Behavior of Harp Bracings in Rigid Frame Metallic Bays

摘要

Simple two-dimensional frames are normally used when building bays. These frames are placed in series and held longitudinally with bracings. These two directions, transversal and longitudinal, are independent of each other. Thus, the transverse frame bears loads in its plane with no help from the longitudinal bracings. In the case of transverse rigid frames, with the typology described, the columns act as bending brackets, requiring large-size columns and large foundations. Against the traditional typology, an alternative can be the usage of special on-roof bracings called "harp bracings." With these harp bracings, the loads received by the columns are partially transmitted to the endwall frame. In this way, the columns tend to behave as encastered-supported elements, which require smaller section size and foundations. This paper presents a comparative study between rigid frames, solved with traditional bracings, and harp bracings. Spans from 10 to 35 m are considered, as well as bay lengths from 20 to 50 m. The contrast between these bracing systems is made using the budgets for the whole bay frame, including metallic frame and foundations. The results show the advantages of the harp bracings versus the traditional bracing.