{"title":"Instability of Ties in Compression","authors":"T. Cornelius","volume":76,"journal":"International Journal of Civil and Environmental Engineering","pagesStart":303,"pagesEnd":308,"ISSN":"1307-6892","URL":"https:\/\/publications.waset.org\/pdf\/14082","abstract":"
Masonry cavity walls are loaded by wind pressure and vertical load from upper floors. These loads results in bending moments and compression forces in the ties connecting the outer and the inner wall in a cavity wall. Large cavity walls are furthermore loaded by differential movements from the temperature gradient between the outer and the inner wall, which results in critical increase of the bending moments in the ties. Since the ties are loaded by combined compression and moment forces, the loadbearing capacity is derived from instability equilibrium equations. Most of them are iterative, since exact instability solutions are complex to derive, not to mention the extra complexity introducing dimensional instability from the temperature gradients. Using an inverse variable substitution and comparing an exact theory with an analytical instability solution a method to design tie-connectors in cavity walls was developed. The method takes into account constraint conditions limiting the free length of the wall tie, and the instability in case of pure compression which gives an optimal load bearing capacity. The model is illustrated with examples from praxis.<\/p>\r\n","references":"[1] H. W. H. West, H. R. Hodkinson and R. C. de Vekey, \"The lateral\r\nresistance of cavity walls with different types of wall-ties,\" the british\r\nceramic research association, Oct. 1979\r\n[2] H.H. Knuttson, \"Tr\u251c\u00d1dbindere til forankring af skalmure og hule mure\",\r\nSBI anvisning 157, Danish Building Research Institute, Aalborg\r\nUniversity, Denmark, 1989,\r\n[3] A. Ostenfeld, \"Exzentrische und zentrische KnickfestigkeiC, Zeitschrift\r\ndes Vereines deutscher Ingenieure, Vol. 94,1898, p. 1462\r\n[4] V. Straka, \"Composite masonry wall ties,\" CMHC publisher, Canada,\r\nNov. 2001.\r\n[5] M. A. Postma and E. F. P. Burnett, \"Performance of Helifix ties in\r\nconcrete block,\" University of Waterloo ,Waterloo, Canada, 1990.\r\n[6] A. M. Memari, E. F. P. Burnett and B. M. Kozy, \"Seismic response of a\r\nnew type of masonry tie used in brick veneer walls,\" Construction and\r\nBuilding Materials 16, Elsevier, May. 2002\r\n[7] S. Palkowski, \"Buckling of parabolic arches with hangers and tie,\"\r\nEngineering structures 44, Elsevier, 2012.","publisher":"World Academy of Science, Engineering and Technology","index":"Open Science Index 76, 2013"}