AISI NHERI Diaphragm Supplement

June 30, 2020 Update to AISI

Hernan Castaneda1 and Kara D. Peterman2

1Graduate Research Assistant, University of Massachusetts Amherst2Assistant Professor, University of Massachusetts Amherst

General Project Update

• We are all healthy and productive!

• Frontloading modeling efforts during Work From HomeJournal paper 1 (joist-ledger connections) on path to publication – coming soonThis summer, extended to full diaphragm system models predictions for future specimens

• Cantilever test rig (supported by SDI + Verco/Vulcraft) fabrication delayed due to COVID, design complete

Movement happening now things are opening up a bit

• Lab @UMass re-opened 06/22 at 25% capacity

• UCSD “latest and greatest” timeline: testing (in 6 DOF) Dec 2021/Jan 2022.

Brack Lab (UMass): Diaphragm Test Rig Top view

Fix End

Actuator

Free End

Specimen

Frame

Pin

Connection

RollerFront view

Strong

Floor

Brack Lab (UMass): Actuator and Roller Connection

Roller

Actuator

Bracket

Attachment

Support

Beam

Brack Lab (UMass): Rollers

Prevent

Uplift

Roller Dolly, Swivel

Platform, 25000 lb.

3 ¼" Wheel Dia.

• Roller support aimed

at 10% of actuator

capacity: 10 kips

Brack Lab (UMass): Rig – Fix Connection

Rig-Fixed Support

Brack Lab (UMass): Rig – Actuator Connection

Rig-Actuator

Brack Lab (UMass): Rig - Attachments

Rig-Specimen

Rig-Actuator Actuator-Support Beam Rig-Fixed Support

Brack Lab (UMass): Rig – Specimen Width Flexibility

Brack Lab (UMass): Test Rig [15’X15’] – Motion

• 10 in Stroke

• Δz = 0.26 in

• Tilt angle = 1° Click to play videos

Brack Lab (UMass): Test Rig [10’X15’] – Motion

• 10 in Stroke

• Δz = 0.26 in

• Tilt angle = 1° Click to play videos

Brack Lab (UMass): Test Rig

Fix Beam

Actuator

Support

Fix

Support

Free Beam

Transverse Beam

Roller

Support

Estimation of Weight, W:

Test Rig Frame

ComponentW

(lbs) (Kg)

Free Beam 2834 1286

Fix Beam 2558 1160

2 Transverse Beam 4019 1823

Total 9412 4269

Supports + Attachments + Plates

ComponentW

(lbs) (Kg)

Actuator Support 1002 455

2 Fix Support 1223 555

Roller Support 551 250

Total 2776 1259

Note:

- Weight is calculated assuming a density value of 0.2836 lbs/in3

- Nominal thickness of components varies between ¾” and ½”

- Some dimensions are approximated

Ledger

(1200T200-97)

Clip-Angle

(1.5X1.5-54)

Ledger

(1200T200-97)

Joist

(1200S200-97)

Diaphragm FEM 9/16” Deck on CFS Joist: Geometry

• Material properties steel:• Shell Elements: S4R

• A three-dimensional Finite Element Model (FEM) was developed using ABAQUS.

- E = 29500 ksi

- Fy = 50/60 ksi (EPP)

- ν = 0.3

Diaphragm FEM: Contact Interactions

• Contact behavior:

Clip-Angle

Ledger Web

Clip-Angle

Joist WebJoist Web

Ledger Web

Joist Flange

Ledger Flange

- Tangential:

C.O.F. = 0.2

- Normal:

Non-linear penetration pressure

Deck Side-Lap

Deck

Ledger Flange

Deck

Joist Flange

Diaphragm FEM: Fastener Connections• Connector elements:

- Wires

Clip-Angle

Ledger Web

(Screw #10)

Clip-Angle

Joist Web

(Screw #10)

Ledger Flange

Joist Flange

(Screw #10)

Ledger Flange

Joist Flange

(Screw #10)

Multi-Linear

Elastic

Damage Failure

Node

iNode

j

Connector Element Behavior

Shear

(Tao 2017)

Shear

(Tao 2017)

Pull-Out

(Castaneda 2020)

zx

y

Fastener elastic behavior

Fastener Pull-Out 97-54

2

1Fo

rce,

P [

kN

]

0

3

Displacement, δ [mm]

06 12 18

P1

P2

P3

Ppeak

Pfinal

9754-R1

9754-R2

9754-R3

ABAQUS

Experimental response

Support

Connection

(Screw #12)

Diaphragm FEM: Fastener Connections

Pattern 30/4

30”

Edge

Connection

@ 8” o.c.

(Screw #12)

Side-Lap

Connection

@ 12” o.c.

(Screw #10)

Support Connection Pattern

“Fix” strips

@ 2 ft o.c.

[Ux=Uy=Uz=0]

Load strips

[Uy=Uz=0; Ux=Applied Displacement]

Diaphragm FEM: Loading and Boundary Conditions

End Ledger Web

[Uz=0]

End Ledger Web

[Uz=0]

x

z

P

Diaphragm FEM: Results

Connector

Resultant Force

Stress Contour

Failure @

Corner Fastener

Failure @

Side-Lap Fastener

Diaphragm FEM: Results

• Effect on fastener

modeling shear behavior:

- Ductile: Consider post

peak experimental

response

- Brittle: Fastener

suddenly fails upon

reaching peak

experimental response

Diaphragm FEM: ResultsEdge Connection

@7.5”

Field Connection

@15”

3/8”

Diaphragm FEM: Results

Joist @ 2ft

Joist @ 4ft

Joist @ 8ft

Warping

Warping

Buckling

Diaphragm FEM: Results

Specimen 10ftX8ft: Joist @ 8ft

Ledger

Joist

Comments / Questions?

Email me: kdpeterman@umass.edu