风荷载计算书
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七、水平荷载(风荷载)计算
1、设计资料
基本风压:
2
/35.0m KN =ωο
,地面粗糙度类别为C 类。房屋高度H=21.9m 。 2、荷载计算
风荷载近似按阶梯形分布,首先应将其简化为作用在框架节点上的节点荷载。
作用在屋面梁和楼面梁节点处的集中风荷载标准值:
0k z s z ωβμμω=
式中 K W ——风荷载标准值(KN/m 2);
z β——高度z 处的风振系数,结构高度H=21.9m <30m ,故取βZ
=1.0;
s μ——风荷载体型系数,对于矩形截面s μ=1.3; z μ——风压高度变化系数(地面粗糙度类别为C 类);
0w ——基本风压(KN/m 2);
风压高度变化系数z μ可查荷载规范取得。将风荷载换算成作用与框架每层节点上的集中荷载,计算过程如下表所示。表中z 为框架节点至室外地面的高度,A 为一榀框架各层节点的受风面积
表4.1
层次 z β s μ
0w
Z μ
k z s z ωβμμω=
A(m 2) P K (kN)=
A ×k ω 6 1.0 1.3 0.35 1.00 0.46 5.85 2.69 5 1.0 1.3 0.35 0.84 0.38 14.63 5.56 4 1.0 1.3 0.35 0.84 0.38 16.88 6.41 3 1.0 1.3 0.35 0.74 0.34 16.2 5.51 2 1.0 1.3 0.35 0.74 0.34 16.2 5.51 1
1.0
1.3
0.35 0.74
0.34
24.3
8.26
2
1
3.245.4)2/6.36.3(m A =?+= 2
2
2.165.46.3m
A =?= 2
3
2.165.46.3m
A =?=
2
4
88.165.4)2/6.32/9.3(m A =?+=
2
5
63.145.4)2/6.22/9.3(m A =?+=
26
85.55.4)2/6.2(m A =?= 故风荷载下的计算简图为:
图4.13 风荷载计算简图 3. 风荷载下的横向框架内力计算—反弯点法 3.1各柱剪力按刚度分配法计算公式为:
1
ij
ij pi s
ij
j D V V D
==
∑
式中,pi V ——为该平面框架i 层总剪力; ij V ——为i 层第j 根柱分配到的剪力;
ij D ——为i 层第j 根柱的抗侧刚度; 1s
ij j D =∑——为i 层s 根柱的抗侧刚度之和。
3.2各层柱的剪力分配和柱端弯距的计算
第六层: V=2.69KN
G
柱
:
43.176
.222
96.3=??=
K
04.26
.212
76.243.1243.12
=??+=
D KN/M H 柱:59.480
.322
)5.1396.3(=??+=
K
70.46
.212
80.359.4259.42
=??+=
D KN/M J 柱:59.480
.322
)5.1396.3(=??+=
K
70.46
.212
80.359.4259.42
=??+=
D KN/M L 柱:43.176.22296.3=??=
K 04.26.212
76.243.1243.12
=??+=D KN/M
48.1370.470.404.204.2=+++=∑D KN/M
G 柱剪力:KN V 41.069.248
.1304
.26=?=
H 柱剪力:KN V 94.069.248
.1370
.46=?=
J 柱剪力:KN V 94.069.248
.1370
.46=?=
L 柱剪力:KN V 41.069.248
.1304
.26=?=
第五层: V=2.69+5.56=8.25KN
G
柱:14.285
.122
96.3=??=
K
75.09
.312
85.114.2214.22=??+=
D KN/M
H
柱:87.654
.222
)5.1396.3(=??+=
K
55.19
.312
54.287.6287.62=??+=
D KN/M
J
柱:87.654
.222
)5.1396.3(=??+=
K
55.19.312
54.287.6287.62=??+=
D KN/M
L 柱:14.285.12296.3=??=
K 75.09
.312
85.114.2214.22=??+=D KN/M ∑=+++=6.455.155.175.075.0D KN/M
G 柱剪力:KN V 35.125.86.475
.05=?=
H 柱剪力:KN V 78.225.86.455
.15=?= J 柱剪力:KN V 78.225.86.455
.15=?= L 柱剪力:KN V 35.125.86
.475
.05=?= 第四层: V=2.69+5.56+6.41=14.66KN
G
柱:98.10
.222
96.3=??=
K
92.06
.312
0.298.1298.12=??+=
D KN/M
H
柱:35.675
.222
)5.1396.3(=??+=
K
94.16
.312
75.235.6235.62=??+=
D KN/M
J
柱:35.675
.222
)5.1396.3(=??+=
K
94.16.312
75.235.6235.62=??+=
D KN/M
L 柱:98.10.22296.3=??=
K 92.06
.312
0.298.1298.12=??+=D KN/M 72.594.194.192.092.0=+++=∑D KN/M
G 柱剪力:KN V 36.266.1472.592
.04=?=
H 柱剪力:KN V 90.466.1472.594
.14=?=
J 柱剪力:KN V 90.466.1472.594
.14=?=
L 柱剪力:KN V 36.266.1472
.592
.04=?=
第三层: V=2.69+5.56+6.41+5.51=20.17KN
G 柱剪力:KN V 24.317.2072.592
.03=?=
H 柱剪力:KN V 84.617.2072.594
.13=?=
J 柱剪力:KN V 84.617.2072.594
.13=?=
L 柱剪力:KN V 24.317.2072
.592
.03=?=
第二层: V=2.69+5.56+6.41+5.51+5.51=25.68KN
G 柱剪力:KN V 13.468.2572.592
.02=?=
H 柱剪力:KN V 71.868.2572.594
.12=?=
J 柱剪力:KN V 71.868.2572.594
.12=?=
L 柱剪力:KN V 13.468.2572
.592
.02=?=
第一层: V=2.69+5.56+6.41+5.51+5.51+8.26=33.94KN
G
柱:29.273
.196
.3==
K 04.16
.312
73.129.22)29.25.0(2
=??++=
D KN/M H
柱:34.738
.25
.1396.3=+=
K
85.16
.312
38.234.72)34.75.0(2=??++=
D KN/M
J
柱:34.738
.25
.1396.3=+=
K
85.16.312
38.234.72)34.75.0(2=??++=
D KN/M
L 柱:29.273.196.3==
K 04.16.312
73.129.22)29.25.0(2
=??++=D KN/M 78.585.185.104.104.1=+++=∑D KN/M
G 柱剪力:KN V 12.694.3378.504
.11=?=
H 柱剪力:KN V 86.1094.3378.585
.11=?=
J 柱剪力:KN V 86.1094.3378.585
.11=?=
L 柱剪力:KN V 12.694.3378
.504
.11=?=
3.3水平风荷载作用下楼层层间位移验算
表4.2 层次 ()i F KN ()i V KN (/)i
D KN m ∑
()i u mm ? ()i h mm /e i i u h θ=?
6 2.69 2.69 134800 0.012 2600 1/216666 5 5.56 8.25 46000 0.073 3900 1/53424 4 6.41 14.66 57200 0.170 3600 1/21176 3 5.51 20.1
7 57200
0.267 3600 1/13483 2 5.51 25.68 57200 0.363 3600 1/9917 1
8.26
33.94
57800
0.502
4600
1/9163
最大层间弹性位移角e θ=1/9163<1/550,满足规范要求。
3.4 风荷载框架内力计算
近似取上部各层柱子的反弯点在柱子中点,因为底层柱的底端为固定端,底
层反弯点设在
1
23
h 处。 根据各柱分配到的剪力及反弯点位置yh 计算第i 层第j 个柱端弯矩 上端弯矩: M t ij =V ij h (1-y ) 下端弯矩: M b ij = V ij hy 各柱柱端弯距见下表:(单位:KN ·m ) 表4.3
层次
端点
G 柱 H 柱 J 柱 L 柱 6
上
0.41×1.3 =0.53 0.94×1.3 =1.22 0.94×1.3 =1.22 0.41×1.3 =0.53 下
0.41×1.3 =0.53 0.94×1.3 =1.22 0.94×1.3 =1.22 0.41×1.3 =0.53 5
上
1.35×1.95 =
2.63 2.78×1.95 =5.42 2.78×1.95 =5.42 1.35×1.95
=2.63 下
1.35×1.95 =
2.63 2.78×1.95 =5.42 2.78×1.95 =5.42 1.35×1.95 =2.63 4
上
2.36×1.8 =4.25 4.90×1.8 =8.82 4.90×1.8 =8.82 2.36×1.8 =4.25 下
2.36×1.8 =4.25 4.90×1.8 =8.82 4.90×1.8 =8.82 2.36×1.8 =4.25 3
上
3.24×1.8 =5.83 6.84×1.8 =12.31 6.84×1.8 =12.31 3.24×1.8 =5.83 下
3.24×1.8 =5.83 6.84×1.8 =12.31 6.84×1.8 =12.31 3.24×1.8 =5.83 2
上
4.13×1.8 =7.43 8.71×1.8 =1
5.68 8.71×1.8 =15.68 4.13×1.8 =7.43 下
4.13×1.8 =7.43 8.71×1.8 =1
5.68 8.71×1.8 =15.68 4.13×1.8 =7.43 1
上
6.12×1.2
10.86×1.2
10.86×1.2
6.12×1.2
=7.34 =13.03 =13.03 =7.34
下6.12×2.4
=14.69
10.86×2.4
=26.06
10.86×2.4
=26.06
6.12×2.4
=14.69
当计算出了框架在水平力作用下的柱端弯矩值后,求梁端弯矩时,由柱端弯矩,并根据节点平衡来求。
对于边跨梁端弯矩:M
bi =M t
ij
+M b
j
i,1+
对于中跨,由于梁的端弯矩与梁底线刚度成正比,因此,
M l
bi =(M t
ij
+M b
j
i,1+
)
r
b
l
b
l
b
i
i
i
+
M r
bi
=(M t
ij
+M b
j
i,1+
)
r
b
l
b
r
b
i
i
i
+
t
ij
M
l
b
i r
b
i
l
bi
M r
bi
M
b
i+1j
M
,
表4.4 层次
GH 跨
HJ 跨
JL 跨
左端 右端
左端 右端 左端
右端 6
0.53 28
.05.1396.396.322.1=+?
1.22- 0.28= 0.94 1.22- 0.28= 0.94 28
.05.1396.396.322.1=+?
0.53
5
0.53+ 2.63 =3.16 51.15.1396.396
.3)42.522.1(=+?+
1.22+ 5.42- 1.51= 5.13 1.22+ 5.42- 1.51= 5.13 51.15.1396.396
.3)42.522.1(=+?+
0.53+ 2.63 =3.16 4
2.63+ 4.25 =6.88 23
.35.1396.396
.3)82.842.5(=+?+
5.42+ 8.82- 3.23= 11.01 5.42+ 8.82- 3.23= 11.01 23
.35.1396.396
.3)82.842.5(=+?+
2.63+ 4.25 =6.88 3 4.25+
5.83 =10.08 79.45
.1396.396.3)31.1282.8(=+?
+
8.82+ 12.31- 4.79= 16.34 8.82+ 12.31- 4.79= 16.34 79
.45.1396.396
.3)31.1282.8(=+?+
4.25+
5.83 =10.08 2 5.83+
7.43 =13.26 35.65
.1396.396.3)68.1531.12(=+?
+
12.31+ 15.68- 6.35= 21.64 12.31+ 15.68- 6.35= 21.64 35
.65.1396.396
.3)68.1531.12(=+?+
5.83+ 7.43 =13.26 1 7.43+
7.34 =14.77 51
.65
.1396.396
.3)03.1368.15(=+?
+
15.68+ 13.03- 6.51= 22.2
15.68+ 13.03- 6.51= 22.2
51
.65.1396.396
.3)03.1368.15(=+?+
7.43+ 7.34 =14.77
图4.14 左风荷载弯矩图(单位:KN·m)
剪力计算表 4.5
层次
梁柱
GH跨HJ跨JL跨G H J L
6 (0.53+
0.28)
/7.8=
0.10
(0.94+0.
94)/2.4=
0.78
(0.53+
0.28)
/7.8= 0.10
0.53×
2/2.6
=0.41
1.22×
2/2.6
=0.94
1.22×
2/2.6
=0.94
0.53×
2/2.6
=0.41
5 (3.16+
1.51)
/7.8=
0.60
(5.13+5.
13)/2.4=
4.28
(3.16+
1.51)
/7.8= 0.60
2.63×
2/3.9
=1.35
5.42×
2/3.9
=2.78
5.42×
2/3.9
=2.78
2.63×
2/3.9
=1.35
4 (6.88+
3.23)
/7.8=
1.30
(11.01+1
1.01)
/2.4=9.16
(6.88+3.
23)/7.8=
1.30
4.25×
2/3.6
=2.36
8.82×
2/3.6
=4.90
8.82×
2/3.6
=4.90
4.25×
2/3.6
=2.36
3 (10.08
+4.79)
/7.8=
1.91
(16.34+1
6.34)
/2.4=13.6
2
(10.08+4
.79)/7.8=
1.91
5.83×
2/3.6
=3.24
12.31×
2/3.6
=6.84
12.31×
2/3.6
=6.84
5.83×
2/3.6
=3.24
2 (13.26
+6.35)
/7.8=
2.51
(21.64+2
1.64)
/2.4=18.0
3
(13.26+6
.35)/7.8=
2.51
7.43×
2/3.6
=4.13
15.68×
2/3.6
=8.71
15.68×
2/3.6
=8.71
7.43×
2/3.6
=4.13
1 (14.77
+6.51)
/7.8=
2.73
(22.20+2
2.20)
/2.4=18.5
(14.77+6
.51)/7.8=
2.73
(7.34+
14.69)
/3.6
=6.12
(13.03
+26.06)
/3.6
=10.86
(13.03+
26.06)
/3.6
=10.86
(7.34+14
.69)/3.6
=6.12
图4.15 左风荷载剪力图(单位:KN)柱的轴力以受压为负,受拉为正:表4.6
层次
柱
G H J L
6 0.10 0.10-0.78=-0.68 0.78-0.10=0.68 0.10
5 0.10+0.60=0.70 -0.68+0.60-4.28
=-4.36
0.68+4.28-0.60=4
.36
0.10+0.60=0.70
4 0.70+1.30=2.00 -4.36+1.30-9.16
=-12.22
4.36+9.16-1.30
=12.22
0.70+1.30=2.00
3 2.00+1.91=3.91 -12.22+1.91-13.
62=-23.93
12.22+13.62-1.91
=23.93
2.00+1.91=
3.91
2 3.91+2.51=6.42 -23.93+2.51-18.
03
=-39.45
23.93+18.03-2.51
=39.45
3.91+2.51=6.42
1 6.42+2.73=9.15 -39.45+2.73-18.
50=-55.22
39.45+18.50-2.73
=55.22
6.42+2.73=9.15
图4.16 左风荷载轴力图(单位:KNm
注:右风荷载作用下的内力与左风荷载下的内力大小相等方向相反