HomeMy WebLinkAboutB14-0274_windscreen clamps report_1406913060.pdf 30 OCT 2008
Architectural Railing Division
C.R.Laurence Co., Inc.
2503 E Vernon Ave.
Los Angeles, CA 90058
(T) 800.421.6144
(F) 800.587.7501
www.crlaurence.com
SUBJ: FRAMELESS WINDSCREEN CLAMPS
The frameless windscreen is intended for use in locations where fall protection is not
required. The maximum panel length should not exceed 5 feet. Allowable loading for
given panel height shall be in accordance with table 1. The clamps should be installed at
1/4 the panel length from each end. The windscreen is designed for the following loading
conditions:
50 plf load along glass at now higher than 48" above finish floor horizontal or
wind load as shown in attached calculations for specified panel size.
The frameless windscreen clamps may be used for fall protection in single family
residential occupancies when limited to 42" height,panel length of 5 feet and installed
with a top rail capable of spanning 10 feet. For these conditions the system will support
the above stated loads or a 200 lb concentrated load on the top rail,vertically or
horizontally with a factor of safety of 4.0 against glass failure.
For these conditions the railing meets all requirements of the 2,003 and 2006
International Building Code and 2007 California Building Code. Stainless steel
components are evaluated in accordance with SEI ASCE 8-02,Specification for the
Design of Cold-Formed Stainless Steel Structural Members. The glass components are
evaluated in accordance with GANA Glazing Manual, Tempered Glass Engineering
Standards Manual and Laminated Glazing Reference Manual.
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If you have any questions please call me at 253-858-0855. ck Q��
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Edward Robison,P.E. a , 0 1T
W No. C 65883 Z m
Attachments: _ ,
Calculations—7 pages I � --
Windscreen Layout- 1 page `97 Cl V�\- QIP
OF CAL�F6
EXP 12/31/2009
EDWARD C.ROBISON,PE
10012 Creviston Dr NW
Gig Harbor,WA 98329
253-858-0855/Fax 253-858-0856 elrobison@narrows.com
CRL Frameless Windscreen Clamps Page 2 of 8
Three Piece Core Mount Frameless Windscreen Clamp
1/2" Fully tempered glass panels
supported by stainless steel posts
anchored in concrete.
� .11
I I IIIA
I I itis
Three Piece Post Option: I I
Post is attached to 1/2"rod set into
concrete and grouted to base of side bars.
1-15/16'
Gasket for 3/6'or 1/2' (50 mm)
Determine strength of anchorage into concrete: (10 or 12 mm)Glass 1 t
• I 1 N
Moment is resisted be a combination of vertical 4-
compression against concrete with tension in the 1 9-13/16' I
anchor rod and by bending of center plate which 1 (250 mm)
anchored by horizontal compression against II
concrete. (itC `_ ' 11/16'
s (17.5 mm)
Nominal strength of vertical compression of side
plate against concrete: CAT.ND.AFWC3
OFB = OBf'c where:
B =-✓(A2/A1) = ✓16/(1/2"*1 15/16) but<_2.0 M
and f'c= 6 ksi for specified anchoring grout
OFB =0.85*2*6,000 = 10,200 psi 1&i1
Cp„=0.5"*1.9375"*10,200 psi= 9,881# V 'ii•ii
Bar tension strength,nominal r•
Fy = 75ksi (1/4 hard A316)
Tb =0.195 in2*75 ksi = 14,625# C
Cp„controls — P
Mcp„=0.6875"*9,881#= 6,793#" c
Nominal strength from bending of center bar
Bar bending:
Z= 1.9375"*0.93752/4 =0.4257 in3
Fy =45ksi
Mp„ =45 ksi*0.425 in3 = 19,157 #"
EDWARD C.ROBISON,PE
10012 Creviston Dr NW
Gig Harbor,WA 98329
253-858-0855/Fax 253-858-0856 elrobison@narrows.com
CRL Frameless Windscreen Clamps Page 3 of 8
check anchorage:
Center plate is anchored into concrete:
V„= shear strength of bar Cc
V„=A*Fy„=0.195*42ksi= 8,190# Cb 0..11 1 56"
Allowable shear in bar must be reduced for tension:
1>_ (T/Tn)2+(V/V02 Cu Ivb
Vb =V„ [1-(T/T02] = 8190#*[1-(9881#/14625#)2] = 4,452#
Check anchor strength of bar:
C„= Vb+C, and Vb = C,
C„= 2*4,452#= 8,904#
Bearing length along bar for:
FBc = 10,200 psi
L= [Cu/(dbFBc)]/0.85
L= [8,904#/(1/2"*10,200psi)]/0.85 = 2.05" <4" Bar length is adequate
Determine C,
Maximum value for C,if in full compression:
C = 1.56"*1.9375"*10,200 psi* 0.85 = 26,205# >Vb
C,must be balanced with Vb and Cb
a= compression depth for C,
Cb+Vb = Cc and
Cb = (1.56"-a)*1.9375"*10,200 psi
Cc= a*1.9375"*10,200 psi
substituting into above and solving for a:
(1.56"-a)1.9375"*10,200psi+4,452#= 1.9375"*10,200psi*a
(1.56"-a)+0.2253" = a
1.79" = 2a
0.89" = a
Calculate C,from a
Cc=0.89"*1.9375"*10,200psi = 17,589#
Cb = 17,589-4,452 = 13,137#
Calculate the resisted moment by 1M about Cc
Mhn= (1.56"-0.89/2)*4,452+(1.56"/2-0.89"/2)*13,137 = 9,365#"
The total nominal moment strength of the anchorage:
Mn=Mhn+Mcpn= 9,365#"+ 6,793#" = 16,158#"
MS = OMn/1.6 =0.75*16,158#"/1.6 = 7,574#"
Allowable service moment based on bracket anchorage= 7,574#"
EDWARD C.ROBISON,PE
10012 Creviston Dr NW
Gig Harbor,WA 98329
253-858-0855/Fax 253-858-0856 elrobison@narrows.com
CRL Frameless Windscreen Clamps Page 4 of 8
Check moment strength of bracket
Glass to bracket moment resisted by tension in cap screws:
Screw tension is proportional to distance from bottom screw to
screw being considered: 1111
15/16"
1/2" diameter cap screws upper two. �'�, 2 5/16"
1/4" diameter cap screws for lower four.
T" _4,000#(Nominal)
T144= 1,000#(Nominal) 111111 3/8"
VIE
Moment resistance Mn
Mn =4,000#*(5.625"+3.6875"2/5.625")+1,000#*(1.375"2/5.625")*2
M.= 32,169"#+672"#= 32,841
M,=0.8*32841/1.6 = 16,420#"
Check for bending of side plates:
Z= 1.75"*0.56252/4 *2 bars =0.277 in3 (effective dimensions)
Fy =45ksi
M.= 2*0.277*45 ksi = 24,917#"
MS=0.9*24,917/1.6 = 14,016#"
Bracket plate bending strength will control design
Allowable load on each panel:
2 brackets per panel
Mtota, = 2*14,016#" = 28,032#"
Check maximum panel length based on 50 plf loading @ 48" height:
Lp = 28,032#"/(50 plf*48") = 11.68'
Bracket strength will not typically control for maximum load
Brackets will be placed at 1/4 length from each end.
EDWARD C.ROBISON,PE
10012 Creviston Dr NW
Gig Harbor,WA 98329
253-858-0855/Fax 253-858-0856 elrobison@narrows.com
CRL Frameless Windscreen Clamps Page 5 of 8
Check glass strength:
For 50 plf live load along top of glass /
My = 50 plf*48"*2.5' = 6,000#"
MX = 50plf*1.252/2*12"/' =469#"
MXY= -✓(24002
+4692) = 6,018#
/ 1' 3" " l' 3" ,
Determine glass stress: m 2'6 ,
Effective resistance width along XY s
b = 2.5'/(Sin45°)*12"/ft=42.43" T
SX,=42.43"*0.469"2/6 = 1.555 in'
Stress concentration factor for localized bearing:
c1=[(H/h)113]/(H/L/2)
c1=[(48"/5.375")13]/(48"/30")= 1.30
fb = 6,018*1.3/1.555 = 5,030 psi
Checked for wind loading:
W=MS/(H'2/2*L'*12"/ft)
MS= 14,016#" from page 4
Glass moment:
My =W*H'*H"/2*L'/2
Mx =W*H'*LZ*Lc"/2
MXY= (My2+MX2) 1/2
fb =MXY/SXY* c1
Allowable wind load for 48"high panel x 5' long:
W= 14,016#"/(4'2/2*5'*12"/ft) = 29.2 psf
MY = 29.2*4'*48"/2*5'/2 = 7,008#"
Mx = 29.2*4'*1.25'*15"/2 = 1,095#"
MXY= (7,0082+1,0952) 1/2=7,093#"
fb = 7,093#"/1.55*1.30 = 5,949 psi
EDWARD C.ROBISON,PE
10012 Creviston Dr NW
Gig Harbor,WA 98329
253-858-0855/Fax 253-858-0856 elrobison@narrows.com
CRL Frameless Windscreen Clamps Page 6 of 8
Allowable Wind load for other panel sizes:
TABLE 1
Allowable bracket moment#" = 7,008
Height ' Length ft W all PSF My lb-in MX lb-in MXy lb-in beff in Cf SXy in3 fb psi
4.25 5 25.9 7008 1030.59 7083 42.43 1.244 1.555 5667
4.5 5 23.1 7008 973.333 7075 42.43 1.198 1.555 5449
5 5 18.7 7008 876 7063 42.43 1.117 1.555 5070
5.5 5 15.4 7008 796.364 7053 42.43 1.100 1.555 4988
6 5 13.0 7008 730 7046 42.43 1.100 1.555 4983
4 4.75 30.7 7008 1040.25 7085 40.31 1.231 1.478 5902
4.5 4.75 24.3 7008 924.667 7069 40.31 1.138 1.478 5444
5 4.75 19.7 7008 832.2 7057 40.31 1.100 1.478 5254
5.5 4.75 16.3 7008 756.545 7049 40.31 1.100 1.478 5247
6 4.75 13.7 7008 693.5 7042 40.31 1.100 1.478 5243
4 4.5 32.4 7008 985.5 7077 38.18 1.166 1.400 5896
4.5 4.5 25.6 7008 876 7063 38.18 1.100 1.400 5550
5 4.5 20.8 7008 788.4 7052 38.18 1.100 1.400 5542
5.5 4.5 17.2 7008 716.727 7045 38.18 1.100 1.400 5536
6 4.5 14.4 7008 657 7039 38.18 1.100 1.400 5531
4 4.25 34.4 7008 930.75 7070 36.06 1.101 1.322 5889
4.5 4.25 27.1 7008 827.333 7057 36.06 1.100 1.322 5871
5 4.25 22.0 7008 744.6 7047 36.06 1.100 1.322 5864
5.5 4.25 18.2 7008 676.909 7041 36.06 1.100 1.322 5858
6 4.25 15.3 7008 620.5 7035 36.06 1.100 1.322 5854
4 4 36.5 7008 876 7063 33.94 1.100 1.244 6244
4.5 4 28.8 7008 778.667 7051 33.94 1.100 1.244 6233
5 4 23.4 7008 700.8 7043 33.94 1.100 1.244 6226
5.5 4 19.3 7008 637.091 7037 33.94 1.100 1.244 6221
6 4 16.2 7008 584 7032 33.94 1.100 1.244 6217
EDWARD C.ROBISON,PE
10012 Creviston Dr NW
Gig Harbor,WA 98329
253-858-0855/Fax 253-858-0856 elrobison@narrows.com
CRL Frameless Windscreen Clamps Page 7 of 8
One Piece Post Option: 1-15/16
Post is attached to 1-15/16"rod Gasket for 3/8 or 1/2' (50 mm)
set into concrete post is screwed • (10 or 12 mm)Glass1
onto threads on top of embedded IMP
bar.
Check bending strength of bar: 9-13/16'
Z=d3/6 = 1.93753/6 = 1.212 in3 (250 mm)
Fy =45 ksi
Mn = 1.212*45ksi= 54,549#"
0
Ms=
M,=0.9*54,549#"/1.6 '
M,= 30,684#"
CAT. NO. AFWC1
Determine strength of anchorage
into concrete:
Moment is resisted by vertical compression against the concrete by the embedded rod.
The grooves on the end of the rod prevent withdrawal.
Minimum embed depth is 6" M
From M about centroid of C1:
D Cl Cu
M„= C1*D(2/3)
Cu= OFB
FB = shear block failure from ACI 318 App D.6.2
FB = 1.4*-✓1.5*7(6/1.9375)02-V(1.9375*3000)*61.5 = 16,860#
Cu=0.85*16,860#= 14.331#
Mn = 14,331#*6*(2/3) = 57,324#"
M,=0.75*57,324/1.6 = 26,871#"
Moment in bracket—bending at base of groove:
Side bars will be same strength as the three piece post because they are the same shape
and material. Therefore post strength will be controlled by bending of upper side bars
and will be the same as for the 3 piece option.
EDWARD C.ROBISON,PE
10012 Creviston Dr NW
Gig Harbor,WA 98329
253-858-0855/Fax 253-858-0856 elrobison@narrows.com
CRL Frameless Windscreen Clamps Page 8 of 8
GLASS STRENGTH
All glass is fully tempered glass conforming to the specifications of ANSI Z97.1,
ASTM C 1048-97b and CPSC 16 CFR 1201. The minimum Modulus of Rupture for the
glass Fr is 24,000 psi. The actual Fr for the tempered glass is 24 ksi to 26 ksi,therefore
the true Safety Factors are larger than the 4.0 shown herein. In accordance with UBC
2406.6 or IBC 2407.1.1 glass used as structural balustrade panels shall be designed for a
safety factor of 4.0. This is applicable only to structural panels (glass provides support to
railing). Other locations the glass stress may be increased by 33% (SF= 3.0) for glass
infill panels. Glass not used in guardrails may be designed for a safety factor of 2.5 in
accordance with ASTM E1300-00.
Allowable glass bending stress: 24,000/4 = 6,000 psi.—Tension stress calculated.
Allowable compression stress = 24,000psi/4= 6,000 psi.
Allowable bearing stress = 24,000 psi/4 = 6,000 psi.
For Glass not subject to human impacts factor of safety is 2.5 therefore:
Fb = 24,000/2.5 = 9,600 psi
Bending strength of glass for the given thickness:
S = 12"* (t)2 = 2* (t)2 in3/ft
6
For 1/2" glass S = 2*(0.496)2 =0.492 in3/ft
Mallowable= 6,000psi*0.492 in3/ft= 2,952"#/ft= 250'#/ft
For side lites, store fronts and similar non-guard applications:
Mallowable= 9,600psi*0.50 in3/ft=4,800"#/ft=400'#/ft
For lites simply supported on two opposite sides the moment and deflection are
calculated from basic beam theory
Mw=W*L2/8 for uniform load W and span L or
Mp = P*L/4 for concentrated load P and span L,highest moment P @ center
EDWARD C.ROBISON,PE
10012 Creviston Dr NW
Gig Harbor,WA 98329
253-858-0855/Fax 253-858-0856 elrobison@narrows.com
REVISIONS
FRAMELESS GLASS WINDSCREEN
SYSTEM (SI )
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1 2mm TEMPERED GLAZING
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1 . 5m MAXIMUM GLASS wQ 3a@
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PANEL WIDTH � ~ as
GLASS PANELS TYPICAL Q w 03
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2 .7 m MAXIMUM /
GLASS PANEL SIZE/
N
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° / CRL FRAMELE :f:'i` w a
�' 25% OF THE 25% OFHE ► SCREE' ' MP W o
PANEL WIDTH 50% OF THE PANEL WIDTH ��� z
Q CO '��'�� NTED IN CONCRETE w
2 w PANEL WIDTH
co / cc
o TOP OF FINISHED o " Z
w M e
• CONCRETE
Z
o co
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°
°
(20.7MPa) MINIMUM SLAB F'c
( 1 50mm) MINIMUM EDGE DISTANCE
(200mm) MINIMUM SLAB THICKNESS DATE: 10-30-08
SCALE 1 :20 DRAWN BY: CH
CHECKED BY: ECR
SCALE: AS SHOWN
JOB#:
SHT 1 OF