支架立桿穩(wěn)定和地基承載力計(jì)算

1、遼寧聚成工程項(xiàng)目管理聯(lián)盟Liaoning JUCHENG engineering project management institute支架立桿穩(wěn)定和地基承載力計(jì)算 腳手架立桿底座和地基承載力計(jì)算是腳手架（支架）計(jì)算中的重要內(nèi)容。1 立桿底座計(jì)算1.1 支撐立桿的穩(wěn)定應(yīng)按下列公式計(jì)算（1）不考慮風(fēng)荷載時(shí)N/ Af（式1）（2）考慮風(fēng)荷載時(shí)N/A+Mw/Wf（式2）式中 N計(jì)算立桿段的軸向力計(jì)算值； 軸心受壓構(gòu)件的穩(wěn)定系數(shù)，應(yīng)按長(zhǎng)細(xì)比按下表選擇； 長(zhǎng)細(xì)比，l0/i； l0計(jì)算長(zhǎng)度，按規(guī)定計(jì)算； i立桿截面回轉(zhuǎn)半徑； A 立桿的截面面積； Mw計(jì)算立桿段由風(fēng)荷載設(shè)計(jì)值產(chǎn)生的彎矩，Mw=0.9&#

2、215;1.4Mwk； Mwk計(jì)算立桿段由風(fēng)荷載標(biāo)準(zhǔn)值產(chǎn)生的彎矩，按規(guī)定計(jì)算。 f鋼材的抗壓強(qiáng)度設(shè)計(jì)值，應(yīng)取f=205N/mm2； W立桿截面抗彎模量（cm2）。表1 軸心受壓構(gòu)件的穩(wěn)定系數(shù)012345678901.0000.9970.9950.9920.9890.9870.9840.9810.9790.976100.9740.9710.9680.9660.9630.9600.9580.9550.9520.949200.9470.9440.9410.9380.9360.9330.9300.9270.9240.921300.9180.9150.9120.9090.9060.9030.8990.8

3、960.8930.889400.8860.8820.8790.8750.8720.8680.8640.8610.8580.855500.8520.8490.8460.8430.8390.8360.8320.8290.8250.822600.8180.8140.8100.8060.8020.7970.7930.7890.7840.779700.7750.7700.7650.7600.7550.7500.7440.7390.7330.728800.7220.7160.7100.7040.6980.6920.6860.6800.6730.667900.6610.6540.6480.6410.6340

4、.6260.6180.6110.6030.5951000.5880.5800.5730.5660.5580.5510.5440.5370.5300.5231100.5160.5090.5020.4960.4890.4830.4760.4700.4640.4581200.4520.4460.4400.4340.4280.4230.4170.4120.4060.4011300.3960.3910.3860.3810.3760.3710.3670.3620.3570.3531400.3490.3440.3400.3360.3320.3280.3240.3200.3160.3121500.3080.3

5、050.3010.2980.2940.2910.2870.2840.2810.2771600.2740.2710.2680.2650.2620.2590.2560.2530.2510.2481700.2450.2430.2400.2370.2350.2320.2300.2270.2250.2231800.2200.2180.2160.2140.2110.2090.2070.2050.2030.2011900.1990.1970.1950.1930.1910.1890.1880.1860.1840.1821.2 立桿的計(jì)算長(zhǎng)度l0計(jì)算l0=k1 k2 (h+2a)式中 k1計(jì)算長(zhǎng)度附加系數(shù)，按表

6、2采用； k2考慮支架整體穩(wěn)定因素的單根立桿計(jì)算長(zhǎng)度附加系數(shù)，按表3采用。表2 單根立桿計(jì)算長(zhǎng)度附加系數(shù)k1步距h（m）h0.90.9h1.21.2h1.51.5h1.8k11.2431.1851.1671.163表3 立桿計(jì)算長(zhǎng)度附加系數(shù)k21.3 風(fēng)荷載標(biāo)準(zhǔn)值計(jì)算式中Wk風(fēng)荷載的標(biāo)準(zhǔn)值(kN/m2);µz風(fēng)壓高度變化系數(shù),按現(xiàn)行標(biāo)準(zhǔn)建筑結(jié)構(gòu)荷載規(guī)范(GB50009)規(guī)定采用;µs支架及模板系數(shù)風(fēng)荷載體型系數(shù),應(yīng)按表5規(guī)定采用;W0基本風(fēng)壓值(kN/m2),按現(xiàn)行國(guó)家標(biāo)準(zhǔn)建筑結(jié)構(gòu)荷載規(guī)范(GB50009)的規(guī)定采用,取重現(xiàn)期n=10對(duì)應(yīng)的風(fēng)壓值。表4 風(fēng)壓高度變化系數(shù)表5

7、 支架的風(fēng)荷載體系系數(shù)表6 遼寧地區(qū)城市風(fēng)壓值2 立桿地基承載力計(jì)算 N/AdKc fak式中 N立桿傳至基礎(chǔ)頂面的平均軸向力設(shè)計(jì)值； Ad立桿基礎(chǔ)的計(jì)算底面積，可按以下情況確定：工況Ad取值僅有立桿支座（支座直接放于地面上）取支座板的底面積在支座下設(shè)有厚度為5060mm的木墊板（或木腳手板）取Ad=a×b（a和b為墊板的兩個(gè)邊長(zhǎng)，且不小于200mm）在支座下采用枕木作墊木Ad按枕木的底面積計(jì)算當(dāng)一塊墊板或墊木上支承二根以上立桿Ad=1/n a×b（n為立桿數(shù)），（a和b為墊板的兩個(gè)邊長(zhǎng)，且不小于200mm）fak地基承載力特征值，按地勘報(bào)告選用，當(dāng)?shù)鼗鶠榛靥顣r(shí)乘以地基承載系數(shù)，以保證腳手架安全。Kc腳手架地基承載力調(diào)整系數(shù)。（1）當(dāng)?shù)鼗鶠榛靥钔習(xí)r，必須分層夯實(shí)，并應(yīng)考慮雨水滲透的影響。地基承載系數(shù)：對(duì)碎石土、砂土、回填土應(yīng)取0.4，對(duì)粘土取應(yīng)取0.5。當(dāng)回填土能嚴(yán)格按照操作規(guī)程施工，