Wind loads for designing the main wind-force resisting systems of cylindrical free-standing canopy roofs

Yasushi Uematsu,

Roma Yamamura

Abstrakt

Wind loads on cylindrical free-standing canopy roofs were investigated in a wind tunnel. First, the overall aerodynamic forces and moments were measured using a force balance. The distributions of net wind pressures provided by the difference between wind pressures on the top and bottom surfaces of the roof were then measured along two representative arc lines. Based on the results, the net wind-pressure coefficients for designing such roofs are proposed as a function of the rise-to-span ratio for two representative wind directions: one perpendicular to the eaves, the other inclined at an angle of 45° to the eaves. The roof is divided into three zones and constant net wind-pressure coefficients are specified for these zones. Two load cases providing the maximum tension and compression in the columns supporting the roof are considered as the most important load effect for discussing the design wind loads.

Keywords: cylindrical free-standing canopy roof, wind load, main wind-force resisting system, wind tunnel experiment, dynamic load effect

Obciążenia wiatrem przy projektowaniu głównych systemów odpornych na siłę wiatru cylindrycznych dachów wolnostojących

Streszczenie

Obciążenia wiatrem na cylindrycznych dachach wolnostojących zadaszenia zbadano w tunelu aerodynamicznym. Ogólne siły i momenty aerodynamiczne zmierzono za pomocą równowagi sił. Następnie zmierzono rozkłady ciśnień wiatru netto, które wynikają z różnicy ciśnień wiatru na górnej i dolnej powierzchni dachu, wzdłuż dwóch reprezentatywnych linii łuku. Na podstawie wyników zaproponowano współczynniki ciśnienia wiatru netto do projektowania takich dachów jako funkcję stosunku wzrostu do rozpiętości dla dwóch reprezentatywnych kierunków wiatru: jednego prostopadłego do okapu, drugiego nachylonego pod kątem 45° do okap. Dach podzielony jest na trzy strefy i dla tych stref określono stałe współczynniki ciśnienia wiatru netto. Dwa przypadki obciążeń zapewniające maksymalne naprężenie i ściskanie kolumn podtrzymujących dach są uważane za najważniejszy efekt obciążenia do omawiania obliczeniowych obciążeń wiatrem.

Słowa kluczowe: cylindryczny dach wolnostojący, obciążenie wiatrem, główny system oporu wiatru, eksperyment w tunelu aerodynamicznym, efekt obciążenia dynamicznego

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