General Information
Figure 1 shows a steel canopy roof.
![Steel canopy roof](canopy-roofs/structure-4/1-canopy-roof.jpg)
Canopy Roof Failure
Figure 2 shows the canopy roof of figure 1 and a next to failed steel canopy roof.
![A steel canopy roof and a failed steel canopy roof.](canopy-roofs/structure-4/2-canopy-roofs.jpg)
Both canopy roofs have the same cantilever truss type and external roof geometry. Figure 3 shows the failed canopy roof viewed from below.
![Back sector of a failed steel canopy roof.](canopy-roofs/structure-4/3-failed-canopy.jpg)
The connection between the canopy roof and the reinforced concrete structure of the building consisted of plates and anchor bolts. The upper plates are connected to the purlin; the bottom plates, to the longitudinal beam. The upper and bottom plates are different in geometry, connection position, and number. Figure 4 shows a schematic front view of the canopy roof to building connection.
![Schematic drawing of a connection between canopy roof and building.](canopy-roofs/structure-4/4-front-view.jpg)
Each upper plate connects two anchor bolts, while each bottom plate connects a single anchor bolt. Figure 5 shows an upper and a bottom plate.
Upper plate | Bottom plate |
![Steel plates with anchor bolts of a failed canopy roof.](canopy-roofs/structure-4/5-plates.jpg)