223.99KPa≤1.2fa＝1.2×239＝286.8KPa154.23 Pkmax＋Pkmin223.99＋154.23PK＝＝＝189.11KPa＜fa＝239KPa22
＝故持力层满足要求
（五）基础高度验算。现选用混凝土强度等级C20.钢筋HPB235.
2查得混凝土C20 ft?1.1N/mm2.钢筋HPB235 fy?210N/mm
地基净反力
G1.35GKPjmax＝Pmax－＝1.35Pmax－＝AA1.35×20×4.86×1.225﹙1.35×223.99－﹚KPa?269.31KPa4.86
G1.35GKPjmin＝Pmin－＝1.35Pmin－＝AA1.35×20×4.86×1.225﹙1.35×154.23－﹚KPa?175.14KPa4.86
设h=650mm.有垫层基础.则h0=650-40=610mm；下阶
基础高度h1=350mm,上阶h01=310mm；az1=1200mm.bz1=800mm。及配筋如图1-4
. .
图1-4基础高度及配筋图 柱边截面：
bz＋2h0＝0.45＋2×0.61＝1.67m＜b＝1.8m A2＝﹙bz＋h0﹚h0＝﹙0.45+0.61﹚×0.61＝0.65㎡
符合要求
变阶处截面：
Lacbbc2A1＝﹙－－h0﹚b－﹙－－h0﹚22222.70.451.80.452＝﹙－－0.61﹚×1.8－﹙－－0.61﹚＝0.923㎡ 2222F1＝A1Pjmax＝0.923×269.31KN＝248.57KN 0.7βhpftA2＝0.7×1.0×1100×0.65KN＝500.5KN＞F1＝248.57KN
bz1?2h01?0.8?2?0.31?1.42m﹤b?1.6m
babbA1?(?z1?h01)b?(?z1?h01)2 22222.41.21.60.8?[(??0.31)?1.6?(??0.31)2]m2?0.4559m22222
A2?(bz1?h01)h01?[(0.8?0.31)?0.31]?0.3441m2
F1?A1pjmax?(0.4559?279.99)kN?127.65kN 0.7?hpftA2?0.7?1.0?1100?0.3441?264.96kN?F1?127.65kN符合要求
. .
（六）底板配筋计算
1、计算基础长边方向. Ⅰ—Ⅰ截面
pjI?pjmin?l?az(pjmax?pjmin)2l2.4?0.5?[127.33?(279.99?127.33)]kN/m2?219.56kN/m22?2.41M1?(l?az)2(2b?bz)(pjmax?pj1) 48
1?[(2.4?0.5)2(2?1.6?0.35)(279.99?219.56)]kN?m?133.38kN?m 48 MI133.38?106AsI??mm2?1156.90mm2 0.9fyh00.9?210?610
Ⅲ—Ⅲ截面
1 MⅢ?(l?az1)2(2b?bz1)(pjmax?pjI)48
1 ?(2.4?1.2)2(2?1.6?0.80)(279.99?241.83)?62.62kN?m48
l?az1 pjI?pjmin?(pjmax?pjmin)2l
2.4?1.2 ?127.33?(179.99?127.33)?241.83kN/m22?2.4
MⅢ62.62?10622A??mm?1068mmsⅢ 0.9fyh00.9?210?310
比较AsI和AsⅢ.应按AsI配筋.在1.6m宽度范围内配12Φ14@130钢筋
As=1184mm2＞1156.90mm2）
2、计算基础短边方向.
Ⅱ—Ⅱ截面
1M?(b?bz)2(2l?az)(pjmax?pjmin) Ⅱ481?[(1.6?0.35)2(2?2.4?0.50)(279.99?127.33)]kN?m?70.27kN?m. 48 .
柱下钢筋混凝土独立基础设计说明书
