| 摘要 |
A jib formed in a truss structure liftably supported by an elevating rope attached to the longitudinal intermediate part thereof, comprising an upper chord material extended upward relative to a load action line connecting a lifting point to a supporting pin and a lower chord material extended downward, wherein, where a load applied to the jib from the tip along the lo ad action line when the maximum load is lifted is (P), the vertical width of th e jib at the installation point of the elevating rope is (H), the extended eccentric length of the upper chord material relative to the load action lin e at the installation point of the elevating rope is (Eu) and the extended eccentric length of the lower chord material relative to the load action lin e is (El), and the cross section of the upper chord material is (Au) and the cross section of the lower chord material is (Al), the cross section of the upper chord material (Au) and the cross section of the lower chord material (Al) are determined according to the extended eccentric length of the upper chord material (Eu) and the extended eccentric length of the lower chord material (El), respectively, to meet the requirement of P x El/H.Au > P x Eu/H.Al so that the upper part of the jib is warped toward a crane main body side when the maximum load islifted.
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