截面设计本工程框架抗震级别为三级根据延性框架设计准则,截面设计时,应按照“强柱弱梁”、“强剪弱弯”原则,对内力进行调节框架梁框架梁正截面设计非抗震设计时,框架梁正截面受弯承载力为: (9-1-1)抗震设计时,框架梁正截面受弯承载力为: (9-1-2)因此,可直接比较竖向荷载作用下弯矩组合值M和水平地震作用下弯矩组合值M乘以抗震承载力调节系数后gRE的大小,取较大值作为框架梁截面弯矩设计值即 (9-1-3)比较39和表43中的梁端负弯矩,可知,各跨梁端负弯矩均由水平地震作用控制故表39中弯矩设计值来源于表43,且为乘后来的值进行正截面承载力计算时,支座截面按矩形截面计算;跨中截面按T形截面计算T形截面的翼缘计算宽度应按下列状况的最小值取用AB跨及CD跨:=7.5/3=2.5m; ,故取=1.86m鉴别各跨中截面属于哪一类T型截面:一排钢筋取=700-40=660mm,两排钢筋取=700-65=635mm,则=14.3×1860×130×(660-130/2)=2057.36kN.m该值不小于跨中截面弯矩设计值,故各跨跨中截面均属于第一类T形截面。
BC跨:=3.0/3=1.0m;=0.3+8.4-0.3=8.4m;;,故取=1m鉴别各跨中截面属于哪一类T型截面:取=550-40=510mm,则=14.3×1000×130×(510-130/2)=827.26kN.m该值不小于跨中截面弯矩设计值,故各跨跨中截面均属于第一类T形截面各层各跨框架梁纵筋配筋计算详见表49及表50表格49 各层各跨框架梁上部纵筋配筋计算层号AB跨BC跨CD跨-MABz-MABy-MBCz-MBCy-MCDz-MCDy4负弯矩M(kN·m)-213.6-181.8-188.86-188.86-181.18-213.60.1140.0970.1010.1010.0970.1140.1210.1020.1070.1070.1020.1210.9710.9490.9470.9470.9490.971配筋As()925.84803.52839.35839.35803.52925.84实配钢筋3C203C203C203C203负弯矩M(kN·m)-370.84-319.2-347.48-347.48-319.92-370.84 续表49层号AB跨BC跨CD跨-MABz-MABy-MBCz-MBCy-MCDz-MCDy30.1980.1710.1860.1860.1710.1980.2230.1890.2080.2080.1890.2230.8880.9060.8960.8960.9060.888配筋As()1757.631486.61632.211632.211486.161757.63实配钢筋4C254C254C254C252负弯矩M(kN·m)-452.60-445.3-500.02-500.02-445.63-452.600.2600.2580.2890.2890.2580.2620.3100.3040.350.350.3040.310.8450.8480.8250.8250.8480.845配筋As()2343.052298.12651.292651.292298.812343.05实配钢筋4C25+2C204C25+2C224C25+2C224C25+2C201负弯矩M(kN·m)-610-491.9-557.04-557.04-491.69-6100.3530.2840.3220.3220.2840.3530.4580.3430.4030.4030.3430.4580.7710.8290.7980.7980.8290.771配筋As()3460.982594.43053.5630530562594.543460.98实配钢筋4C25+4C224C25+4C204C25+4C204C25+4C22表格50 各层各跨框架梁下部纵筋配筋计算层号AB跨BC跨CD跨MABzMAByMAB中MBCzMBCyMCDzMCDyMCD中4正弯矩M(kN·m)113.5342.92196.2778.3978.3942.92113.53196.270.0610.0230.1050.070.070.0230.0610.1050.0630.0230.1110.0730.0730.0230.0630.1110.9680.9880.9440.9620.9620.9880.9680.944配筋As(mm2)493.62182.83875.06443.83443.83182.83493.62875.06实配钢筋3C203C183C203正弯矩M(kN·m)212.59147.58253.44218.57218.57147.58212.59253.440.1140.0790.1360.1960.1960.0790.1140.1360.1210.0820.1470.2200.2200.0820.1210.1470.9390.9490.9060.8740.8740.9490.9390.906配筋As(mm2)952.86647.681177.341362.091362.09647.68952.861177.34实配钢筋2C25+1C203C252C25+1C202正弯矩M(kN·m)297.13273.37254.36371.00371.00273.37297.13254.360.1590.1460.1360.3680.3680.1460.1590.1360.1740.9210.9270.7570.7570.9210.1740.9270.9130.9210.9270.7570.7570.9210.9130.927配筋As(mm2)1369.711349.241154.842669.352669.351349.241369.711154.84实配钢筋3C254C25+2C223C251正弯矩M(kN·m)455.71321.43256.51428.13428.13321.43455.71256.51 续表501层号AB跨BC跨CD跨MABzMAByMAB中MBCzMBCyMCDzMCDyMCD中0.2630.1860.1480.3490.3490.1860.2630.1480.3120.2080.9120.7750.7750.2080.3120.9120.8440.8960.9120.7750.7750.8960.8440.912配筋As(mm2)2361.941569.291230.362868.252868.251569.292361.941230.36实配钢筋4C25+2C204C25+4C204C25+2C20注:1. 表中弯矩带“*”者由竖向荷载控制,弯矩设计值均来源于表39。
2. 表中弯矩不带“*”者均由水平地震作用控制,弯矩设计值来源于表43,且为乘以gRE后的值3. BC跨跨中弯矩较小,表中未列出9.1.2 框架梁斜截面设计按照“强剪弱弯” 原则,考虑地震作用组合时的梁剪力设计值应按式(9-1-4)计算,为简化计算,近似按下式拟定梁剪力设计值 (9-1-4)也即将表45中的剪力组合值放大1.1倍,作为梁端剪力设计值1)剪压比验算无地震作用组合时,AB跨及CD跨梁的最大剪力在CD跨首层左端,Vmax=183.62kN;BC跨各层梁的最大剪力在五层右端,Vmax= 29.99kN,根据式(9-1-5),有AB跨及CD跨:BC跨: 有地震作用组合时,AB跨及CD跨梁的最大剪力在CD跨首层左端,=353.07×1.1 =388.38kN;BC跨各层梁的最大剪力在首层右端 ,=469.48×1.1=516.43kN,各梁跨高比均不小于2.5,根据式(9-1-6),有AB跨及CD跨:BC跨: 各跨层各层梁剪压比均满足规定2)箍筋计算为简化计算,先根据“强剪弱弯”的规定,按加密区构造规定设立箍筋,计算其受剪承载能力,然后与最大剪力设计值进行比较,局限性者再作调节。
加密区箍筋取双肢f,8@100,各跨受剪承载能力计算如下:无地震作用组合时,根据(9-1-7)式即:AB跨及CD跨: BC跨: 有地震作用组合时,根据公式(9-1-8)AB跨及CD跨:gBC跨:即,除BC跨外,各跨各层梁箍筋均满足规定进一步分析计算可知,BC跨首层及二层需加大箍筋直径,采用双肢f,10@100其他各层仍采用双肢,8@100AB跨及CD跨非加密区箍筋取双肢,8@200,BC跨全长加密最小配箍率根据公式(9-1-9):满足最小配箍率规定9.2 框架柱按照“强柱弱梁”原则,考虑地震作用组合时的柱端弯矩设计值计算,实际就是将表46~表49中的柱端弯矩设计值乘以放大系数1.19.2.1 轴压比验算考虑地震作用组合时,底层柱最大轴力为C柱,;混凝土强度:C30轴压比 柱轴压比满足规定9.2.2 正截面受弯承载力计算根据柱端内力组合值选用最不利内力设计值,并选用柱上端和下端内力设计值的较大值作为截面配筋的计算根据选用内力时,应先求得柱的界线受压轴力,以拟定柱各截面的偏心受压状态柱同一截面分别承受正反向弯矩,故采用对称配筋混凝土强度:C30;钢筋强度:HRB400,因此界线相对受压区高度根据公式(9-2-1)计算,即:则界线受压轴力为:本工程中,柱截面控制内力均来自于有地震作用组合工况。
因此,荷载组合效应需乘以承载力抗震调节系数当截面轴力设计值g时,截面为大偏心受压状态;当截面轴力设计值g时,截面为小偏心受压状态但无论哪种偏心受压状态,轴力相近,则弯矩越大,配筋量越大因此,大偏心受压时,应选用弯矩较大、而轴力较小的内力组;小偏心受压时,应选用轴力较大且弯矩也较大的内力组此外,对不能明显判断的内力组,则应进行配筋量的比较对于多层框架,顶层或顶部两层柱常属于大偏心受压状态,其配筋由计算拟定;中间若干层也属于大偏心受压状态,但配筋一般是构造配筋,底层或底部两层柱在不同的内力组合工况下,偏心受压状态也许不同,应分别计算其配筋量,并取最大值1、大偏心受压状态对称配筋的大偏心受压柱,配筋按下式计算:当x≤2as′ 时, (9-2-1)当x>2as′ 时, (9-2-2)2、小偏心受压状态对称配筋的小偏心受压柱,配筋按下式计算: (9-2-3) (9-2-4)各柱配筋计算详见表51~表54。
表格51 A柱正截面控制内力及配筋计算层号4321内力弯矩M151.37277.02279.30811.90轴力N274.71593.83927.171189.36轴压比0.0390.0850.1320.170g0.750.750.750.8(mm)606.12513.15331.36750.90ea=max(20,h/30)(mm)23.3323.3323.3323.33ei = e0 + ea 629.45536.48354.69774.23l0=1.25H, 1.0H(首层)(mm)48754875487552001 = 0.5fcA/(gRE N)(≤1.0)1.01.01.01.02 =1.15 - 0.01 l0/h(≤1.0)1.01.01.01.01.0391.0461.0691.036(mm)(2as′=80)20.58<2as′44.49<2as′69.47<2as′95.05>2as′偏心受压状态大偏压大偏压大偏压大偏压As (mm2)317.54501.16190.06<0r(mm2)980980980980初选钢筋4C204C204C204C20表格52 B柱正截面控制内力及配筋计算层号4321内力弯矩M195.79524.50671.28672.54轴力N322.95647.59885.051108.54轴压比m0.0460.0920.1260.1580.750.750.750.80(mm)666.88890.92834.31667.36ea=max(20,h/30)(mm)23.3323.3323.3323.33ei = e0 + ea 690.21914.25857.64690.69l0=1.25H, 1.0H(首层)(mm)4875487548755200z1 = 0.5fcA/(gRE N)(≤1.0)1.01.01.01.0z 2=1.15 - 0.01 l0/h(≤1.0)1.01.01.01.01.0361.0271.0291.040(mm)(2as′=80)24.2<2as′48.5<2as′66.3<2as′88.5>2as′偏心受压状态大偏压大偏压大偏压大偏压As (mm2)439.561368.591702.621529.77(mm2)980980980980初选钢筋4C204C224C254C25表格53 C柱正截面控制内力及配筋计算层号4321内力弯矩M195.79524.50671.28672.54轴力N322.95647.59885.051108.54轴压比0.0460.0920.1260.1580.750.750.750.80(mm)666.88890.92834.31667.36ea=max(20,h/30)(mm)23.3323.3323.3323.33ei = e0 + ea 690.21914.25857.64690.69l0=1.25H, 1.0H(首层)(mm)4875487548755200z1 = 0.5fcA/(gRE N)(≤1.0)1.01.01.01.0z2 =1.15 - 0.01 l0/h(≤1.0)1.01.01.01.01.0361.0271.0291.040(mm)(2as′=80)24.2<2as′48.5<2as′66.3<2as′88.5>2as′偏心受压状态大偏压大偏压大偏压大偏压As (mm2)439.561368.591702.621529.77(mm2)980980980980初选钢筋4C204C224C254C25表格 54 D柱正截面控制内力及配筋计算层号4321内力弯矩M151.37277.02279.30811.90轴力N274.71593.83927.171189.36轴压比0.0390.0850.1320.1700.750.750.750.8(mm)606.12513.15331.36750.90ea=max(20,h/30)(mm)23.3323.3323.3323.33ei = e0 + ea 629.45536.48354.69774.23l0=1.25H, 1.0H(首层)(mm)4875487548755200z = 0.5fcA/(gRE N)(≤1.0)1.01.01.01.0z =1.15 - 0.01 l0/h(≤1.0)1.01.01.01.01.0391.0461.0691.036(mm)(2as′=80)20.5<2as′44.4<2as′69.4<2as′95.0>2as′偏心受压状态大偏压大偏压大偏压大偏压As (mm2)317.54501.16190.06<0(mm2)980980980980初选钢筋4C204C204C204C209.2.3 斜截面受剪承载力计算按照“强剪弱弯”原则,考虑地震作用组合时的柱端剪力设计值计算,实际就是将表45~表48中的柱端剪力设计值先按柱端弯矩设计值的调节系数1.1进行放大(满足强柱弱梁),再乘以“强剪弱弯”的放大系数1.1,即放大1.1×1.1=1.21倍。
1、剪压比验算二层C柱剪力最大:|Vmax| =315.01×1.21=381.16kN取=700-40=660mm,则柱截面尺寸满足规定2、箍筋配备抗震设计时,各柱最大轴压比、配箍特性值、最小体积配筋率见表55表格55 柱体积配箍率层 号4321A柱最大轴力Nmax(kN)2393.191711.371086.71498.91最大轴压比=Nmax/(fcA)0.3420.2440.1550.071最小配箍特性值0.090.080.080.08最小体积配箍率0.48%0.42%0.42%0.42%B柱最大轴力Nmax(kN)3075.592191.941343.13593最大轴压比=Nmax/(fcA)0.4390.3130.1920.085最小配箍特性值0.110.090.080.08最小体积配箍率0.58%0.48%0.42%0.42%C柱最大轴力Nmax(kN)3075.592191.941343.13593最大轴压比=Nmax/(fcA)0.4390.3130.1920.085最小配箍特性值0.110.090.080.08最小体积配箍率0.58%0.48%0.42%0.42%D柱最大轴力Nmax(kN)2393.191711.371086.71498.91最大轴压比=Nmax/(fcA)0.3420.2440.1550.071最小配箍特性值0.090.080.080.08最小体积配箍率0.48%0.42%0.42%0.42%根据柱端加密区的箍筋配备规定,初步拟定柱加密区箍筋取井字箍,8@100,非加密区取,8@200。
则加密区实际体积配筋率为:对照表55,可知,除C柱首层外,上述箍筋配备均可满足规定实际配箍时为简化类型,略作调节后,配备如下:各柱首层加密区箍筋取井字箍f,,10@100,非加密区取f,,10@200,二层以上加密区箍筋取井字箍f,,8@100,非加密区取f,,8@200各柱加密区范畴按构造规定:首层柱底端取基本顶面至±0.000以上1260mm,柱顶端取850mm,其他各层柱柱端均取700mm3、箍筋验算按最大剪力设计值计算二层C柱剪力最大:|Vmax| =315.01×1.21=381.16kN剪跨比l=2.35,相应轴力:N=936.65kN<0.3fcA=0.3×14.3×7002=2102.1kN,取N=2102.1kN柱剪力在整个层高范畴内是不变的,故验算柱斜截面强度时应取非加密区的箍筋间距593.01kN>|Vmax| =381.16kN(满足规定)非抗震设计时,各柱剪力较小,不需计算,按上述构造配备即可满足规定10.4现浇板设计本工程采用梁板整体现浇构造,板厚130mm,混凝土采用C30,钢筋采用HRB400级钢筋,在设计中,按弹性理论计算,各板区格的弯距而进行配筋计算。
10.4.1楼面板的内力及截面配筋计算 图 1 现浇板区格布置图(部分)1、设计参数 边横梁:300mm×700mm、中横梁:300mm×600mm、纵梁300mm×800mm钢筋混凝土现浇板,厚130mm,混凝土采用C30( fc=14.3N/ ),Ⅲ级钢筋fy=360N/表格57 楼面板荷载设计值区格g+q/2q/2g+qA、C5.58+4.55/2=7.864.55/2=2.285.58+4.55=10.13B、D、E4.91+3.25/2=6.543.25/2=1.624.91+3.25=8.16F5.74+3.25/2=7.363.25/2=1.626.89+3.25=10.14计算跨度内跨,边跨A区格板周边固支,查表可得方向跨中弯矩系数分别为0.04、0.0038,支座弯矩系数分别为-0.0829、-0.0570;周边简支时跨中弯矩系数为0.0965、0.0174对边区格板的简支边,取表格58 按弹性理论计算的弯矩值ABCDEF34.233.853.84.28.47.753.857.757.757.750.3570.5420.7800.4970.4900.5414.937.293.788.246.227.881.592.552.272.591.932.73-7.56-11.86-6.43-15.49-9.83-14.74-5.2000000-7.56-11.86-6.430-9.83-14.74-5.20-8.20-5.18-10.33-6.70-10.22、截面设计截面有效高度:一类环境类别板的最小混凝土保护层厚度15mm,假定选用,10钢筋方向方向支座截面的。
截面设计弯矩因楼盖周边有梁与板整浇,故所有区格的弯矩减少 20%截面配筋计算成果及配筋成果列于下表中表格59 双向板截面配筋截面m最小配筋面积配筋实际跨中A1100.8×4.93=3.9499.89260C8@1802791000.8×1.59=1.2735.89260C8@180279B1100.8×7.29=5.83147.81260C8@1802791000.8×2.25=1.850.10260C8@180279C1100.8×3.78=3.0276.49260C8@1802791000.8×2.27=1.8256.66260C8@180279D1100.8×8.24=6.59167.25260C8@1802791000.8×2.59=2.0757.62260C8@180279E1100.8×6.22=4.98138.89260C8@1802791000.8×1.93=1.5442.86260C8@180279F1100.8×7.88=6.30159.89260C8@1802791000.8×2.73=2.1860.68260C8@180279支座A-B1100.8×7.56=6.05153.70260C8@180279A-A1000.8×5.20=4.16105.47260C8@180279A-C1000.8×5.18=4.14104.96260C8@180279B-E1100.8×15.49=12.39316.04260C8@150335C-E1000.8×10.33=8.26210.06260C8@180279B-G1100.8×9.83=7.86199.68260C8@180279A-G1000.8×6.70=5.36135.90260C8@180279B-H1100.8×14.74=11.79326.81260C8@150335A-H1000.8×10.20=8.16207.30260C8@18027910.4.2屋面板的内力及截面配筋计算计算跨度内跨,边跨A区格板周边固支,查表可得方向跨中弯矩系数分别为0.04、0.0038,支座弯矩系数分别为-0.0829、-0.0570;周边简支时跨中弯矩系数为0.0965、0.0174。
对边区格板的简支边,取表格60 按弹性理论计算的弯矩值ABCDEF34.233.853.84.28.47.753.857.757.757.750.3570.5420.7800.4970.4900.5413.264.992.015.124.214.990.781.581.211.711.181.58-4.99-9.72-4.24-10.22-8.06-9.72-3.4300000-4.99-9.72-4.240-8.06-9.72-3.43-6.73-3.42-6.81-5.50-6.73屋面板弯矩不不小于楼面板弯矩两者相差很小因此屋面板配筋与楼面板配筋相似。