Influence of various types of node connectors on the buckling loads of grid shells. Evolution and Trends in Design, Analysis and Construction of Shell ans Spatial Structures, IASS Symposium, 426 – 427, Valencia, Spain, 28. Sept.r – 2. Oct. 2009. [PUMA: 2009 buckling connection connector engineering from:petraheim grid hwang influence itke knippers load node park shell types various]