大跨度预应力拱板屋架施工质量控制措施

某国家粮库预应力屋盖体系为预应力拱板结构，构件体积大、板壁薄、自重大。为保证施工质量，预制时在两榀屋架预制场地中间留设伸缩缝。上下弦连接板预制成半成品，在屋架整体成型时与上下弦混凝土浇筑连接。分两组由拱板下弦跨中同时向拱板支座浇筑混凝土，然后从拱板支座连续沿拱板上弦向中间合龙，使浇筑荷载相对均衡。

QUALITY CONTROL MEASURE OF ROOF TRUSS OF LARGE SPAN PRESTRESSED ARCH SLAB

Prestress ed arch slab structure is adopted in roof system of a national granary barn of which the elements are of large volume,thin slab and heavy weight.To secure quality,ex pansion joint was remained be-tween two neighbored trusses.Joint slabs at b oth top and bottom chord were pre-cast and then cast-in-situ when the whole r oof truss system were formed.Concrete was poured in separately from mid-span o f arch slab to the supports and then from the supports to the top chord of the a rch chord so as to balance the pouring load.