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3、某缀板式轴压柱由两槽钢2[20a组成,Q235-AF,柱高为7m,两端铰接,在柱中间设有一侧向支撑, iy?7.86cm,f?215Nmm2,试确定其最大承载力设计值(已知单个槽钢[20a的几何特性:

A?28.84cm2,I1?128cm4,?1?35)。

(10分)

解:Ix?2(I1?Aa2)?2?(128?28.84?10.72)?6860cm4(2分)

ix?Ix?A6860?10.9cm(1

2?28.84分)

?x?Lox700??64.2(1ix10.9分)

2?ox??264.22?352?73.1(1分) x??1??y?L0yiy?350?44.5??0x (17.86分)查表?x?0.732(1分)

分)

N??xAf?0.732?2?28.84?102?215?907.8kN (3

3、某缀板式轴压柱由2[28a组成,Q235AF,Lox?Loy?8.4m,外压力N?100kN,验算该柱虚轴稳定承载力。已知:A?40?2?80cm2,

I1?218cm4,Z0?21mm,?1?24, f?215Nmm2。(10分)

解:

Ix?2(I1?Aa2)?2?(218?40?15.92)?20660.8cm4

Ix?A20660.8?16.07cm 80ix?

?x?Lox840252.32?242?57.5查表?x?0.82 ??52.3; ?ox??2x??1?ix16.07N??Af?0.82?8000?215?1410.4kN?1000kN满足要求

共 7 页第 6 页

4、图示焊接工字钢梁,钢材Q345,承受次粱传来的集中荷载,次梁可作为主梁的侧向支撑点,验算该梁的整体稳定。已知:

F?300KN,

A?15840mm2,Wx?4.17?106mm3,Iy?0.51?108mm4,

2????yt1?4320Ah?2350.282'???b??b2?1????,,??1.07??1.0??1.20bbb?4.4h???ywx?f???b??yf?310Nmm2。(10分)

解:

iy?Iy0.51?108??56.74mm(1A15840?4000?70.50(156.74分)

?y?Loyiy分),Mx?Fa?300?4?1200kN?m(2分)

2???t??4320Ah?235y1???b??b2?1???? b???fy?ywx??4.4h???2?235432015840?828?70.5?14???1??=1.20?=3.40?0.6(2???0?264.4?82823570.54.17?10??????分)

?b'?1.07?0.282?0.987(13.40分)

(3分)

Mx1200?106N??291.6N2?f?310'6mmmm2?bWx0.987?4.17?10满足要求

共 7 页第 7 页

5、试验算图示压弯构件弯矩作用平面外的整体稳定性,钢材为Q235,F?900kN,(设计值),偏心距e1?150mm,e2?100mm,

M?tx?0.65?0.352M1,?b?1.07???1.0,跨中翼缘上有一侧向44000235?2yfy支撑,E?206?103Nmm2,f?215Nmm2,对x轴和y轴均为b类截面。(13分)

解:Mx?Fe1?900?0.15?135kN?m(1分)

A?65?1?32?1.2?2?141.8cm2(1Ix?Iy?分)

分)

1?(32?67.43?31?653)?107037cm3(1121?1.2?323?2?6554cm3(112分)

分)

W1x?Ix107037?2??3176.17cm3(1h/267.4iy?IyALoyiy?6554?6.80cm(1141.8400?58.82(16.80分)

?y??分)查表?y?0.814(1分)

58.822235?b?1.07???1.07???0.991(1

4400023544000235?2yfy分)

?tx?0.65?0.35M2112.5?0.65?0.35??0.942(1M1135分)

??txMxN900?1030.942?135?1062????118.4N/mm?yA?bW1x0.814?141.8?1020.991?3176.17?103(3

分)

?f?215Nmm2