lBD?24?(109.610?68.506)?24?19.6?10?6?(10?15)73000? 虚数
?32?320.402?10?0.478?10????lCD?24?(109.610?68.506)?24?19.6?10?6?(?5?15)73000? 虚数
?32?320.427?10?0.478?10????
表2-3 临界档距判别
A lAB?324.39m lAC?159.09m B lBC?虚数 C lCD?虚数 lBD?虚数 lAD?虚数 因为A、B、C栏均存在虚数，所以全线收年平均气温控制。见下图：
由上图可知，全线受D条件控制，控制应力?m?68.506N/mm2。 2.4 导线应力计算（以导线在最高气温下应力的分析计算为例）
Egnl2Egml213.5A?aE(t?t)???C A? B??m? nm232424?mB22当B?0时C?1,B?0时C??1。如果??1有???rcch??ln(???2?1),
?n?B3(2ch?3??C)，ch?e?e?323??3，如果??1有???rccos?，?n?B(2cos?C)，
33?计算各种气象条件下的应力。
（1） 求最高气温时导线应力曲线，此时，年平均气温为已知条件，控制应力为
12
?m?68.506N/mm2，最高气温为待求条件。 当l0?50m时，则：
Egnl273000?(32.77?10?3)2?502A???8165.91
2424Egml2B??m??aE(tn?tm)224?m?68.506?73000?(32.77?10)?50?19.6?10?6?73000?(40?15)?31?0224?68.506?32222
??13.5AB3?C?13.5?8165.9313?1?4.7?1 ，
???rcch??ln(???2?1)?ln(4.7?4.72?1)?2.23
?n?36.97MPa f=0.28m
当l0?100m时，则：
Egnl273000?(32.77?10?3)2?1002A???32663.63
2424B??m?Egml224?m222?aE(tn?tm)
?322?68.506?73000?(32.77?10)?100?6?19.6?10?73000?(40?15)?25.78?0224?68.506??13.5AB3?C?13.5?32663.6325.783?1?26.75?1
???rcch??ln(???2?1)?ln(25.74?25.742?1)?3.979
?n?43.24MPa f=0.95m
当l0?150m时，则
Egnl273000?(32.77?10?3)2?1502A???73488.19
24242 13
B??m?Egml224?m22?aE(tn?tm)
?322?68.506?73000?(32.77?10)?150?19.6?10?6?73000?(40?15)?17.08?0224?68.506??13.5AB3?C?13.5?73488.1917.083?1?200.26?1 ???rcch??arcch199.11?5.993
?n?48.42??a f=1.90m
当l0?200m时，则：
Egnl273000?(32.77?10?3)2?2002A???130654.54
2424B??m?Egml224?m222?aE(tn?tm)
?322?68.506?73000?(32.77?10)?200?6?19.6?10?73000?(40?15)?4.9>0224?68.506??13.5AB3?C?13.5?130654.184.93?1?15028.98?1 ???rccos??arccos(?0.99)?10.311
?n?52.43??a f=3.13m
当l0?250m时，则：
Egnl265000?(31.13?10?3)2?2502A???204147.71
2424Egml2B??m??aE(tn?tm)224?m?68.506?73000?(32.77?10)?250?19.6?10?6?73000?(40?15)??10.76?0224?68.506?32222
??2208.94?1 ???rcch??8.393
?n?55.50??a f=4.61m
14
当l0?300m时，则：
Egnl273000?(32.77?10?3)2?3002A???293972.71
2424Egml2B??m??aE(tn?tm)224?m?68.506?73000?(32.77?10)?300?6?19.6?10?73000?(40?15)??29.90?0224?68.506?32222
??13.5AB3?C?147.41?1
???rcch??5.686 ?n?B3(2ch?3?C)?57.87??a
f=6.37m
当l0?350m时，则：
Egnl273000?(32.77?10?3)2?3502A???400129.52
2424Egml2B??m??aE(tn?tm)224?m?68.506???13.5AB32273000?(32.77?10)?350?6?19.6?10?73000?(40?15)??52.52?0224?68.506?C?36.28?1
?322
???rcch??4.284
?n?B3(2ch?3?C)?59.71??a
f=8.40m
当l0?400m时，则：
Egnl273000?(32.77?10?3)2?4002A???522618.14
24242 15
Egml2B??m??aE(tn?tm)224?m?68.506???13.5AB3273000?(32.77?10)?400?19.6?10?6?73000?(40?15)??78.62?0224?68.506?C?13.52?1
?322
???rccos??3.296
?n?B(2cos?C)?61.15??a 33?f=10.72m
当l0?450m时，则：
Egnl273000?(32.77?10?3)2?4502A???661438.59
2424Egml2B??m??aE(tn?tm)224?m?68.506???13.5AB32273000?(32.77?10)?350?19.6?10?6?73000?(40?15)??108.20?0224?68.506?C?6.05?1
?322
???rcch??2.486
?n?B3(2ch?3?C)?62.29??a
f=13.32m
当l0?500m时，则：
Egnl273000?(32.77?10?3)2?5002A???816590.85
2424Egml2B??m??aE(tn?tm)224?m?68.506?73000?(32.77?10)?350?6?19.6?10?73000?(40?15)??141.26?0224?68.506?32222
16