Development of a standard joint fixity

test

Prof. Ir.-arch. Dirk R.W. MartensTechnische Universiteit Eindhoven

CIB W023 meeting Prague 2005

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Contents

1.introduction2.classification of wall-floor-joints

3.standards in Europe4.new concepts

5.experimental research programme

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1.introduction

load bearing capacity of masonry walls:

width of the wall: tlength of the wall: beffective height: heff

design value of compressive strength: fdeccentricity of in-plane load: e

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compressive strength of unit compressive strength of mortarfb fm

characteristic value ofcompressive strength of masonry

fk

design valuefd = fk/γM

reduction for eccentricity reduction for 2nd order effect

design value of load bearing capacity of wall

NRd = φ b t fd

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NRd = φ b t fd

How to determine e0 ?(first order eccentricity)

theory of non-linearelasticity

simplifiedmethods

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Non-linear theory of elasticity

Use of non-linear M-N-κ-diagram and takinginto account the second order effect

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Simplified method according to Annex C of EC 6 simplified frame analysis

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Simplifiedmethodaccording toAnnex C of EC 6

( ) ( )⎥⎦⎤

⎢⎣

⎡−

⋅−

−⋅

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+⋅⋅

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=1414 4

244

3

233

4

443

3

333

2

222

1

111

1

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1 nlw

nlw

lIEn

lIEn

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M

41 k

−=η 2

2

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1

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≤⋅

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⋅+

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=

hIEn

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lIEn

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kJoint fixityreductionfactor

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The second order effect should bedetermined independently from e0 (at mid-height of wall)

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Problems:

- the simplified method has not been evaluated extensively by experiments

-the theory is only valid for continuousfloors: in practice other floor types are used

- there are no recommendationsconcerning the wall-floor interface

- there is no standard test method forthe determination of the joint fixityreduction factor

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floor type Wall-floor-interface relative bearing length

No interface

(cold joint) bearing length = t

Continuous support

- Concrete slab: two-way span

- Semi-prefabricated floor element

- Prefabricated floor element

Mortar joint

Elastic interface layer (neoprene layer, …)

0,5 t < bearing length < t

Central concrete core

Discontinuous support

- Timber floor (joists)

- Beam and pot floor

- TT-floors

- Steel deck with concrete topping Steel bar in mortar joint

bearing length < 0,5 t

2. Classification of wall-floor-joints

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iesFloor type:

Discontinuous support with semi-prefabricated floor element

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Discontinuous support with spaced beamelements (beam and pot floor system)

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Wall-floor interface: mortar layer and rebar or rubber bearing strip or central concrete core

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Relative bearing depth

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3. Standards in Europe

Dutch codeBelgian codeBritish code

Norwegian codeSwiss codePolish codeEurocode

ISO/DIS 9652-1

No uniform design code !

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1.Eccentricity relative to bearing depth

No interaction?

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2. Simplified frame analysis

Joint fixity factor?

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3. Design charts

Assumptions?

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Theoretical modellingJäger and Baier

MatysekSahlinTU/e

Standard test set-up for joint fixitySahlinTU/e

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Concept Jäger and

Baier

Rotationalspring

characteristics

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Matysekfinite element calculations: influence

of wall-end cracking is negligibleif the precompression > 0,3 MPa

Sahlinexperimentally determined joint

rotation relationship

TU/eintegrated method: wall-floor

interaction and 2nd order effect

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Standard test set-up according

to Sahlin

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set-up according to

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- Curvature of the floor slab is more realistic- larger curvatures can be evaluated- larger loads can be transfered to the wall

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5. Experimental research programme

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iesWhich parameters have to be

evaluated?

1. joint type2. relative wall-floor stiffness ratio3. masonry material4. floor type5. interface type6. loading ratio7. relative bearing depth

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ies1. Joint type

1.1. joint type 11.2. joint type 21.3. joint type 31.4. joint type 41.5. joint type 5

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ratio

2.1. 0<k≤1

2.2. 1<k ≤ 2

2

2

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1

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4

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3

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k

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3. Masonry material

3.1. grouping of masonry units:1, 2 or 3

3.2. type of mortar: general purpose mortarlight weight mortarthin layer mortar

3.3. material of the unitsclay brickcalcium silicateaggregate concreteautoclaved aerated concretenatural stone

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4.1. continuous support

4.2. discontinuous support

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5.1. no interface5.2. mortar joint5.3. elastic interface layer5.4. other interface

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6. Relative normal force

6.1. 0 < νd ≤ 0,40

6.2. 0,40 < νd ≤ 0,65

6.3. 0,65 < νd ≤ 1,00

d

dd ftb

N⋅⋅

=ν

00.10.20.30.40.50.60.70.80.9

1

0 0.02 0.04 0.06 0.08 0.1 0.12 0.14

μ

12

3

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7.1. 0 < db ≤ 0,5

7.2. 0,5 < db < 1

7.3. db = 1

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iesWhich experimental research has

to be done?

- full scale tests: callibration of small scale tests

- small scale tests = standardjoint fixity test

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Test set-up full scale test

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measurements

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Joint fixity tests

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parameter S1 S2 S3 S4 M1 M2 M3 M4

k 0,5 x x x x x x

1.0 x x x x x x x x

1,5 x x x x x x

2.0 x x x x x x

material group 1 calcium silicate x x x x x x

thin layer mortar

group 2 perforated clay block x x x x

general purpose mortar

support hollow core floor slab x x x x x x

semi-prefabricated floor slab x x

interface cold joint x x x x

mortar joint x x x x x x

νd 0,2 x x x x x x

0,4 x x x x x x x x

0,6 x x x x x x

db 0,5 x x

1.0 x x x x x x x x

Overview of research programmes

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Acknowledgements

Dutch Masonry FoundationPieter van Musschenbroek Laboratory