| 摘要 |
<p>The steel beam is preloaded by bending or stretching, or by combined bending and stretching so that, when invested with concrete and subjected to its working load it will not subject the concrete to a tensile force liable to cause cracking. To ensure that the beam deflection does not exceed the elastic limit, the beam is subjected to the loading it would receive in service. The load is relieved and, if there is a residual deflection, the loading is repeated until no residual deflection occurs after relieving the load. The beam is then invested with concrete.</p> |
