Dynamic and Static Stability and Safety Limitations of Lift Slab Structures

理论证据和实际事故都指出，在一定的荷载条件下，升降板结构处于静、动力失稳的阈值。结构的不稳定性是由高水平的厚板堆积造成的，而结构不能横向支撑，因为支撑会抑制提升过程。在施工阶段或在横向荷载作用下，这种失稳情况是非常不可取的。该项目对结构保持静态和动态稳定的限制进行了调查。该项目还将包括对所使用的安全预防措施的方式和手段进行研究，并提出必要的改进建议。将进行理论研究，以改进提升板结构的设计、抗震性能，并建议如何加强现有的提升板结构以抵御未来可能发生的地震。这种改进应有助于避免类似1988年亚美尼亚地震期间发生的悲剧。通过计算机分析，研究了停放板的堆垛方案、各方案与结构几何的安全关系、保证安全吊装过程的安全动荷载和动荷载频率的极限、停放板与立柱的安全临时连接。＊＊＊

9504541 Masih Theoretical evidence as well as practical accidents have pointed out that under certain loading conditions the lift-slab structures are at the threshold static and dynamic instability. The instability of the structure is created by stacking the heavy mass of several slabs at high levels, while the structure cannot be braced laterally, since the bracing will inhibit the lifting process. During construction stage or under lateral loads, such an instability situation becomes highly undesirable. This project undertakes an investigation to the limitations within which the structure remains statically and dynamically stable. The project would also include a study of the ways and means of the safety precautions used and necessary recommendations to improve them. Theoretical studies to improve the design of lift-slab structure, performance against earthquake forces, and to recommend ways to strengthen the existing lift-slab structures to withstand possible future earthquakes will be conducted. Such improvement should help to avoid tragedies like those which happened in Armenia during the 1988 earthquake. Computer analysis will be made to study limitations as: the stacking schemes of the parked slabs, the safe relationship of those schemes with the geometry of the structure, the limits of safe dynamic load and its frequency to maintain safe lifting process, and the safe temporary connection of the parked slab to the columns. ***