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Discussion of glass and cladding
Journal of Wind Engineering and lnduslrial Aerodynamics, 41-44 (1992) 2461-2462 Elsevier
2461
Discussion of Glass and Cladding Session chairmen:
J. Minor, University of Missouri, U.S.A. & W. A. Dalgliesh, National Research Council, Canada
Wind Induced External Pressures on a Tall B u i l d i n g with Various Corner Configurations. N. J. Jamieson
Comment by L. S. Coehran I am surveying the procedure used by researchers to define a peak. How did you pick a peak pressure (largest in a given data segment, mean of a number of segments, best linear unbiased estima,~.or method, etc.)?
Author's reply Each sample was divided into 16 sub-samples and the largest negative and positive peak chosen from each. These were then ranked and the peak positive and negative values were calculated from this distribution for a one hour full-scale return period.
Comment by Lakshmg Parameswaran 1. 2.
Is the scale of model going to affect the pressure coefficient of the corner region? How did you account for Reynolds Number effect when building models with curved corners were tested?
Author's reply 1.
It should not, provided the simulation of the boundary layer is appropriate to the particular model scale.
2.
Given the inability of the wind tunnel to match the Reynolds Number of full-scale flow, some wind tunnel operators have reported roughening curved model surfaces to enhance similarity of the flow. For our study, the surface was lightly roughened initially. A few comparative tests were performed with increased roughness. The differences between the two sets & r e s u l t s were within experimental error.
Comment by T. Stathopoulos Were you concerned about Re# effects when you tested the building with rounded corners? Did you find any significant influence of Re# on your results?
Author's reply Given the inability of the wind tunnel to match the Reynolds Number of full-scale flow, some wind tunnel operators have reported roughening curved model surfaces to enhance similarity of the flow. For our study, the surface was lightly roughened initially. A few comparative tests were performed with increased roughness. The differences between the two sets of results were within experimental error.
Post~Breakage Behavior o f Architectural Glazing in Windstorms . C. P. Pantelides, A. D. Horst & J. E. Minor
Comment by Ruben d. Baer What are the economics of using the proposed laminated glass systems? I am not considering post-breakage damage as part of the answer only the cost of the glazing itself.
2462
Author's reply Installed cost of a given nominal thickness of laminated glass is approximately two times the cost of monolithic glass with the same nominal thickness. This approximate relationship is constant for any nominal thickness and glass type (annealed, heat strengthened, fully tempered).
Comment by Arthur Salzman Two particular methods of glazing non-insulated glass panes were presented which seem to retain the glass in the opening, thereby preventing possible damage to nearby objects or persons. Does the use of either of these systems involve special approaches to the actual design of the glass panes themselves?
Author's reply The design of the glass panes themselves would not be affected because a decision was made to use either of the two methods defined. Note, however, the "anchored lite concept" works best with heat strengthened glass and the "sacrificial ply concept" works best with fully tempered glass.
Comment by Arthur Salzman The presentation did not include any mention of insulating glass units. Has any similar work been done, or is any planned for insulating glass units?
Author's reply No work has been done with IG units, nor is any planned. While tests would be required to confirm this observation, an IG unit with a laminated, heat strengthened outer lite, and an 16 unit seal sized to carry 100 percent of the wind load, should perform similarly if anchored in a comparable fashion. An IG unit with an outer lite designed as a "sacrificial ply" should perform similarly.
Nonlinear Dynamic Response o f Window Glass Plates Subjected to Fluctuating Wind Pressures . S. C. Das, C. V. G. Vallabhan & Y. Zhang
Comment by Daryl Boggs I notice that the time signature of applied load begins with a significant non-zero pressure. Were initial conditions (displacement, velocity) assumed arbitrarily (e.g. 0,0) in computing the response? If so, how was it determined what the required time period is until the effects of this assumption decay to insignificance?
Author's reply We assumed the fluctuating wind pressure was suddenly applied to a stationary glass plate (initial displacement and velocity are zero). So, the maximum displacement and the stress response is not the real behavior of the window glass in the first 0.5 seconds which is concluded from the numerical results. This means that the effects of this assumption do not decay to insignificance until 0.5 sec. Generally speaking, after the first 0.5 sec, the response of the maximum displacement and stress can represent the real behavior of the window glass.
2461
Discussion of Glass and Cladding Session chairmen:
J. Minor, University of Missouri, U.S.A. & W. A. Dalgliesh, National Research Council, Canada
Wind Induced External Pressures on a Tall B u i l d i n g with Various Corner Configurations. N. J. Jamieson
Comment by L. S. Coehran I am surveying the procedure used by researchers to define a peak. How did you pick a peak pressure (largest in a given data segment, mean of a number of segments, best linear unbiased estima,~.or method, etc.)?
Author's reply Each sample was divided into 16 sub-samples and the largest negative and positive peak chosen from each. These were then ranked and the peak positive and negative values were calculated from this distribution for a one hour full-scale return period.
Comment by Lakshmg Parameswaran 1. 2.
Is the scale of model going to affect the pressure coefficient of the corner region? How did you account for Reynolds Number effect when building models with curved corners were tested?
Author's reply 1.
It should not, provided the simulation of the boundary layer is appropriate to the particular model scale.
2.
Given the inability of the wind tunnel to match the Reynolds Number of full-scale flow, some wind tunnel operators have reported roughening curved model surfaces to enhance similarity of the flow. For our study, the surface was lightly roughened initially. A few comparative tests were performed with increased roughness. The differences between the two sets & r e s u l t s were within experimental error.
Comment by T. Stathopoulos Were you concerned about Re# effects when you tested the building with rounded corners? Did you find any significant influence of Re# on your results?
Author's reply Given the inability of the wind tunnel to match the Reynolds Number of full-scale flow, some wind tunnel operators have reported roughening curved model surfaces to enhance similarity of the flow. For our study, the surface was lightly roughened initially. A few comparative tests were performed with increased roughness. The differences between the two sets of results were within experimental error.
Post~Breakage Behavior o f Architectural Glazing in Windstorms . C. P. Pantelides, A. D. Horst & J. E. Minor
Comment by Ruben d. Baer What are the economics of using the proposed laminated glass systems? I am not considering post-breakage damage as part of the answer only the cost of the glazing itself.
2462
Author's reply Installed cost of a given nominal thickness of laminated glass is approximately two times the cost of monolithic glass with the same nominal thickness. This approximate relationship is constant for any nominal thickness and glass type (annealed, heat strengthened, fully tempered).
Comment by Arthur Salzman Two particular methods of glazing non-insulated glass panes were presented which seem to retain the glass in the opening, thereby preventing possible damage to nearby objects or persons. Does the use of either of these systems involve special approaches to the actual design of the glass panes themselves?
Author's reply The design of the glass panes themselves would not be affected because a decision was made to use either of the two methods defined. Note, however, the "anchored lite concept" works best with heat strengthened glass and the "sacrificial ply concept" works best with fully tempered glass.
Comment by Arthur Salzman The presentation did not include any mention of insulating glass units. Has any similar work been done, or is any planned for insulating glass units?
Author's reply No work has been done with IG units, nor is any planned. While tests would be required to confirm this observation, an IG unit with a laminated, heat strengthened outer lite, and an 16 unit seal sized to carry 100 percent of the wind load, should perform similarly if anchored in a comparable fashion. An IG unit with an outer lite designed as a "sacrificial ply" should perform similarly.
Nonlinear Dynamic Response o f Window Glass Plates Subjected to Fluctuating Wind Pressures . S. C. Das, C. V. G. Vallabhan & Y. Zhang
Comment by Daryl Boggs I notice that the time signature of applied load begins with a significant non-zero pressure. Were initial conditions (displacement, velocity) assumed arbitrarily (e.g. 0,0) in computing the response? If so, how was it determined what the required time period is until the effects of this assumption decay to insignificance?
Author's reply We assumed the fluctuating wind pressure was suddenly applied to a stationary glass plate (initial displacement and velocity are zero). So, the maximum displacement and the stress response is not the real behavior of the window glass in the first 0.5 seconds which is concluded from the numerical results. This means that the effects of this assumption do not decay to insignificance until 0.5 sec. Generally speaking, after the first 0.5 sec, the response of the maximum displacement and stress can represent the real behavior of the window glass.