Project: S318 Engr: KS Date: Oct 10, 2018 HALF-LAP SPLICE CONNECTION (SMALL DOME ONLY)
"P:\S318 Taiyuan Park\03. Engineering\3.02 Structure Analysis\ 3.02.3 Connection Design\ Splice connections\Taiyuan domes splice connection calcs 180713.sm"
Connection designed to Eurocode (BS EN 1995) U.N.O. All source references refer to this design standard U.N.O.
Design case
Header labels:
Current values being analyzed:
Tension
[DS R4 .rf5]
Compression
Shear (major axis)
[DS R4 .rf5]
Shear (minor axis)
[DS R4 .rf5]
Moment (major axis)
[DS R4 .rf5]
Moment (minor axis)
[DS R4 .rf5]
BEAM GEOMETRY
Bm width
Primary beam depth
Secondary beam depth
Total bm depth
Parallelogram offset
(assume rectangular, conservative for S)
Vertical leg depth
Depth of reduced cross-section
Splice length
SCREW LAYOUT
=
Number of 'moment screws per pack
Number of rows of screws in transverse direction across beam)
Screw spacing in longitudinal direction
End distance
Screw length
Used for tension screws only at the moment (oct 31, KS)
Screw orientation angle to grain
=
Number of tension screws in half-lap
Tension screw orientation angle to grain
SCREW STRENGTHS
'MOMENT' SCREWS
(screw packs at ends of half-lap)
9mm dia Rothoblaas VGZ (cyl) screw in spruce, density= 380 kg/m^3
(Screw spec)
Unit charactistic withdrawal strength (calculated by dividing load capacity by Sg value, embedment length, in RB tables)
[RB design guide VGZ]
Characteristic tensile steel capacity
[RB design guide VGZ]
'TENSION' SCREWS
(screws in middle of half-lap)
11mm dia Rothoblaas VGS (csk) screw in spruce, density= 380 kg/m^3
(Screw spec)
Unit charactistic withdrawal strength (calculated by dividing load capacity by Sg value, embedment length, in RB tables)
[RB design guide VGS]
Characteristic tensile steel capacity
[RB design guide VGS]
WOOD STRENGTH
GL28c
Specified glulam grade
Bending strength
Material factor for glulam member design
Material factor for glulam connections
Material factor for steel
=
Strength modification factor for service and load-duration classes
[Sec. 3.1.3, Tbl. 3.1]
--Short term load duration --Service Class 3 (large dome), kmod=0.7 --Service Class 2 (DM, DS), kmod=0.9
Characteristic shear strength (EU value)
Characteristic compression strength para to grain
NOTCH REINFORCEMENT
Cracking factor for glulam (could be 0.8, this is an add'l safety factor for shear failure, which is a brittle failure mode, accounts for checking or cracks in solid sawn beams mostly, but is also applicable to glulam due to gaps btwn lams)
[IT EN 1995, Italian version]
Notch factor for glulam
[Eq. 6.63]
Effective beam width for cracking under bending shear
Dist from support center to end of notch
Notch inclination
[BS EN 1995 Fig. 6.11]
[Rothoblaas design guide, VGZ calculation example, pg 112]
MATERIAL STRENGTH CALCS
Design bending strength of specified glulam
Design tension strength para to grain
SCREW WITHDRAWAL STRENGTH
Conservative min screw embedment for moment screws
Embedment length for tension screws
Withdrawal strength for moment screws
Withdrawal strength for tension screws
STEEL TENSILE STRENGTH
CONTROLLING MOMENT SCREW STRENGTH
Controlling capacity for moment screws
Controlling capacity for tension screws
Effective moment screw qty accounts for group effect
[Eq. 8.34,35]
Effective tension screws, screw qty accounts for group effect
Design withdrawal capacity (vertical direction) of screw pack at either end of splice (accounts for angle to grain)
Design withdrawal capacity (horizontal direction) of tension screw pack at middle of splice (accounts for angle to grain)
LATERAL SCREW STRENGTH
(for 9mm VGZ, min embedment of 125 ea side)
[Rothoblaas design guide]
Lateral design strength of screw
Section modulus of gross section
Section modulus of reduced section
Moment arm btwn screw pack CLs
Section modulus of gross parallelogram section
Section modulus of reduced parallelogram section
Reduction in elastic section modulus from gross to reduced cross section
Bearing area of skinny ends of half-laps
Design compression strength of specified glulam parallel to grain
Design compression stress
Results for:
Lateral screw utilization
(Withdrawal force on screws)
Screw withdrawal utilization
(Withdrawal force on screws)
Screw withdrawal utilization
[BS EN 1995 Sec. 8.7.3]
"(1) For screwed connections subjected to a combination of axial load and lateral load, expression (8.28) should be satisfied."
Design withdrawal capacity of screws (whether screw pack only or add'l tension screws)
Design shear capacity of screw pack
Design withdrawal load
Design lateral load
Interaction formula
Strong axis wood bending failure
Weak axis wood bending failure
SHEAR STRESS AT GROSS CROSS SECTION USING H_effective AND K_v(A-A)
Ratio used in the calculation of Kv below
Notch reduction factor
Factored shear strength
Applied shear stress for a rectangular cross section
Shear stress utilization at gross cross-section A-A
SHEAR STRESS AT REDUCED CROSS SECTION (B-B)
Applied shear stress for a rectangular cross section
Factored shear strength
Shear stress utilization at gross cross-section B-B
TENSION PERP TO GRAIN
Tension perp to grain force used below to design the screw reinforcement
[needs ref]
SCREW REINFORCMENT DESIGN
ASSY VG CYL 8x360(FT cyl)
Screw model
Screw dia.
Screw length
Spec'd no. of connectors
(Reduced for 60 deg angle)
Unit withdrawal strength
[Tbl. FR.1.1, MyTiCon Screw Design Guide 2018]
Thread engagement head side
change to formula to account for where screws will be installed
(vertical component slightly less than 130mm)
Thread engagement tip side
Withdrawal screw head side
Withdrawal screw tip side
[Tbl. FR.3.1, MyTiCon Screw Design Guide 2018]
Steel tensile
Controlling characteristic resistance
Design resistance/screw
Design resistance
Fracture force
Notch reinforcment screw utilization
[BS EN 1995 Sec. 6.2.3]
ALL RESULTS
Shear stress utilization at gross cross-section A-A
Shear stress utilization at gross cross-section B-B
Notch reinforcment screw utilization
Lateral screw utilization
Screw withdrawal utilization
Interaction axial and lateral on screw
Strong axis wood bending failure
Weak axis wood bending failure
THINGS TO ADD/CONSIDER: 1. Wk/strong axis bending interaction 2. Screw angle contribution to tension capacity DONE---3. Add bearing para to grain 4. Check to see if add'l shear is created that would cause the notch to split. 5. Check model to see if the downstand leg dims are actually correct.