Design for Deconstruction for Sustainable Composite Steel- Concrete - - PowerPoint PPT Presentation

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Design for Deconstruction for Sustainable Composite Steel- Concrete - - PowerPoint PPT Presentation

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Design for Deconstruction for Sustainable Composite Steel- Concrete Floor Systems Jerome F. Hajjar, Lizhong Wang Department of Civil and Environmental Engineering Northeastern University Mark D. Webster Simpson Gumpertz and Heger, Inc.

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SLIDE 1

Design for Deconstruction for Sustainable Composite Steel- Concrete Floor Systems

Jerome F. Hajjar, Lizhong Wang

Department of Civil and Environmental Engineering Northeastern University

Mark D. Webster

Simpson Gumpertz and Heger, Inc. Advances in Steel-Concrete Composite Structures (ASCCS 2018) Valencia, Spain, June 29, 2018

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SLIDE 2

End-of-life of Construction Materials

End-of-life of construction materials

Image from SteelConstruction.Info

Sustainable Building Systems

Introduction DfD Floor System Conclusions Design Pushout Tests Beam Tests

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SLIDE 3

Composite Floor System

  • Conventional composite floor systems are cost-effective solutions for multi-story buildings
  • The integration of steel beams and concrete slab limits separation and reuse of the

components

  • Proposed DfD System: Clamp precast planks to steel beams/girders in a steel framing system
  • Both the steel members and the precast planks may be reused

Precast concrete plank Cast-in channels Steel beam Deconstructable composite beam prototype Clamps Tongue and groove side joint Bolts a) Plank perpendicular to the steel beam

24'' 6'' 12'' 6'' 6''

b) Plank parallel to the steel girder

12'' 12'' 12'' 12'' 12'' 6''

Precast concrete plank cross section

Design for Deconstruction

Introduction

DfD Floor System

Conclusions Design Pushout Tests Beam Tests

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SLIDE 4

DfD Floor System

Goal: Achieve nearly 100% direct reusability for composite floor systems within the context of

bolted steel framing systems

30' 30' 30' 30' 30' 30' 10' 10' 10' 10' 10' 10' 10' 10' 10'

Typical floor plan for DfD system Example of deconstructable bolted connection ConXtech moment connection

Image from ConXtech Website

Design for Deconstruction

Introduction

DfD Floor System

Conclusions Design Pushout Tests Beam Tests

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SLIDE 5

Test Program

  • Pushout tests: evaluate a wide range of parameters and formulate strength design equations

for the clamping connectors

  • Beam tests: study the clamp connector behavior and associated composite beam strength and

stiffness for different levels of composite action

Precast Concrete Planks Steel Beam Spreader System Composite beam test setup

Design for Deconstruction

Pushout test setup Reaction Angle Precast Concrete Plank Steel Beam Self-reacting Frame Actuators Introduction

DfD Floor System

Conclusions Design Pushout Tests Beam Tests

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SLIDE 6

Pushout Test Setup Pushout Test Configuration

Elevation View Load Plan View Load Introduction DfD Floor System Conclusions Design Pushout Tests Beam Tests Pushout test setup Reaction Angle Precast Concrete Plank Steel Beam Self-reacting Frame Actuators

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SLIDE 7

Pushout Test Matrix Pushout Test Parameters

Series Specimen Test parameters Bolt diameter Number of T bolts Reinforcement configuration Shim M 2-M24-T4-RH M24 4 Heavy No M 3-M24-T4-RH-S M24 4 Heavy Yes M 4-M24-T6-RH M24 6 Heavy No M 5-M20-T4-RH M20 4 Heavy No C 6-C24-T4-RH M24 4 Heavy No C 7-C24-T4-RL M24 4 Light No C 8-C24-T4-RH-S M24 4 Heavy Yes C 9-C24-T6-RH M24 6 Heavy No C 10-C20-T4-RH M20 4 Heavy No

Three-channel specimen Two-channel specimen with shims

Steel shims

Introduction DfD Floor System Conclusions Design Pushout Tests Beam Tests

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SLIDE 8

Loading protocols

  • Monotonic test: Displacement control
  • Cyclic test:
  • Displacement control
  • Emulate AISC 341-10 K2.4b β€œLoading

Sequences for Beam-to-Column Moment Connection”

Reinforcement pattern

  • Light pattern: Contains reinforcement

designed for gravity loading only

  • Heavy pattern: Supplementary

reinforcement bridges all potential concrete failure planes

Pushout Test Parameters

6 12 18 22 26 30 34 38 42 46 50 54

Cumulative cycles

  • 150
  • 100
  • 50

50 100 150

Slip (mm)

  • 6
  • 4
  • 2

2 4 6

Slip (in.)

75% of slip load 37.5% of slip load 50% of slip load 0.5 mm 1.0 mm 2.0 mm 4.0 mm 8.0 mm 0.75 mm 6.0 mm 1.5 mm 3.0 mm 24 mm 12 mm 48 mm 0.375 mm/min 1.5 mm/min 0.75 mm/min 3 mm/min 6 mm/min 12 mm/min 24 mm/min 64 mm 96 mm 128 mm 16 mm 32 mm 48 mm/min

Introduction DfD Floor System Conclusions Design Pushout Tests Beam Tests

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SLIDE 9

Monotonic Test Results Pushout Test Results

  • The shear strength of a M24 clamp is 98.3 kN, while the strength of a 19 mm (3/4 in.) diameter shear stud

embedded in a 27.58 MPa (4 ksi) solid concrete slab is 95.6 kN.

  • The very large initial stiffness of the clamps reduces the slip at the steel-concrete interface at the

serviceability and enhances the stiffness of the composite beams.

  • The M24 clamps can retain almost 80% of the peak strength even at a slip of 125 mm, while shear studs

usually fracture under much less deformation (~8 mm).

  • The smaller M20 clamps are prone to rotate. The strength degradation starts at a slip of 17.3 mm, which is

usually much larger than the maximum slip demand on shear connectors in composite beams.

30 60 90 120 150 180 210 240 270

Slip (mm)

80 160 240 320 400 1 2 3 4 5 6 7 8 9 10 11

Slip (in.)

15 30 45 60 75 90

M24-T4-RH

30 60 90 120 150 180 210 240 270

Slip (mm)

50 100 150 200 250 1 2 3 4 5 6 7 8 9 10 11

Slip (in.)

10 20 30 40 50 60

M20-T4-RH Introduction DfD Floor System Conclusions Design Pushout Tests Beam Tests

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SLIDE 10

Cyclic Test Results Pushout Test Results

  • Strength reduction similar to shear studs which exhibit lower strength and ductility when

subjected to cyclic loading

  • The peak load reduces due to lowering of frictional coefficients and release of bolt tension

caused by abrasion between the components.

  • Clamps have the potential to connect composite diaphragms and collector beams and could

be designed as inelastic components to dissipate energy.

Specimens C24-T4-RH and C24-T4-RL

  • 150 -120 -90 -60 -30

30 60 90 120 150

Slip (mm)

  • 80
  • 60
  • 40
  • 20

20 40 60 80

Light reinforcement Heavy reinforcment

  • 6
  • 5
  • 4
  • 3
  • 2
  • 1

1 2 3 4 5 6

Slip (in.)

  • 20
  • 15
  • 10
  • 5

5 10 15 20

  • 24
  • 18
  • 12
  • 6

6 12 18 24

Slip (mm)

  • 320
  • 240
  • 160
  • 80

80 160 240 320

  • 1
  • 0.75
  • 0.5
  • 0.25

0.25 0.5 0.75 1

Slip (in.)

  • 80
  • 60
  • 40
  • 20

20 40 60 80

Specimen C24-T4-RH (within 25 mm slip) Introduction DfD Floor System Conclusions Design Pushout Tests Beam Tests

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SLIDE 11

Composite Beam Test Beam Test Setup

Composite beam # Bolt size # of channels per plank Steel beam section Reinforcement configuration Number of bolts (clamps) Percentage of composite action Nominal Actual 1-M24-2C-RH M24 2 W14x38 Heavy 56 86.7% 82.7% 2-M24-1C-RL M24 1 W14x38 Light 30 47.3% 45.1% 3-M20-3C-RL M20 3 W14x26 Light 90 129.2% 137.8% 4-M20-1C-RL M20 1 W14x26 Light 30 43.0 % 43.8% Composite beam test setup Introduction DfD Floor System Conclusions Design Pushout Tests Beam Tests

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SLIDE 12

DfD Composite Beam Tests at STReSS Lab

  • Vertical load vs.

vertical deflection

  • Load transfer occurs

through the clamps without causing damage to either the steel beam or concrete planks

DfD Beam Specimen 1: Fully Composite DfD Beam Specimen 4: Partially Composite Overview of Specimen View Underneath Specimen Showing Clamps in Action

Engineering Sustainability: DfD

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SLIDE 13

Load-Deflection Curves Beam Test Results

50 100 150 200 250 300 350

Deflection (mm)

100 200 300 400 500 600

(9.65 mm, 96.39 kN) Beam yielding Slip First bang Concrete crushing

3 6 9 12 15

Deflection (in.)

20 40 60 80 100 120 140

AISC prediction

Test 1-M24-2C-RH

50 100 150 200 250 300 350

Deflection (mm)

100 200 300 400 500

(11.43 mm, 96.39 kN) Slip Beam yielding Concrete crushing at east side First bang Concrete crushing at west side

3 6 9 12 15

Deflection (in.)

20 40 60 80 100 120

AISC prediction

Test 2-M24-1C-RL

50 100 150 200 250 300 350 400 450

Deflection (mm)

50 100 150 200 250 300 350 400

(20.07 mm, 96.39 kN) Beam yielding Concrete crushing at west side Concrete crushing at east side

3 6 9 12 15 18

Deflection (in.)

15 30 45 60 75 90

AISC prediction

Test 3-M20-3C-RL

50 100 150 200 250 300 350

Deflection (mm)

50 100 150 200 250 300

(22.61 mm, 96.39 kN) Slip Beam yielding Concrete crushing at east side First bang Concrete crushing at west side

3 6 9 12 15

Deflection (in.)

20 40 60 80

AISC prediction

Test 4-M20-1C-RL Introduction DfD Floor System Conclusions Design Pushout Tests Beam Tests

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SLIDE 14

Beam Test Results

Localized concrete crushing Deconstructed steel beam

Test Results

Specimen # Stiffness (kN/mm) Moment (kN-m) Maximum Slip (mm) Test AISC Test/AISC Test AISC Test/AISC West Side East Side 1-M24-2C-RH 9.24 8.67 1.07 777 767 1.01 5.94 6.43 2-M24-1C-RL 7.76 6.81 1.14 634 632 1.00 8.18 6.45 3-M20-3C-RL 6.46 5.99 1.08 494 510 0.97 0.46 0.23 4-M20-1C-RL 6.08 4.43 1.37 476 400 1.19 8.79 8.08

  • Large initial stiffness demonstrated by the load-slip curves
  • Small slip at full service loading (dashed lines)

2 4 6 8 10

Slip (mm)

100 200 300 400 500 600

T1W T1E T2W T2E T3W T3E T4W T4E

0.1 0.2 0.3 0.4

Slip (in.)

20 40 60 80 100 120 140

Applied load versus slip

Test 1 Test 2 Test 3 Test 4

Introduction DfD Floor System Conclusions Design Pushout Tests Beam Tests

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SLIDE 15

Behavior of T-bolts

Beam Tests

140 170 200 230 260

Bolt tension (kN)

100 200 300 400 500 600

Northeast end bolt Southeast end bolt Northwest end bolt Southwest end bolt Center bolt

30 35 40 45 50 55 60

Bolt tension (kips)

20 40 60 80 100 120 140

AISC minimum bolt tension Test 1-M24-2C-RH Full service loading

  • The bolt tension reduction is insignificant at the serviceability of the beam specimens.
  • The bolt tension reduction is greater for the center bolts than the end bolts.

160 180 200 220 240 260

Bolt tension (kN)

100 200 300 400 500

Northeast end bolt Southeast end bolt Northwest end bolt Southwest end bolt Center bolt

35 40 45 50 55 60

Bolt tension (kips)

20 40 60 80 100 120

Full service loading AISC minimum bolt tension Test 2-M24-1C-RL

120 140 160 180 200

Bolt tension (kN)

100 200 300 400

Northeast end bolt Southeast end bolt Northwest end bolt Southwest end bolt Center bolt

25 30 35 40 45

Bolt tension (kips)

15 30 45 60 75 90

AISC minimum bolt tension Full service loading Test 3-M20-3C-RL

120 140 160 180 200

Bolt tension (kN)

50 100 150 200 250 300 350

Northeast end bolt Southeast end bolt Southwest end bolt Center bolt

25 30 35 40 45

Bolt tension (kips)

20 40 60 80

Full service loading AISC minimum bolt tension Test 4-M20-1C-RL

Introduction DfD Floor System Conclusions Design Pushout Tests Beam Tests

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SLIDE 16

Behavior of T-bolts Bolt Tension Reduction

  • High strength T-bolts are yielded after pretensioning.
  • Shear force releases the axial deformation and tension of the bolts.
  • The damage to the steel flange and clamp

teeth in the cyclic pushout specimen releases the bolt tension.

  • 25 -20 -15 -10
  • 5

5 10 15 20 25

Slip (mm)

40 80 120 160 200 240

  • 1
  • 0.75 -0.5 -0.25

0.25 0.5 0.75 1

Slip (in.)

10 20 30 40 50 60

Pushout specimen C24-T4-RL AISC minimum bolt pretension

Pushout Tests

Introduction DfD Floor System Conclusions Design Pushout Tests Beam Tests

𝑔

  • 𝑔
  • 𝑔
  • 𝑔
  • 𝑔

+ 𝑔

  • 𝑔

+ 𝑔

  • 𝑔
  • 𝑔
  • 𝑔
  • 𝑔
  • 𝐺
  • 𝐺
  • Free body diagram

clamp tail clamp teeth

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SLIDE 17

Design Recommendations Shear Strength of Clamping Connectors

Introduction DfD Floor System Conclusions Design Pushout Tests Beam Tests

Fixed ends Loaded flange Symmetric boundaries

  • Bolt tension is distributed to clamp teeth and clamp tail.
  • Bolt tension varies throughout the test.

15 30 45 60 75 90 105

Slip (mm)

80 160 240 320 400

Load (kN)

Test Analysis 0.5 1 1.5 2 2.5 3 3.5 4 4.5

Slip (in.)

15 30 45 60 75 90

Load (kips)

Load-slip curve comparison

Specimen:

  • Prior to slip, the shear resistance comes from static friction.
  • After slip occurs, bearing, induced by clamp teeth digging into steel flanges, is another contributor to the

shear resistance. FEM:

  • A single frictional coefficient of 0.35 is assumed.
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SLIDE 18

Design Recommendations

Introduction DfD Floor System Conclusions Design Pushout Tests Beam Tests

15 30 45 60 75 90 105

Slip (mm)

0.5 0.55 0.6 0.65 0.7 0.75 0.8 0.85 0.9

Ratio

Clamp 1 Clamp 2 0.5 1 1.5 2 2.5 3 3.5 4 4.5

Slip (in.)

15 30 45 60 75 90 105

Slip (mm)

50 100 150 200 250

Bolt tension (kN)

Bolt 1 Bolt 2 0.5 1 1.5 2 2.5 3 3.5 4 4.5

Slip (in.)

10 20 30 40 50 60

Bolt tension (kips)

  • Bolt tension versus slip
  • Normal force at clamp teeth to bolt tension

ratio versus slip 𝑅 = π‘™π‘™πœˆπΈπ‘ˆπ‘œ Monotonic shear strength design equation: 𝑙 and 𝑙= coefficients accounting for the portion of bolt tension transferred to the clamp teeth and the bolt tension reduction at peak strength, which are 0.70 and 0.67, respectively 𝜈= idealized frictional coefficient at peak strength, which is 0.35 in the pushout tests 𝐸=1.13, a multiplier representing the ratio of the mean installed bolt pretension to the specified minimum bolt tension π‘ˆ= minimum fastener tension given in AISC 360-16 π‘œ= number of slip planes, which is 2

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SLIDE 19

Design Recommendations

Introduction DfD Floor System Conclusions Design Pushout Tests Beam Tests

Deconstructable Composite Beams

  • Elastic stiffness: could be conservatively estimated using a lower-bound moment of inertia
  • Flexural strength: could be calculated using a rigid plastic design method
  • Resistance factor: a factor of 0.9 is proposed for the flexural strength design equation in

accordance with a reliability analysis

Tested-to-predicted Strength Ratio for Pushout Specimens

Cyclic shear strength:

  • A coefficient of 0.8 could be used with the monotonic shear strength.

Specimen Tested strength kN (kips) Predicted strength kN (kips) Ratio 2-M24-T4-RH 98.3 (22.1) 76.1 (17.1) 1.29 3-M24-T4-RH-S 97.9 (22.0) 76.1 (17.1) 1.29 4-M24-T6-RH 96.5 (21.7) 76.1 (17.1) 1.27 5-M20-T4-RH 61.4 (13.8) 52.7 (11.8) 1.17

  • The proposed design equation predicts the peak strength of the clamps conservatively.
  • The difference mainly comes from 𝐸, which is about 1.30 in the pushout tests.
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SLIDE 20

Conclusions

  • A new deconstructable composite floor system is proposed to promote sustainable design of composite

floor systems within bolted steel building construction through comprehensive reuse of all key structural components.

  • 2 and 1.5 turns after a snug-tight condition are recommended for pretensioning the M24 and M20 bolts in

the DfD plank system.

  • The M24 clamps are highly robust under monotonic loading - compared to shear studs that fracture at

much smaller slips (~8 mm), the clamping connectors can retain almost 80% of the peak strength even at 125 mm slip under monotonic loading.

  • The strength of the M20 clamps declines quickly because the clamps are prone to rotate as the beam
  • moves. Nonetheless, the slip at which the curve starts to descend is much larger than the slip demand on

the clamping connectors in composite beams.

  • The clamps could be utilized to connect composite diaphragms and collector beams due to their excellent

energy dissipating capacity.

  • All the beams deflected to L/25 and behaved in a ductile manner. The tested flexural strength of the beams

is close to that predicted by the AISC design equations. The stiffness of the specimens is slightly underestimated by a lower-bound moment of inertia.

  • Bolt tension reduction induced by shear force is insignificant at the serviceability of the beams and

generally stayed above minimum bolt pretension at ultimate load; further study is needed for cyclid loading

Introduction DfD Floor System Conclusions Design Pushout Tests Beam Tests

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SLIDE 21

Thank You

Precast concrete plank Cast-in channels

Steel beam

Deconstructable composite beam prototype Clamps Tongue and groove side joint Bolts Precast Concrete Planks Steel Beam Spreader system Composite beam test setup