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A series of five full-scale, nearly conventional, curtain wall specimens was tested in the UNC Charlotte Structures Laboratory. Specimens were subjected to quasi-static, uniform, out-of-plane loading to failure under displacement control. The tests were performed to obtain complete resistance curves, including the nonlinear behavior of the specimens up to ‘ultimate failure’. Ultimate failure was defined as mullion fracture or significant breach of the curtain wall system when viewed as the protective barrier between building occupants and the external blast load. Representative load-deflection and loadstrain resistance curves are presented. The energy absorbed by the curtain wall system up to three different limit states – first cracking of glass, first yield of mullions, and fracture/breach of the system (ultimate failure) – and maximum mullion end rotations are computed from the experimental results. Ultimate energy absorption capacity – the recoverable linear strain energy plus the nonlinear energy due to formation of damage mechanisms – and maximum mullion end rotations are essential for reliable and economical design of blast resistant curtain walls. To this end, a simplified methodology is presented for analytically approximating curtain wall resistance functions that can be input to an energy expression that models nonlinear structural dynamic behavior due to an ‘impulsive’ loading. The blast resistance of a curtain wall can then be approximated using this procedure. It is shown that a nearly conventional curtain wall, a conventional system with two modifi cations – use of laminated glass lites that are structurally glazed (wet-glazed) to a conventional framing system with structural silicone sealant – had nearly 14 times the ultimate energy absorption capacity and nearly four times the blast resistance as the fully conventional system.
Glass curtain wall, blast resistance, nonlinear SDOF design expression, static destructive tests
[1] Weggel, D.C. & Zapata, B.J., Laminated glass curtain walls and laminated glass lites subjected to low-level blast loading. Journal of Structural Engineering, 134(3), pp. 466–477, 2008. doi: http://dx.doi.org/10.1061/(ASCE)0733-9445(2008)134:3(466)
[2] Weggel, D.C., Zapata, B.J. & Kiefer, M.J., Properties and dynamic behavior of glass curtain walls with split screw spline mullions. Journal of Structural Engineering, 133(10), pp. 1415–1425, 2007. doi: http://dx.doi.org/10.1061/(ASCE)0733-9445(2007) 133:10(1415)
[3] Biggs, J.M., Introduction to Structural Dynamics, McGraw-Hill, Inc., 1964.
[4] Beason, W.L. & Morgan, J.R., Glass failure prediction model. Journal of Structural Engineering, 110(2), pp. 197–222, 1984. doi: http://dx.doi.org/10.1061/(ASCE)0733-9445(1984)110:2(197)
[5] Vallabhan, C.V.G., Interactive analysis of nonlinear glass plates. Journal of Structural Engineering, 102(2), pp. 489–502, 1983. doi: http://dx.doi.org/10.1061/(ASCE)0733-9445(1983)109:2(489)
[6] ASTM, Standard Practice for Determining Load Resistance of Glass in Buildings, E1300-09a, West Conshohocken, PA, 2009.
[7] Behr, R.A., Kremer, P.A., Dharani, L.R., Ji, F.S. & Kaiser, N.D., Dynamic strains in architectural glass subjected to low velocity impacts from small projectiles. Journal of Materials Science, 34, pp. 5749–5756, 1999. doi: http://dx.doi.org/10.1023/A:1004702100357
[8] Behr, R.A., Minor, J.E. & Linden, M.P., Load duration and interlayer thickness effect on laminated glass. Journal of Structural Engineering, 112(6), pp. 1441–1453, 1986. doi: http://dx.doi.org/10.1061/(ASCE)0733-9445(1986)112:6(1441)
[9] Behr, R.A., Minor, J.E. & Norville, H.S., Structural behavior of architectural laminated glass. Journal of Structural Engineering, 119(1), pp. 202–223, 1993. doi: http://dx.doi.org/10.1061/(ASCE)0733-9445(1993)119:1(202)
[10] Makovicka, D. & Lexa, P., Dynamic response of window glass plates under explosion overpressure. Proc., 2nd Int. Conf. on Struct. Under Shock and Impact II, Computational Mechanics Publications: Southampton, England, pp. 380–392, 1992.
[11] Norville, H.S., King, K.W. & Swofford, J.L., Behavior and strength of laminated glass. Journal of Engineering Mechanics, 124(1), pp. 46–53, 1998. doi: http://dx.doi.org/10.1061/(ASCE)0733-9399(1998)124:1(46)
[12] Vallabhan, C.V.G., Asik, M.Z. & Kandil, K., Analysis of structural glazing systems. Computers & Structures, 65(2), pp. 231–239, 1997. doi: http://dx.doi.org/10.1016/S0045-7949(96)00284-2
[13] Norville, H.S. & Conrath, E.J., Blast-resistant glazing design. Journal of Architectural Engineering, 12(3), pp. 129–136, 2006. doi: http://dx.doi.org/10.1061/(ASCE)1076-0431(2006)12:3(129)
[14] ASTM, Specifying an Equivalent 3-Second Duration Design Loading for Blast Resistant Glazing Fabricated with Laminated Glass, F2248-09, West Conshohocken, PA, 2003.
[15] AAMA, Structural Performance: Poured and Debridged Framing Systems, American Architectural Manufacturers Association: Palatine, IL, 1990.
[16] Goodno, B.J., Glass curtain wall elements: properties and behavior. Journal of. Structural Division, 105(6), pp. 1121–1136, 1979.
[17] Hautekeer, J.P., Monga, F., Giesecke, A. & O’Brien, B., The use of silicone sealents in protective glazing applications. Glass processing days, Tampere, Finland, pp. 298–302, 2001.
[18] Vallabhan, C.V.G., Chou, G.D. & Minor, J.E., Seal forces in structural glazing systems. Journal of Structural Engineering, 116(4), pp. 1080–1089, 1990. doi: http://dx.doi.org/10.1061/(ASCE)0733-9445(1990)116:4(1080)
[19] Zarghamee, M.S., Schwartz, T.A. & Gladstone, M., Seismic behavior of structural silicone glazing. ASTM Special Tech. Publ., (1286), pp. 46–59, 1996.
[20] Behr, R.A., Belarbi, A. & Culp, J.H., Dynamic racking tests of curtain wall in-plane and out-of-plane motions. Earthquake Engineering Structural Dynamics, 24(1), pp. 1–14, 1995. doi: http://dx.doi.org/10.1002/eqe.4290240102
[21] Memari, A.M., Behr, R.A. & Kremer, P.A., Dynamic racking crescendo tests on architectural glass fi tted with anchored pet fi lm. Journal of Architectural Engineering, 10(1), pp. 5–14, 2004. doi: http://dx.doi.org/10.1061/(ASCE)1076-0431(2004)10:1(5)
[22] Memari, A.M., Chen, X., Kremer, P.A. & Behr, R.A., Seismic performance of two-side structural silicone glazing systems. Journal of ASTM International, 3(10), pp. 1–10, 2006.
[23] Pantelides, C.P. & Behr, R.A., Dynamic in-plane racking tests of curtain wall glass elements. Earthquake Engineering Structural Dynamics, 23(2), pp. 211–228, 1994. doi: http://dx.doi.org/10.1002/eqe.4290230208
[24] Craig, J.I. & Goodno, B.J., Response measurements for glass cladding panels. Journal of Structural Division, 107(11), pp. 2199–2214, 1981.
[25] Goodno, B.J. & Craig, J.I., Response studies of glass cladding panels. Proc., Int. Symp. on Bhvr. of Bldg. Sys. and Bldg. Comp., Nashville, TN, pp. 137–158, 1979.
[26] Clift, C.D., Curtain wall designs for wind and blast: three case studies. Journal of Architectural Engineering, 12(3), pp. 150–155, 2006. doi: http://dx.doi.org/10.1061/(ASCE)1076-0431(2006)12:3(150)
[27] Dawson, H. & Smilowitz, R., Inelastic dynamic response of curtainwall systems to blast loading. Journal of ASTM International, 4(5), pp. 1–5, 2007.
[28] U.S. General Services Administration, GSA Test Protocol GSA-TS01-2003 US General Services Administration Standard Test Method for Glazing and Window Systems Subject to Dynamic Overpressure Loadings, US General Services Administration: Washington, D.C., 2003.
[29] ARA, WINGARD-MP (Multi-Pane Edition) User Guide, Applied Research Associates, 2010.
[30] Cussen, R. & Van Eepoel, P., Inelastic dynamic fi nite-element design of glazed façade systems for blast loading. Crossing Borders: Structures Congress 2008, Vancouver, Canada, pp. 1–11, 2008.
[31] Edel, M.T. & Kumar, D., Blast design approach comparisons for curtain wall. Proc., 2010 Struct. Cong., Orlando, FL, pp. 2076–2089, 2010. doi: http://dx.doi.org/10.1061/41130(369)188
[32] ASTM, Standard Test Methods for Tension Testing Wrought and Cast Aluminum- and Magnesium-Alloy Products, B557-06, West Conshohocken, PA, 2006.
[33] Norville, H.S. & Conrath, E.J., Considerations for blast-resistant glazing design. Journal of Architectural Engineering, 7(3), pp. 80–86, 2001. doi: http://dx.doi.org/10.1061/(ASCE)1076-0431(2001)7:3(80)