计规范》GB50007-2011 2、《混凝土结构设计规范》GB50010-2010 3、《建筑结构荷载规范》GB50009-2012
一、基本参数
1、上部荷载参数
基础顶部柱子轴力设计值F(kN) 基础顶部柱子弯矩设计值My(kN·m) 基础顶部柱子剪力设计值Vy(kN) 基本组合分项系数Kc 200 50 10 1.35 基础顶部柱子弯矩设计值Mx(kN·m) 基础顶部柱子剪力设计值Vx(kN) 标准组合分项系数Ks 50 10 1.3 2、基础上部柱子参数 基础上部柱子截面类型 砼柱截面宽b(mm) 方柱 600 砼柱截面长a(mm) 800 3、基础参数 基础类型 基础底面长L×宽B×高h1(mm) 基础柱边面长dx×宽dy×高h3(mm) 混凝土强度等级 基础上部覆土厚度h′(m) 基础混凝土保护层厚度δ(mm) 阶梯形 3600×2800×400 600×300×400 C30 1.2 50 基础台阶数 基础二阶底面长L1×宽B1×高h2(mm) 基础埋置深度H1(m) 基础自重γc(kN/m3) 基础上部覆土的自重γ′(kN/m3) 三阶 2800×2000×400 2.4 24 17 4、地基参数 地基承载力特征值fak(kPa) 基础埋深地基承载力修正系数ηd 基础底面以上的土的加权平均重度γm(kN/m3) 170 1.6 18 基础宽度地基承载力修正系数ηb 0.3 基础底面以下的土的重度γ(kN/m3) 20 基础底面修正后的地基承载力特征值fa(kPa) 224.72 5、软弱下卧层
基础底面至软弱下卧层顶部的距离z(m) 软弱下卧层顶处修正后的地基承载力160 设计值faz(kPa) 2 地基压力扩散角θ(°) 23 二、计算简图
平面图
剖面图1-1
剖面图2-2
三、承台验算
1、基础受力 设计值计算: F=200KN
Mx′=Mx+H1×Vx=50+2.4×10=74kN·m My′=My+H1×Vy=50+2.4×10=74kN·m 标准值计算:(标准组合) Fk=Ks×F=1.3×200=260kN Mxk=Ks×Mx′=1.3×74=96.2kN·m Myk=Ks×My′=1.3×74=96.2kN·m 2、基础及其上土的自重荷载标准值:
Gk=L×B×(γc×h1+ (h′+h2+h3) ×γ′)+L1×B1×h2×(γc-γ′)+(dx×2+a ) ×(dy×2+b)×h3×(γc-γ′)=3.6×2.8×(24×0.4+ (1.2+0.4+0.4)
×17)+2.8×2×0.4×(24-17)+(0.6×2+0.8 ) ×(0.3×2+0.6)×0.4×(24-17)=461.888kN 3、基础底面压应力计算
pk = (Fk + Gk)/A=(260+461.888)/(2.8×3.6)=71.616kPa 基础底面抵抗矩:WX= BL2/6=2.8×3.62/6=6.048m3 基础底面抵抗矩:WY= LB2/6=3.6×2.82/6=4.704m3 ex=Mxk /(Fk+Gk)=96.2/(260+461.888)=0.133
pxkmax= (Fk + Gk)/A + |Mxk|/Wx=71.616+96.2/6.048=87.522kPa pxkmin= (Fk + Gk)/A - |Mxk|/Wx=71.616-96.2/6.048=55.71kPa px增= pxkmax-pk=15.906kPa px减= pk-pxkmin=15.906kPa
ey=Myk/(Fk+Gk)=96.2/(260+461.888)=0.133
pykmax= (Fk + Gk)/A + |Myk|/Wy=71.616+96.2/4.704=92.067kPa pykmin= (Fk + Gk)/A - |Myk|/Wy=71.616-96.2/4.704=51.165kPa py增= pykmax-pk=20.451kPa py减= pk-pykmin=20.451kPa
pkmax = pk+ px增+ py增=71.616+15.906+20.451=107.973kPa pkmin = pk- px减- py减=71.616-15.906-20.451=35.259kPa
基座反力图
1)轴心作用时地基承载力验算 Pk=71.616kPa≤fa=224.72kPa 满足要求!
2)偏心作用时地基承载力验算
Pkmax=107.973kPa≤1.2fa=1.2×224.72=269.664kPa 满足要求! 4、软弱下卧层验算
基础底面处土的自重压力值:pc= H1×γm=2.4×18=43.2kPa 下卧层顶面处附加压力值: pz=l b
×(pkmax-pc )/((b+2ztanθ)(l+2ztanθ))=3.6×2.8×(107.973-43.2)/((2.8+2×2×tan23)×(3.6+2×2×tan23))=27.399kPa
软弱下卧层顶面处土的自重压力值:pcz=z×γ=2×20=40kPa
作用在软弱下卧层顶面处总压力:pz+pcz=27.399+40=67.399kPa≤faz=160kPa
满足要求! 5、基础抗剪切验算
Pjmax= Kc×(pkmax-Gk /A) =1.35×(107.973-461.888/(3.6×2.8))=83.904kPa Pjmin=0kPa 1)第一阶验算
抗剪切计算简图一阶X向
抗剪切计算简图一阶y向
h0x=h1-(δ+φx/2) = 400-(50+10/2)=345mm βhx=(800/ h0x)0.25=1
Acx1= Lh0x=3600×345=1242000 mm2
Vx=0.7×βhx×ft ×Acx1=0.7×1×1.43×1242000=1243242N=1243.242kN≥pjmax ×L×(B-B1 )/2=83.904×3.6×(2.8-2)/2=120.822kN h0y=h1-(δ+φy /2)= 400-(50+10/2)=345mm βhy=(800/h0y)0.25=1
Acy1=Bh0y= 600×345=207000 mm2
Vy=0.7×βhy×ft×Acy1=0.7×1×1.43×207000=207207N=207.207kN≥pjmax×B×(L- L1 )/2=83.904×2.8×(3.6-2.8)/2=93.972 kN 满足要求! 2)第二阶验算
抗剪切计算简图二阶X向
抗剪切计算简图二阶y向
h0x=h1-(δ+φx/2)+ h2 =400-(50+10/2)+400=745mm βhx=(800/h0x)0.25=1
Acx2 =L×(h0x-h2) + L1 ×h2=3600×(745-400)+2800×400=2362000 mm2
Vx=0.7×βhx×ft×Acx2=0.7×1×1.43×2362000=2364362N=2364.362kN≥pjmax×L×(B-(b+2dy ))/2=83.904×3.6×(2.8-0.6-2×0.3)/2=241.644 kN h0y=h1-(δ+φy/2)+ h2 =400-(50+10/2)+400=745mm βhy=(800/h0y)0.25=1
Acy2 =B×(h0y-h2) + B1 ×h2=2800×(745-400)+2000×400=1766000 mm2
Vy=0.7×βhy×ft×Acy2=0.7×1×1.43×1766000=1767766N=1767.766kN≥pjmax×B×(L-(a+2dx ))/2=83.904×2.8×(3.6-0.8-2×0.6)/2=187.945 kN 满足要求!
3)第三阶验算
抗剪切计算简图三阶X向
抗剪切计算简图三阶y向
h0x=h1-(δ+φx/2) + h2+ h3=400-(50+10/2)+400+400=1145mm βhx=(800/h0x)0.25=0.914
Acx3=L×(h0x-h2-h3)+L1×h2+(a+2dx)×h3=3600×(1145-400-400)+2800×400+(800+2×600)×400=3162000 mm2
Vx=0.7×βhx×ft×Acx3=0.7×0.914×1.43×3162000=2892958.068N=2892.958kN≥pjmax ×L×(B-b)/2=83.904×3.6×(2.8-0.6)/2=332.26kN
h0y=h1-(δ+φy/2) + h2+ h3= 400-(50+10/2)+400+400=1145mm βhy=(800/h0y)0.25=0.914
Acy3=B×(h0y-h2-h3)+B1×h2+(b+2dy)×h3=2800×(1145-400-400)+2000×400+(600+2×300)×400=2246000 mm2
Vy=0.7×βhy×ft×Acy3=0.7×0.914×1.43×2246000=2054896.844N=2054.897kN≥pjmax
×B×(L-a)/2=83.904×2.8×(3.6-0.8)/2=328.904kN 满足要求! 6、基础抗冲切验算 1)第一阶验算
k=(L1 -B1 )/2=(2800-2000)/2=400mm X方向验算:
抗冲切验算一阶X向
abx=2h0x +L1=2×345+2800=3490 mm≤L=3600mm,取abx=2h0x+L1=3490 mm y1= L/2-k=3600/2-400 =1400 mm≥B/2=1400 mm x1=2×(B/2+k) =2×(2800/2+400) =3600 mm y2=h0x +B1/2=345+2000/2 =1345 mm
Alx=(B/2-y2)(abx+x1)/2 = (2800/2-1345)( 3490+3600)/2=194975 mm2 Y方向验算:
抗冲切验算一阶y向
aby=2h0y+B1=2×345+2000=2690mm≤B=2800mm,取aby=2h0y+B1=2690mm x1= B/2+k= 2800/2+400=1800 mm≥3600/2=1800 mm y1=2×(L/2-k) =2×(3600/2-400)=2800 mm x2= h0y +L1/2=345+2800/2=1745mm
Aly= (L/2-x2)(aby+y1)/2 = (3600/2-1745)(2690+2800)/2=150975mm2
amx=(at +abx)/2=(2800+3490)/2=3145mm amy=(at +aby)/2 =(2000+2690)/2=2345mm Aq1x=amx×h0x=3145×345=1085025 mm2 Aq1y=amy×h0y=2345×345=809025 mm2
Flx=0.7×βhp ×ft ×Aq1x=0.7×1×1.43×1085025=1086110.025N=1086.11kN≥pjmax ×Alx=83.904×0.001×194975=16359.182N=16.359kN
F1y=0.7×βhp×ft ×Aq1y=0.7×1×1.43×809025=809834.025N=809.834kN≥pjmax ×Aly=83.904×0.001×150975=12667.406N=12.667kN
满足要求! 2)第二阶验算
k=((a+2dx) -(b+2dy) )/2=((800+2×600)-(600+2×300))/2=400mm X方向验算:
抗冲切验算二阶X向
abx=2h0x +(a+2dx)=2×745+(800+2×600)=3490 mm≤L=3600mm,取abx=2h0x+(a+2dx)=3490 mm
y1= L/2-k=3600/2-400 =1400 mm≥B/2=1400 mm x1=2×(B/2+k) =2×(2800/2+400) =3600 mm y2=h0x +(b+2dy)/2=745+(600+2×300)/2 =1345 mm
Alx=(B/2-y2)(abx+x1)/2 = (2800/2-1345)( 3490+3600)/2=194975 mm2 Y方向验算:
抗冲切验算二阶y向
aby=2h0y+(b+2dy)=2×745+(600+2×300)=2690mm≤B=2800mm,取aby=2h0y+(b+2dy)=2690mm
x1= B/2+k= 2800/2+400=1800 mm≥3600/2=1800 mm y1=2×(L/2-k) =2×(3600/2-400)=2800 mm x2= h0y +(a+2dx)/2=745+(800+2×600)/2=1745mm
Aly= (L/2-x2)(aby+y1)/2 = (3600/2-1745)(2690+2800)/2=150975mm2
amx=(at +abx)/2=(2000+3490)/2=2745mm amy=(at +aby)/2 =(1200+2690)/2=1945mm Aq1x=amx×h0x=2745×745=2045025 mm2 Aq1y=amy×h0y=1945×745=1449025 mm2
Flx=0.7×βhp ×ft ×Aq1x=0.7×1×1.43×2045025=2047070.025N=2047.07kN≥pjmax ×Alx=83.904×0.001×194975=16359.182N=16.359kN
F1y=0.7×βhp×ft ×Aq1y=0.7×1×1.43×1449025=1450474.025N=1450.474kN≥pjmax ×Aly=83.904×0.001×150975=12667.406N=12.667kN
满足要求! 3)第三阶验算
k=(a -b )/2=(800-600)/2=100mm X方向验算:
抗冲切验算三阶X向
abx=2h0x +a=2×1145+800=3090 mm≤L=3600mm,取abx=2h0x+a=3090 mm y1= L/2-k=3600/2-100 =1700 mm≥B/2=1400 mm x1=2×(B/2+k) =2×(2800/2+100) =3000 mm y2=h0x +b/2=1145+600/2 =1445 mm
Alx=(B/2-y2)(abx+x1)/2 = (2800/2-1445)( 3090+3000)/2=-137025 mm2 因为Alx<0,即Alx不存在,故取Alx=0 Y方向验算:
抗冲切验算三阶y向
aby=2h0y+b=2×1145+600=2890mm> B=2800mm,取aby=B=2800mm x2= h0y +a/2= 1145 +800/2=1545mm
Aly= (L /2- x2) ×aby= (3600 /2- 1545) ×2800=714000mm2
amx=(at +abx)/2=(800+3090)/2=1945mm amy=(at +aby)/2 =(600+2800)/2=1700mm Aq1x=amx×h0x=1945×1145=2227025 mm2 Aq1y=amy×h0y=1700×1145=1946500 mm2
Flx=0.7×βhp ×ft ×Aq1x=0.7×0.914×1.43×2227025=2037536.351N=2037.536kN≥pjmax ×Alx=83.904×0.001×0=0N=0kN
F1y=0.7×βhp×ft ×Aq1y=0.7×0.914×1.43×1946500=1780880.101N=1780.88kN≥pjmax ×Aly=83.904×0.001×714000=59907.456N=59.907kN 满足要求!
四、承台配筋计算
承台底部X轴向配筋 HRB335Ф10@120 承台底部Y轴向配筋 HRB335Ф10@110
基础底板受力配筋图
Pj= Kc ×(pk-Gk /A) =1.35×(71.616-461.888/(3.6×2.8))=34.822kPa 1)第一阶验算
M1x=1/48[(pjmax+ pj) ×(2L+ L1)+ (pjmak-pj) ×L] ×(B -B1)2 =1/48×[(83.904+ 34.822) × (2×3600+ 2800)+ (83.904-34.822 ) ×3600] ×(2800- 2000)2=18.186 kN·m
M1y=1/48[(pjmax+ pj) ×(2B+ B1)+ (pjmak-pj) ×B] ×(L -L1)2 =1/48×[(83.904+ 34.822) × (2×2800+ 2000)+ (83.904-34.822 ) ×2800] ×(3600- 2800)2=13.863 kN·m Asx1=M1x/(0.9×fyx ×h0x ) =18.186×106/(0.9×300×345)=195.233mm2 Asy1=M1y/(0.9×fyy ×h0y ) =13.863×106/(0.9×300×345)=148.824mm2 2)第二阶验算
M2x=1/48[(pjmax+ pj) ×(2L+ (a+2dx))+ (pjmak-pj) ×L] ×(B -(b+2dy))2 =1/48×[(83.904+ 34.822) × (2×3600+ (800+2×600))+ (83.904-34.822 ) ×3600] ×(2800- (600+2×300))2=67.679 kN·m
M2y=1/48[(pjmax+ pj) ×(2B+ (b+2dy))+ (pjmak-pj) ×B] ×(L -(a+2dx))2
=1/48×[(83.904+ 34.822) × (2×2800+ (600+2×300))+ (83.904-34.822 ) ×2800] ×(3600- (800+2×600))2=50.388 kN·m
Asx2=M2x/(0.9×fyx ×h0x ) =67.679×106/(0.9×300×745)=336.46mm2 Asy2=M2y/(0.9×fyy ×h0y ) =50.388×106/(0.9×300×745)=250.5mm2 3)第三阶验算
M3x=1/48[(pjmax+ pj) ×(2L+ a)+ (pjmak-pj) ×L] ×(B -b)2 =1/48×[(83.904+ 34.822) × (2×3600+ 800)+ (83.904-34.822 ) ×3600] ×(2800- 600)2=113.589 kN·m
M3y=1/48[(pjmax+ pj) ×(2B+ b)+ (pjmak-pj) ×B] ×(L -a)2 =1/48×[(83.904+ 34.822) × (2×2800+ 600)+ (83.904-34.822 ) ×2800] ×(3600- 800)2=142.677 kN·m Asx3=M3x/(0.9×fyx ×h0x ) =113.589×106/(0.9×300×1145)=367.424mm2 Asy3=M3y/(0.9×fyy ×h0y ) =142.677×106/(0.9×300×1145)=461.514mm2
Asx=max(Asx1,Asx2,Asx3)=max(195.233, 336.46,
367.424)=367.424mm2≤ASX=[(2800/120) +1]×3.14×102/4=1910.167 mm2 Asy=max(Asy1,Asy2,Asy3)=max(148.824,250.5,
461.514)=461.514mm2≤ASY=[(3600/110) +1]×3.14×102/4=2647.591 mm2 满足要求!
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