Tests on existing wall ties: shear and axial tests

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Tests on existing wall ties: shear and axial tests

Messali, F.; Skroumpelou, G.; Esposito, R.

Publication date

2017

Document Version

Final published version

Citation (APA)

Messali, F., Skroumpelou, G., & Esposito, R. (2017). Tests on existing wall ties: shear and axial tests. Delft

University of Technology.

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Project number C31B67

File reference C31B67-WP6-2

Date 04 January 2017

Corresponding author Francesco Messali

(f.messali@tudelft.nl)

TU Delft Large-scale testing campaign 2016

TESTS ON EXISTING WALL TIES: SHEAR

AND AXIAL TESTS

Authors: Francesco Messali, Georgia Skroumpelou, Rita Esposito

Cite as: Messali, F. Skroumpelou, G., Esposito, R. (2017). Tests on existing wall ties: shear and axial tests. Report number C31B67WP6-2, 04 January 2017. Delft University of Technology.

This document is made available via the website ‘Structural Response to Earthquakes’ and the TU Delft repository. While citing, please verify if there are recent updates of this research in the form of scientific papers.

All rights reserved. No part of this publication may be reproduced, stored in a retrieval system of any nature, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior written permission of TU Delft.

TU Delft and those who have contributed to this publication did exercise the greatest care in putting together this publication. This report will be available as-is, and TU Delft makes no representations of warranties of any kind concerning this Report. This includes, without limitation, fitness for a particular purpose, non-infringement, absence of latent or other defects, accuracy, or the presence or absence of errors, whether or not discoverable. Except to the extent required by applicable law, in no event will TU Delft be liable for on any legal theory for any special, incidental consequential, punitive or exemplary damages arising out of the use of this report.

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Version 01 - Final 04/01/2017

1 Introduction

The current document reports the outcomes of a series of tests performed on replicated wall ties reproducing existing connections in cavity wall.

The campaign aims at providing a complete characterization of the behaviour of the connections under either axial (tensile and compressive) or shear cyclic loading. The obtained results completes the outcomes of the experimental campaign performed in 2015 on existing wall ties (whose outcomes are shortly reported in [1]) and will be used as inputs to calibrate the numerical models, which simulate the interaction between the inner and outer leaves of a cavity wall.

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2 Construction of the specimens

The samples were built in the Stevin II laboratory at the Delft University of Technology on 16/08/2016 (Figure 1, Figure 2).

The construction followed the prescription reported in the protocol [1].

The mortar was prepared by adopting fixed water content per bag of mix: 2.8 l/bag for calcium silicate masonry and 3.7 l/bag for clay masonry.

During the construction, the temperature and the relative humidity were measured. For every mortar cast, the fluidity of the mortar was determined in agreement with EN 1015-3:1999 [2].

Mortar samples were collected to evaluate the flexural and compressive strength.

Figure 1 – Calcium silicate specimens

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3 Axial tests on existing wall ties

Testing procedure

Description of the specimens

L-shaped ties with a diameter of 3.6 mm and a length of 200 mm are used; they are produced by Gebr. Bodegraven BV (GB) and are named UNI-L spouwankers 200, 3.6Ø. These ties are the same ties tested during the experimental campaign of 2015 [3].

The tests refer to cavity walls composed by two masonry walls having each leaf a thickness of approximately 100mm and a cavity space of 80mm. The L-shaped part of the tie is embedded in the inner leaf, which is usually made of calcium silicate masonry or clay masonry, while the zigzag part lies in the outer leaf made of clay masonry. To test a complete connection, two typologies of specimens (with a single tie embedded in the mortar joint of a masonry couplet) are considered:

 Calcium Silicate specimens (TUD_ANC-1i, i = 1, …, 7): hooked part of the tie embedded in a calcium silicate masonry couplet, representing a possible condition for the inner leaf of a cavity wall (anchoring length: 70 mm) (Figure 3a);

 Clay specimens (TUD_ANC-2j, j = 1, …,7): Zigzag part of the tie embedded in a clay masonry couplet, representing a possible condition for the inner leaf of a cavity wall (anchoring length: 50 mm) (Figure 3b).

(a) (b)

Figure 3 – Tie specimens: Calcium Silicate specimens (TUD_ANC-1i, i = 1, …, 7) (a); Clay specimens (TUD_ANC-2j, j = 1, …, 7) (b).

The dimensions for each typology of specimen are provided in Table 1. Table 1 – Dimensions of test specimens.

Dimensions Calcium Silicate specimens _{(TUD_ANC-1i, i = 1, …, 7)} _{(TUD_ANC-2j, j = 1, …, 7)}Clay specimens

ls (mm) 212 210

hs (mm) 152 110

ts (mm) 102 100

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Version 01 - Final 04/01/2017 Test set-up

The test apparatus is presented in Figure 4 and Figure 5, and comprehends:

 Simple supports for the specimen, for both tensile and compressive applied forces. The support system consists of two couples of hardwood bearers (61_{) placed on the top and bottom surfaces of}

the specimen (1). The bearers are supported by two horizontal steel plates (5) which are connected each other by means of steel bolts (7). The lower plate is clamped to a contrast beam (13), which prevents any movement of the supports. The hardwood bearers do not apply any restraint against splitting of the specimen (apart from the friction generated at the reaction due to the applied load, as suggested by EN 846-5:2012).

 A means of applying and maintaining a constant compressive stress on the couplet. The force is provided by a hydraulic jack (11) acting in the horizontal direction and perpendicular to the bed joint plane. The system is self-equilibrated by four threaded bars (82_{) connecting the vertical plates (4),}

so that two L-angles (12) are sufficient to provide a horizontal connection the supporting beam (13).  A test machine to apply the vertical load. The pull-out load acts in a vertical direction using displacement controlled apparatus. The apparatus is composed by a 4.5 tons jack and a double cylindrical joint (between the load cell and the clamp), which reduce possible eccentricities and prevent torsion failures of the tie during loading (Figure 6a). The machine is provided with a clamp (3) for gripping efficiently the free end of the tie (Figure 6b); the distance between the clamp and the couplet should be equal to the cavity width of the wall (80 mm).

Figure 4 – Scheme of the test apparatus.

1_{In brackets the reference to the numbers in the drawings Figure 4 and Figure 5.}

2_{The threaded bars are interrupted in}Figure 5_{to provide a more understandable view of the support system of the}

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Version 01 - Final 04/01/2017 Figure 5 – Detail of the support system of the couplets.

(a) (b)

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Version 01 - Final 04/01/2017 Instrumentation

A couple of linear potentiometers is installed symmetrically on the two opposite sides of the clamp, pointing against the horizontal steel plate; the linear potentiometers measure the displacement of the couplet with respect to the clamp, in accordance with NEN 846-5:201 [4]. Their measuring range is 100 mm with an accuracy of 1.0% (that can be significantly reduced after calibration).

The instrumentation scheme is displayed in Figure 7.

(a) (b)

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Version 01 - Final 04/01/2017 Loading scheme

The test is completed in accordance with EN 846-5:2012.

The specimen is placed in the test machine such that the tie body is axial and aligned at the center of the test machine. The tie is clamped so that it has a free distance from the couplet equal to 80 mm.

The specimen is kept under constant lateral pre-compression, while an axial load is applied to the tie. Two levels of precompression are investigated (0.1 ± 0.01 N/mm2_{and 0.3 ± 0.01 N/mm}2₎3_.

The axial load is applied in displacement control while the precompressive load is maintained constant by means of the manually operated hydraulic jack. Three different loading schemes are followed:

 Protocol A1 (monotonic tensile protocol): the pull-out behavior of the ties (tensile loading) is determined by monotonically increasing the displacement with a rate of 0.1 mm/s up to failure.  Protocol A2 (monotonic compressive protocol): the compressive axial behavior of the ties

(compressive loading) will be determined by monotonically increasing the displacement with a rate of 0.1mm/s.

 Protocol A3 (tensile-compressive protocol): the displacement is cyclically varied by applying both tensile and compressive loads on the tie. The loading history for this test can be subdivided into two phases. In phase 1 three groups of three cycles of amplitude equal to 0.1 mm, 0.25 mm and 0.5 mm, respectively, are performed. In phase 2 each cycle is composed by two runs of increased displacements and two runs of reduced displacement. The reduced displacements are calculated as the 40% of the displacements of the two previous runs (Figure 8). The loading rate is chosen to maintain a constant duration of every cycle until reaching 1 mm/s. Afterwards it is kept constant.

Figure 8 - Loading protocol 3 (cyclic protocol).

The name and number of the specimens tested for each loading protocol (for the axial tests) are listed in Table 2. The number of planned tests differs significantly from typology to typology in order to integrate the tests performed during the campaign of 2015 [3] and have a similar total number of tests.

3_{A single level of precompression for the same specimen typologies was applied during the tests of the experimental}

campaign of 2015 [3]. -6 -4 -2 0 2 4 6 0 1 2 3 4 5 6 V e rt ic a l d is p la c e m e n t [m m ] Group of cycles Phase 1 Phase 2 Phase 2-continues

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Version 01 - Final 04/01/2017 Table 2 – Specimens tested for each loading protocol for axial loads

Name Bricks Loading protocol _pressureLateral

Performed tests 2015 2016 Total TUD_ANC-11 Calcium Silicate Protocol A1 (monotonic tension) 0.1 MPa 6 0 6 0.3 MPa 3 10 13 TUD_ANC-12 Protocol A2 (monotonic compression) 0.1 MPa 0 8 8 0.3 MPa 7 2 9 TUD_ANC-13 Protocol A3 (cyclic) 0.1 MPa 0 10 10 0.3 MPa 8 0 8 TUD_ANC-21 Clay Protocol A1 (monotonic tension) 0.1 MPa 3 4 7 0.3 MPa 4 6 10 TUD_ANC-22 Protocol A2 (monotonic compression) 0.1 MPa 0 6 6 0.3 MPa 3 3 6 TUD_ANC-23 Protocol A3 (cyclic) 0.1 MPa 0 10 10 0.3 MPa 8 0 8

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Experimental results on TUD_ANC-1i specimens (calcium

silicate masonry)

Monotonic tensile tests – TUD_ANC-11

The observed failure mechanisms showed cracking and crushing of the mortar and strengthening of the steel tie for tensile loadings (Figure 9).

(a) (b)

Figure 9 – Failure mechanism of wall ties embedded in calcium silicate couplets for tensile loadings.

Precompression level: 0.1 ± 0.01 N/mm2

A sufficient number of specimens were tested at such precompression level during the campaign of 2015, therefore no specimens were tested in this campaign under such conditions. However, for the sake of completeness, the results of the previously conducted tests will also be presented in this section. Table 3 and Figure 10 report the force-displacement curves for each single performed test and a summary of the results.

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Version 01 - Final 04/01/2017 Figure 10 – Summary of the “Force-Displacement curves” for monotonic tensile loading of calcium silicate

specimens at a level of precompression 0.1MPa (2015)

Table 3 – Summary of results for monotonic tensile loading of calcium silicate specimens at a level of precompression 0.1MPa (2015)

Specimen Peak vertical force [kN] Displacement [mm]

TUD-MAT-17A 1.29 10.63 TUD-MAT-17B 1.22 10.06 TUD-MAT-17C 1.33 10.06 TUD-MAT-17D 1.17 12.84 TUD-MAT-17E 1.36 7.69 TUD-MAT-17F 1.10 9.96 Average 1.25 10.21 Standard deviation 0.10 1.65 Coefficient of variation 8% 16% 0 0.2 0.4 0.6 0.8 1 1.2 1.4 0 5 10 15 20 25 30 35 40 V e rt ic al f o rc e [ kN ] Vertical displacement [mm] TUD-MAT-17A TUD-MAT-17B TUD-MAT-17C TUD-MAT-17D TUD-MAT-17E TUD-MAT-17F Average-0.1MPa

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Figure 11, Figure 12 and Table 4 report the force-displacement curves for each single performed test and a summary of the results.

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0 10 20 30 40 50 P u ll -o u t fo rc e ( k N ) Pull-out displacement (mm) TUD_ANC-11-01 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0 10 20 30 40 50 P u ll -o u t fo rc e ( k N ) Pull-out displacement (mm) TUD_ANC-11-02 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0 10 20 30 40 50 P u ll -o u t fo rc e ( k N ) Pull-out displacement (mm) TUD_ANC-11-03 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0 10 20 30 40 50 P u ll -o u t fo rc e ( k N ) Pull-out displacement (mm) TUD_ANC-11-07 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0 10 20 30 40 50 P u ll -o u t fo rc e ( k N ) Pull-out displacement (mm) TUD_ANC-11-10 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0 10 20 30 40 50 P u ll -o u t fo rc e ( k N ) Pull-out displacement (mm) TUD_ANC-11-11

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Version 01 - Final 04/01/2017 Figure 11 – Force displacement curve for monotonic tensile loading of calcium silicate specimens at a level

of precompression 0.3MPa (2016)

Figure 12 – Summary of the “Force-Displacement curves” for monotonic tensile loading of calcium silicate specimens at a level of precompression 0.3MPa (2016)

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0 10 20 30 40 50 P u ll -o u t fo rc e ( k N ) Pull-out displacement (mm) TUD_ANC-11-12 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0 10 20 30 40 50 P u ll -o u t fo rc e ( k N ) Pull-out displacement (mm) TUD_ANC-11-13 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0 10 20 30 40 50 P u ll -o u t fo rc e ( k N ) Pull-out displacement (mm) TUD_ANC-11-16 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0 10 20 30 40 50 P u ll -o u t fo rc e ( k N ) Pull-out displacement (mm) TUD_ANC-11-17

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Version 01 - Final 04/01/2017 Table 4 – Summary of results for monotonic tensile loading of calcium silicate specimens at a level of

precompression 0.3MPa (2016)

TUD_ANC-11-01 1.21 8.54 TUD_ANC-11-02 1.33 8.93 TUD_ANC-11-03 1.13 9.60 TUD_ANC-11-07 1.35 8.39 TUD_ANC-11-10 1.35 7.24 TUD_ANC-11-11 1.29 7.49 TUD_ANC-11-12 1.34 8.67 TUD_ANC-11-13 1.50 8.26 TUD_ANC-11-16 1.27 7.57 TUD_ANC-11-17 1.40 9.79 Average 1.32 8.45 Standard deviation 0.10 0.86 Coefficient of variation 8% 10% Tests performed in 2015

The results obtained during the testing campaign of 2015, reported in [3], are hereafter summarised by Figure 13 and Table 5. A similar failure mode to that presented in Figure 9 was observed (Figure 14).

Figure 13 – Summary of the “Force-Displacement curves” for monotonic tensile loading of calcium silicate specimens at a level of precompression 0.3MPa (2015)

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(a) (b)

Figure 14. Crack pattern of specimen TUD_MAT-17b tested under monotonic tensile loading at failure (testing campaign 2015).

Table 5 – Summary of results for monotonic tensile loading of calcium silicate specimens at a level of precompression 0.3MPa (2015)

TUD-MAT-17c 1.51 7.86 TUD-MAT-17b 1.57 8.12 TUD-MAT-17d 1.11 9.28 Average 1.40 8.42 Standard deviation 0.25 0.76 Coefficient of variation 18% 9% Tests 2015/2016

The results of the testing campaign 2015 and 2016 are summarised in Figure 15 and Table 6.

The results are similar during the two campaigns, even though smaller dispersion is obtained during the current campaign.

Table 6 – Average results for monotonic tension of CS specimens

Campaign Peak vertical force [kN] Displacement [mm]

2015 1.32 8.45

2016 1.40 8.42

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Version 01 - Final 04/01/2017 Figure 15 – Comparison of force displacement curves for monotonic tensile loading of calcium silicate

specimens at a level of precompression 0.3MPa for campaigns of 2015 and 2016

Influence of the level of precompression

Taking into account the average curve for each level of precompression (considering both campaigns), it can be determined whether the level of precompression plays a significant role in the behaviour of the specimens. The following figures (Figure 16, Figure 17) indicate that the influence of the level of precompression is insignificant as the peak vertical force and the corresponding displacement are similar and the individual curves of the specimens for different precompression levels overlap (Table 7).

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Version 01 - Final 04/01/2017 Figure 17 – Average curves of vertical force vs. displacement for the two different levels of precompression Table 7 – Peak vertical force and corresponding displacement for the two levels of precompression

Precompression [MPa] Peak vertical force [kN] Displacement [mm]

0.1 1.25 10.21

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Version 01 - Final 04/01/2017 Monotonic compressive tests – TUD_ANC-12

Independently of the applied precompression level, the same failure mechanism was observed, with piercing and expulsion of the cone of mortar next to the embedded steel tie for compressive loadings (Figure 18).

(a) (b)

Figure 18 – Failure mechanism of wall ties embedded in calcium silicate couplets for compression loadings.

Figure 19 and Figure 20 report the force-displacement curves for each single performed test and a summary of the results. A rather brittle post-peak behaviour is observed. For large displacements (>40 mm), the compressive strength increases significantly after that the zig-zag portion of the tie pierces the mortar. 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0 20 40 60 80 P u ll -o u t fo rc e ( k N ) Pull-out displacement (mm) TUD_ANC-12-18 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0 20 40 60 80 P u ll -o u t fo rc e ( k N ) Pull-out displacement (mm) TUD_ANC-12-19 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0 20 40 60 80 P u ll -o u t fo rc e ( k N ) Pull-out displacement (mm) TUD_ANC-12-20 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0 20 40 60 80 P u ll -o u t fo rc e ( k N ) Pull-out displacement (mm) TUD_ANC-12-57

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Version 01 - Final 04/01/2017 Figure 19 – Force displacement curve for monotonic compressive loading of calcium silicate specimens at a

level of precompression 0.1MPa (2016)

Figure 20 – Summary of the “Force-Displacement curves” for monotonic compressive loading of calcium silicate specimens at a level of precompression 0.1MPa (2016)

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0 20 40 60 80 P u ll -o u t fo rc e ( k N ) Pull-out displacement (mm) TUD_ANC-12-58 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0 20 40 60 80 P u ll -o u t fo rc e ( k N ) Pull-out displacement (mm) TUD_ANC-12-71 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0 20 40 60 80 P u ll -o u t fo rc e ( k N ) Pull-out displacement (mm) TUD_ANC-12-73 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0 20 40 60 80 P u ll -o u t fo rc e ( k N ) Pull-out displacement (mm) TUD_ANC-12-74

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Version 01 - Final 04/01/2017 Table 8 – Summary of results for monotonic compressive loading of calcium silicate specimens at a level of

TUD_ANC-12-18 1.08 1.54 TUD_ANC-12-19 1.36 2.79 TUD_ANC-12-20 1.41 2.58 TUD_ANC-12-57 1.08 1.14 TUD_ANC-12-58 1.22 2.08 TUD_ANC-12-74 0.78 0.96 TUD_ANC-12-73 1.00 2.12 TUD_ANC-12-71 1.08 2.74 Average 1.13 1.99 Standard deviation 0.19 0.67 Coefficient of variation 17% 34%

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Figure 21 and Figure 22 report the force-displacement curves for each single performed test and a summary of the results. The observed results are similar to those obtained for the lower precompression level.

Figure 21 – Force displacement curve for monotonic compressive loading of calcium silicate specimens at a level of precompression 0.3MPa (2016)

Table 9 – Summary of results for monotonic compressive loading of calcium silicate specimens at a level of precompression 0.3MPa (2016)

TUD_ANC-12-09 1.33 3.40 TUD_ANC-12-72 1.02 1.90 Average 1.17 2.65 Standard deviation 0.15 0.75 Coefficient of variation 13% 28% 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0 20 40 60 80 P u ll -o u t fo rc e ( k N ) Pull-out displacement (mm) TUD_ANC-12-09 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0 20 40 60 80 P u ll -o u t fo rc e ( k N ) Pull-out displacement (mm) TUD_ANC-12-72

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Tests performed in 2015

The results obtained during the campaign of 2015, reported in [3], are hereafter summarised. Also in compression the failure mode is similar to that presented in Figure 18, as shown in Figure 24.

Table 10 – Summary of results for monotonic compressive loading of calcium silicate specimens at a level of precompression 0.3MPa (2015)

TUD_MAT-17o 1.54 2.26 TUD_MAT-17p 0.81 0.52 TUD_MAT-17q 1.68 0.38 TUD_MAT-17r 1.72 1.02 TUD_MAT-17ac 0.83 0.35 TUD_MAT-17ad 1.37 1.66 Average 0.99 1.03 Standard deviation 0.37 0.78 Coefficient of variation 37% 76%

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Tests 2015/2016

The results of the testing campaign 2015 and 2016 are summarised in Figure 25 and Figure 10.

The two tests performed in 2016 are in line with those of the previous campaign, even though a larger resistance is measured.

Figure 25 – Comparison of force displacement curves for monotonic compressive loading of calcium silicate specimens at a level of precompression 0.3MPa for campaigns of 2015 and 2016

Table 11 – Average results for monotonic compression of CS specimens

2015 0.99 1.03

2016 1.17 2.65

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Influence of the level of precompression

Figure 26, Figure 27 and Table 12 show that the influence of the level of precompression is not significant, as the peak vertical force and the corresponding displacement are similar.

Figure 26 – Collective results for the two different levels of precompression

Figure 27 – Average curves of vertical force vs. displacement for the two different levels of precompression Table 12 – Peak vertical force and corresponding displacement for the two levels of precompression

0.1 1.13 1.99

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Version 01 - Final 04/01/2017 Cyclic tests – TUD_ANC-13

The observed failure mode of the specimens is a combination of those described in sections 3.2.1 and 3.2.2 for tensile and compressive loading, respectively.

Figure 28 reports the force-displacement curves for each single performed test and a summary of the results. Figure 29 shows an example of how an envelope curve is derived; Figure 30 and Figure 31 show a summary of every envelope curve for tensile and compressive loading, respectively.

-2 -1.5 -1 -0.5 0 0.5 1 1.5 -60 -40 -20 0 20 40 60 P ul l-o ut fo rce (k N ) Pull-out displacement (mm) TUD_ANC-13-08 -1.5 -1 -0.5 0 0.5 1 1.5 -60 -40 -20 0 20 40 60 P ul l-o ut fo rce (k N ) Pull-out displacement (mm) TUD_ANC-13-60 -1 -0.5 0 0.5 1 1.5 -60 -40 -20 0 20 40 60 P ul l-o ut fo rce (k N ) Pull-out displacement (mm) TUD_ANC-13-67 -1.5 -1 -0.5 0 0.5 1 1.5 -60 -40 -20 0 20 40 60 P ul l-o ut fo rce (k N ) Pull-out displacement (mm) TUD_ANC-13-87 -1.5 -1 -0.5 0 0.5 1 1.5 -60 -40 -20 0 20 40 60 P ul l-o ut fo rce (k N ) Pull-out displacement (mm) TUD_ANC-13-70 -1.5 -1 -0.5 0 0.5 1 1.5 -60 -40 -20 0 20 40 60 P ul l-o ut fo rce (k N ) Pull-out displacement (mm) TUD_ANC-13-65

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Version 01 - Final 04/01/2017 Figure 28 – Force displacement curve for monotonic cyclic loading of calcium silicate specimens at a level of

Figure 29 – Indicative hysteretic curve of a CS specimen under axial cyclic loading at a precompression level of 0.1MPa -1.5 -1 -0.5 0 0.5 1 1.5 -60 -40 -20 0 20 40 60 P ul l-o ut fo rce (k N ) Pull-out displacement (mm) TUD_ANC-13-68 -1.5 -1 -0.5 0 0.5 1 1.5 -60 -40 -20 0 20 40 60 P ul l-o ut fo rce (k N ) Pull-out displacement (mm) TUD_ANC-13-62 -1.5 -1 -0.5 0 0.5 1 1.5 -60 -40 -20 0 20 40 60 P ul l-o ut fo rce (k N ) Pull-out displacement (mm) TUD_ANC-13-64 -1.5 -1 -0.5 0 0.5 1 1.5 -60 -40 -20 0 20 40 60 P ul l-o ut fo rce (k N ) Pull-out displacement (mm) TUD_ANC-13-66

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Version 01 - Final 04/01/2017 Figure 30 – Envelope tension curves of a CS specimens under axial cyclic loading at a precompression level

of 0.1MPa(2016)

Figure 31 – Envelope compression curves of CS specimens under axial cyclic loading at a precompression level of 0.1MPa (2016)

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Version 01 - Final 04/01/2017 Table 13 – Summary of results for cyclic loading of calcium silicate specimens at a level of precompression

0.1MPa (2016)

Specimen

Tension Compression

Peak vertical

force [kN] Displacement [mm] Peak vertical force [kN] Displacement [mm]

TUD_ANC-13-08 1.33 4.82 1.7 4.81 TUD_ANC-13-60 1.09 4.58 1.02 3.56 TUD_ANC-13-67 1.03 4.87 0.84 2.50 TUD_ANC-13-87 1.04 4.75 1.06 4.26 TUD_ANC-13-70 1.27 4.77 0.99 2.50 TUD_ANC-13-65 0.89 4.61 1.31 4.80 TUD_ANC-13-68 0.83 9.91 0.74 2.13 TUD_ANC-13-62 1.04 4.87 0.84 2.50 TUD_ANC-13-66 1 4.74 0.92 3.6 Average 1.09 5.61 1.05 3.41 Standard deviation 0.16 1.76 0.28 0.99 Coefficient of variation 15% 31% 27% 29%

Table 14 – Average peak vertical force and corresponding displacement for cyclic tension and compression

Type of loading Peak vertical force [kN] Displacement [mm]

Tension 1.09 5.61

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Tests 2015

The results obtained during the experimental campaign of 2015, reported in [3], are summarised in Figure 32 and Table 15.

(a) (b)

Figure 32 – Force-slip curves for ties embedded in calcium silicate masonry specimens subject to cyclic test at a precompression level of 0.3MPa (2015): example of a single curve (a) and envelope curves (b). Table 15 – Summary of results for cyclic loading of calcium silicate specimens at a level of precompression

0.3MPa (2015)

Specimen

Peak vertical

TUD_MAT-17n 1.17 14.86 -0.40 -0.39 TUD_MAT-17t 0.92 29.75 -0.49 -0.48 TUD_MAT-17v 1.29 - -0.65 -1.73 TUD_MAT-17z 0.97 4.96 -0.14 -0.87 TUD_MAT-17w 0.94 4.98 -0.09 -0.79 TUD_MAT-17x 0.93 9.88 -0.50 -0.69 TUD_MAT-17y 0.87 9.87 -0.39 -0.98 TUD_MAT-17aa 1.08 28.64 -0.18 -0.67 TUD_MAT-17n 1.17 14.86 -0.40 -0.39 Average 1.02 14.73 -0.36 -0.83 Standard deviation 0.15 8.54 0.20 0.41 Coefficient of variation 14% 58% 55% 50%

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Influence of level of precompression

As shown by the results summarised in Table 16 for specimens tested under cyclic loading, the level of precompression:

- does not affect significantly the tensile resistance of the connection, whereas a lower compressive resistance for higher lateral precompression is obtained;

- determines an increase of the displacement at peak for tensile loads but a reduction for compressive loads.

Therefore, no clear dependence of the results on the lateral constant precompression is observed. Table 16 – Peak vertical force and corresponding displacement for the two levels of precompression for

cyclic loading Precompression [MPa] Tension Compression Peak vertical force [kN] Displacement [mm] Peak vertical force [kN] Displacement [mm] 0.1 1.09 (±0.16) 5.61 (±1.76) 1.05 (±0.28) 3.41 (±0.99) 0.3 1.02 (±0.15) 14.73 (±8.54) 0.36 (±0.20) 0.83 (±0.41)

Summary of the results

The axial strength for tensile and compressive forces for each different loading condition is summarised in Table 17.

The following remarks are reported:

i. The tensile axial strength of the connection is not significantly dependent neither on the applied precompression, nor on the type of loading protocol (monotonic/cyclic), since small difference is observed for the different groups of tests.

ii. The compressive axial strength of the connection is lightly smaller than the tensile resistance; again, small differences are observed depending on the precompression and the loading protocol, except for the cyclic loading at 0.3 MPa precompression, for which a significantly lower resistance was measured.

iii. The values of the displacements at peak vary considerably from test to test; however,

displacements at peak equal to 10 mm for tensile loading and 2 mm for compressive loading can be considered reasonable reference values.

iv. No significant difference were observed between the results of the same typology of tests performed during the testing campaign of 2015 and 2016.

Table 17 – Summary of the results for axial tests for Calcium Silicate specimens. Type

of bricks

Loading

protocol Precompression level

Axial strength Displacement at peak

Tensile Compressive Tensile Compressive

Calcium Silicate Monotonic 0.1 MPa 1.25 kN -1.13 kN 10.21 mm -1.99 mm 0.3 MPa 1.34 kN -1.04 kN 8.44 mm -1.44 mm Cyclic 0.1 MPa 1.09 kN -1.05 kN 5.61 mm -3.41 mm 0.3 MPa 1.02 kN -0.36 kN 14.73 mm -0.83 mm

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Experimental results on TUD_ANC-2j specimens (clay masonry)

Monotonic tensile tests – TUD_ANC-21

Independently of the applied precompression level, the same failure mechanism was observed, with failure of the mortar and dowel effect from the mortar in the holes (Figure 33).

Figure 33 – Failure mechanism of wall ties embedded in clay couplets for tensile loadings.

Figure 34 and Figure 35 report the force-displacement curves for each single performed test and a summary of the results.

Figure 34 – Force displacement curve for monotonic tensile loading of clay specimens at a level of precompression 0.1MPa (2016) 0 0.5 1 1.5 2 2.5 0 5 10 15 20 P u ll -o u t fo rc e (k N ) Pull-out displacement (mm) TUD_ANC-21-09 0 0.5 1 1.5 2 2.5 0 5 10 15 20 P u ll -o u t fo rc e (k N ) Pull-out displacement (mm) TUD_ANC-21-10 0 0.5 1 1.5 2 2.5 0 5 10 15 20 P u ll -o u t fo rc e (k N ) Pull-out displacement (mm) TUD_ANC-21-13 0 0.5 1 1.5 2 2.5 0 5 10 15 20 P u ll -o u t fo rc e (k N ) Pull-out displacement (mm) TUD_ANC-21-17

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Version 01 - Final 04/01/2017 Figure 35 – Summary of the “Force-Displacement curves” for monotonic tensile loading of clay specimens at

a level of precompression 0.1MPa (2016)

Table 18 – Summary of results for monotonic tensile loading of clay specimens at a level of precompression 0.1MPa (2016)

TUD_ANC-21-09 1.96 1.00 TUD_ANC-21-10 2.14 0.71 TUD_ANC-21-13 2.16 1.05 TUD_ANC-21-17 1.40 0.79 Average 1.92 0.89 Standard deviation 0.35 0.16 Coefficient of variation 19% 18% Tests 2015

TUD_MAT-27a 2.03 3.70 TUD_MAT-27b 2.30 4.81 TUD_MAT-27e 1.59 2.96 Average 1.97 3.82 Standard deviation 0.29 0.76 Coefficient of variation 0.15 0.20

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Tests 2015/2016

The tests performed in 2016 have similar peak strength of those of the previous campaign, even though a smaller displacement at peak is measured.

Figure 37 – Comparison of force displacement curves for monotonic tensile loading of clay specimens at a level of precompression 0.1MPa for campaigns of 2015 and 2016

0 0.5 1 1.5 2 2.5 0 5 10 15 20 25 V er ti ca l fo rc e [k N ] Vertical displacement [mm] TUD_MAT_27a TUD_MAT_27b TUD_MAT_27e Average-0.1MPa 0 0.5 1 1.5 2 2.5 0 5 10 15 20 V er ti ca l f o rc e [k N ] Vertical displacement [mm] 2015 2016 Average-2015 Average-2016 Average-0.1MPa

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Version 01 - Final 04/01/2017 Table 20 – Average results for monotonic tension of clay specimens

2015 1.97 3.82

2016 1.92 0.89

Weighted Average 1.94 2.14

Figure 38 and Figure 39 report the force-displacement curves for each single performed test and a summary of the results. The post-peak behavior is more brittle than for calcium silicate specimens.

Figure 38 – Force displacement curve for monotonic tensile loading of clay specimens at a level of precompression 0.3MPa (2016) 0 0.5 1 1.5 2 2.5 0 5 10 15 20 P u ll -o u t fo rc e ( k N ) Pull-out displacement (mm) TUD_ANC-21-07 0 0.5 1 1.5 2 2.5 0 5 10 15 20 P u ll -o u t fo rc e ( k N ) Pull-out displacement (mm) TUD_ANC-21-08 0 0.5 1 1.5 2 2.5 0 5 10 15 20 P u ll -o u t fo rc e ( k N ) Pull-out displacement (mm) TUD_ANC-21-18 0 0.5 1 1.5 2 2.5 0 5 10 15 20 P u ll -o u t fo rc e ( k N ) Pull-out displacement (mm) TUD_ANC-21-21

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TUD_ANC-21-07 1.11 0.55 TUD_ANC-21-08 0.89 0.67 TUD_ANC-21-18 2.14 1.63 TUD_ANC-21-21 2.24 1.84 Average 1.60 1.17 Standard deviation 0.69 0.66 Coefficient of variation 44% 56% Tests 2015

TUD_MAT-27a 2.58 5.34 TUD_MAT-27b 3.39 7.08 TUD_MAT-27c 2.38 3.28 TUD_MAT-27m 2.68 6.01 Average 2.76 5.43 Standard deviation 0.44 1.60 Coefficient of variation 16% 29%

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Tests 2015/2016

The tests performed in 2016 have reuced peak strength and displacement at peak of those of the previous campaign.

Figure 41 – Comparison of force displacement curves for monotonic tensile loading of clay specimens at a level of precompression 0.3MPa for campaigns of 2015 and 2016

0 0.5 1 1.5 2 2.5 3 3.5 0 5 10 15 20 25 30 35 V e rt ic al f or ce [ kN ] Vertical displacement [mm] TUD_MAT_27a TUD_MAT_27b TUD_MAT_27c TUD_MAT_27m Average-0.3MPa 0 0.5 1 1.5 2 2.5 3 3.5 0 5 10 15 20 25 V e rt ic al f or ce [ kN ] Vertical displacement [mm] 2015 2016 Average-2015 Average-2016 Average-0.3MPa

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Version 01 - Final 04/01/2017 Table 23 – Average results for monotonic tension of clay specimens

2015 2.76 5.43

2016 1.60 1.17

As shown by the results summarised in Figure 42 and Table 24 for specimens tested under cyclic loading, the level of precompression:

- Does not affects neither the tensile nor the compressive resistance of the connection; - Does not affects the displacement at peak for either tensile or compressive loads. Therefore, no clear dependence of the results on the lateral constant precompression is observed.

Figure 42 – Collective results for the two different levels of precompression Table 24 – Peak vertical force and corresponding displacement for the two levels of precompression

0.1 2.34 3.36 0.3 2.18 3.30 0 0.5 1 1.5 2 2.5 3 3.5 0 5 10 15 20 25 V e rt ic al f or ce [ kN ] Vertical displacement [mm] 0.1MPa 0.3MPa Average-0.1MPa Average-0.3MPa

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Version 01 - Final 04/01/2017 Monotonic compressive tests – TUD_ANC-22

Independently of the applied precompression level, the same failure mechanism was observed, with buckling of the steel tie (Figure 43).

(a) (b)

Figure 43 – Failure mechanism of wall ties embedded in clay couplets for tensile loadings.

Figure 44, Figure 45 and Table 25 report the force-displacement curves for each single performed test and a summary of the results. The post-peak behavior is more brittle than for calcium silicate specimens.

0 0.5 1 1.5 2 2.5 0 5 10 15 20 25 P u ll -o u t fo rc e ( k N ) Pull-out displacement (mm) TUD_ANC-22-14 0 0.5 1 1.5 2 2.5 0 5 10 15 20 25 P u ll -o u t fo rc e ( k N ) Pull-out displacement (mm) TUD_ANC-22-14 0 0.5 1 1.5 2 2.5 0 5 10 15 20 25 P u ll -o u t fo rc e ( k N ) Pull-out displacement (mm) TUD_ANC-22-26 0 0.5 1 1.5 2 2.5 0 5 10 15 20 25 P u ll -o u t fo rc e ( k N ) Pull-out displacement (mm) TUD_ANC-22-30

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Version 01 - Final 04/01/2017 Figure 44 – Force displacement curve for monotonic compressive loading of clay specimens at a level of

Figure 45 – Summary of the “Force-Displacement curves” for monotonic compressive loading of clay specimens at a level of precompression 0.1MPa (2016)

0 0.5 1 1.5 2 2.5 0 5 10 15 20 25 P u ll -o u t fo rc e ( k N ) Pull-out displacement (mm) TUD_ANC-22-33 0 0.5 1 1.5 2 2.5 0 5 10 15 20 25 P u ll -o u t fo rc e ( k N ) Pull-out displacement (mm) TUD_ANC-22-34 0 0.5 1 1.5 2 2.5 0 5 10 15 20 25 P u ll -o u t fo rc e ( k N ) Pull-out displacement (mm) TUD_ANC-22-35

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Version 01 - Final 04/01/2017 Table 25 – Summary of results for monotonic compressive loading of clay specimens at a level of

TUD_ANC-22-14 1.76 1.98 TUD_ANC-22-25 1.89 1.34 TUD_ANC-22-26 1.21 2.11 TUD_ANC-22-30 1.97 1.24 TUD_ANC-22-33 1.77 2.65 TUD_ANC-22-34 2.08 1.36 TUD_ANC-22-35 1.80 1.14 Average 1.78 1.69 Standard deviation 0.28 0.57 Coefficient of variation 16% 33% Precompression level: 0.3 ± 0.01 N/mm2

Figure 46, Figure 47 and Table 26 report the force-displacement curves for each single performed test and a summary of the results. The observed results are similar to those obtained for the lower precompression level.

Figure 46 – Force displacement curve for monotonic compressive loading of clay specimens at a level of precompression 0.3MPa (2016) 0 0.5 1 1.5 2 2.5 0 5 10 15 20 25 P u ll -o u t fo rc e ( k N ) Pull-out displacement (mm) TUD_ANC-22-27 0 0.5 1 1.5 2 2.5 0 5 10 15 20 25 P u ll -o u t fo rc e ( k N ) Pull-out displacement (mm) TUD_ANC-22-29 0 0.5 1 1.5 2 2.5 0 5 10 15 20 25 P u ll -o u t fo rc e ( k N ) Pull-out displacement (mm) TUD_ANC-22-31

(43)

Version 01 - Final 04/01/2017 Figure 47 – Summary of the “Force-Displacement curves” for monotonic compressive loading of clay

specimens at a level of precompression 0.3MPa (2016)

Table 26 – Summary of results for monotonic compressive loading of clay specimens at a level of precompression 0.3MPa (2016)

TUD_ANC-22-27 1.62 2.22 TUD_ANC-22-29 1.29 2.21 TUD_ANC-22-31 2.16 0.98 Average 1.69 1.80 Standard deviation 0.44 0.71 Coefficient of variation 26% 40% Tests 2015

The results obtained during the experimental campaign of 2015, reported in [3], are summarised in Table 27 and Figure 48.

Table 27 – Summary of results for monotonic compressive loading of clay specimens at a level of precompression 0.3MPa (2015)

TUD_MAT-27d 1.97 1.34 TUD_MAT-27e 1.83 0.95 TUD_MAT-27f 1.68 1.34 Average 1.83 1.21 Standard deviation 0.14 0.23 Coefficient of variation 0.08 0.19

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Figure 48 – Summary of the “Force-Displacement curves” for monotonic compressive loading of clay specimens at a level of precompression 0.3MPa (2015)

Tests 2015/2016

The tests performed in 2016 have reuced peak strength and displacement at peak of those of the previous campaign.

Figure 49 – Comparison of force displacement curves for monotonic compressive loading of clay specimens at a level of precompression 0.3MPa for campaigns of 2015 and 2016

0 0.5 1 1.5 2 2.5 0 5 10 15 20 V e rt ic al f or ce [ kN ] Vertical displacement [mm] TUD_MAT-27d TUD_MAT-27e TUD_MAT-27f Average-2015 0 0.5 1 1.5 2 2.5 0 5 10 15 20 25 V e rt ic al f or ce [ kN ] Vertical displacement [mm] 2015 2016 Average-2015 Average-2016 Average-0.3MPa

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Version 01 - Final 04/01/2017 Table 28 – Average results for monotonic compression of clay specimens

2015 1.67 1.34

2016 1.50 0.98

- Does not affects neither the tensile nor the compressive resistance of the connection; - Does not affects the displacement at peak for either tensile or compressive loads. Therefore, no clear dependence of the results on the lateral constant precompression is observed.

Figure 50 – Collective results for the two different levels of precompression Table 29 – Peak vertical force and corresponding displacement for the two levels of precompression

0.1 1.69 1.80 0.3 1.59 1.16 0 0.5 1 1.5 2 2.5 0 5 10 15 20 25 30 V e rt ic al f or ce [ kN ] Vertical displacement [mm] 0.1MPa 0.3MPa Average-0.1MPa Average-0.3MPa

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Version 01 - Final 04/01/2017 Cyclic tests – TUD_ANC-23

For every specimen the same failure mechanism was observed, with a combination of cracking of the mortar and buckling of the steel tie (Figure 51).

(a) (b)

Figure 51 – Failure mechanism of wall ties embedded in clay couplets for cyclic loadings.

Figure 52 reports the force-displacement curves for each single performed test and a summary of the results. Figure 53 shows an example of how an envelope curve is derived; Figure 54 and Figure 55 show a summary of every envelope curve for tensile and compressive loading, respectively. A quasi-brittle post-peak behavior is observed. -3 -2 -1 0 1 2 3 -30 -20 -10 0 10 20 30 P u ll -o u t fo rc e (k N ) Pull-out displacement (mm) TUD_ANC-23-66 -3 -2 -1 0 1 2 3 -30 -20 -10 0 10 20 30 P u ll -o u t fo rc e (k N ) Pull-out displacement (mm) TUD_ANC-23-39 -3 -2 -1 0 1 2 3 -30 -20 -10 0 10 20 30 P u ll -o u t fo rc e (k N ) Pull-out displacement (mm) TUD_ANC-23-12 -3 -2 -1 0 1 2 3 -30 -20 -10 0 10 20 30 P u ll -o u t fo rc e (k N ) Pull-out displacement (mm) TUD_ANC-23-20

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Version 01 - Final 04/01/2017 Figure 52 – Force displacement curve for monotonic cyclic loading of clay specimens at a level of

Figure 53 – Indicative hysteretic curve of a clay specimen under axial cyclic loading at a precompression level of 0.1MPa (2016) -3 -2 -1 0 1 2 3 -30 -20 -10 0 10 20 30 P u ll -o u t fo rc e (k N ) Pull-out displacement (mm) TUD_ANC-23-78 -3 -2 -1 0 1 2 3 -30 -20 -10 0 10 20 30 P u ll -o u t fo rc e (k N ) Pull-out displacement (mm) TUD_ANC-23-64

-2

-1.5

-1

-0.5

0

0.5

1

1.5

2 -30

-20

-10

0

10

20

30 V

e

rt

ic

al

f

or

ce

[

kN

]

Displacement [mm]

TUD_ANC-23-66

Envelope - Tension

Envelope - Compression

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Version 01 - Final 04/01/2017 Figure 54 – Envelope tension curves of a clay specimens under axial cyclic loading at a precompression level

of 0.1MPa (2016)

Figure 55 – Envelope compression curves of clay specimens under axial cyclic loading at a precompression level of 0.1MPa (2016) 0 0.5 1 1.5 2 2.5 3 0 5 10 15 20 25 Ver tical fo rc e [ kN ] Vertical displacement [mm] Tension Envelope-66 Tension Envelope-39 Tension Envelope-12 Tension-Envelope-20 Tension Envelope-78

Average Tension Envelope-0.1MPa

0 0.5 1 1.5 2 2.5 3 0 5 10 15 20 25 Ver tical fo rc e [ kN ] Vertical displacement [mm] Compression Envelope-66 Compression Envelope-39 Compression Envelope-12 Compression Envelope-20 Compression Envelope-78

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Version 01 - Final 04/01/2017 Table 30 – Summary of results for cyclic loading of clay specimens at a level of precompression 0.1MPa

(2016)

Specimen

Peak vertical

TUD_ANC-23-66 1.8 2.14 1.73 1.83 TUD_ANC-23-39 0.74 2.36 1.21 0.82 TUD_ANC-23-12 2.34 2.37 1.83 0.31 TUD_ANC-23-20 2.27 8.30 1.52 1.81 TUD_ANC-23-78 2.5 2.28 1.9 0.46 TUD_ANC-23-64 1.71 2.00 2.06 2.43 Average 1.89 3.24 1.71 1.28 Standard deviation 0.59 2.27 0.28 0.79 Coefficient of variation 31% 70% 16% 62%

Table 31 – Average peak vertical force and corresponding displacement for cyclic tension and compression

Type of loading Peak vertical force [kN] Displacement [mm]

Tension 1.89 3.24

Compression 1.71 1.28

Tests 2015

(a) (b)

Figure 56 – Force-slip curves for ties embedded in calcium silicate masonry specimens subject to cyclic test at a precompression level of 0.3MPa (2015): example of a single curve (a) and envelope curves (b).

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Version 01 - Final 04/01/2017 Table 32 – Summary of results for cyclic loading of calcium silicate specimens at a level of precompression

0.3MPa (2015)

Specimen

Peak vertical

TUD_MAT-27g 2.30 2.42 -1.40 -1.30 TUD_MAT-27h 3.15 7.31 -1.49 -0.91 TUD_MAT-27i 2.64 4.62 -1.39 -0.96 TUD_MAT-27l 3.28 7.48 -1.38 -0.55 TUD_MAT-27n 3.04 4.89 -1.39 -0.45 TUD_MAT-27o 2.54 1.24 -1.33 -0.44 TUD_MAT-27p 3.69 9.73 -1.55 -0.13 TUD_MAT-27q 3.57 9.30 -1.43 -0.24 Average 3.03 5.87 -1.42 -0.62 Standard deviation 0.50 3.10 0.07 0.40 Coefficient of variation 16% 53% 5% 64%

- affects the tensile resistance of the connection, but not the compressive resistance; - determines a reduction of the displacement at peak for both tensile and compressive loads. Therefore, no clear dependence of the results on the lateral constant precompression is observed.

Table 33 – Peak vertical force and corresponding displacement for the two levels of precompression for cyclic loading

Precompression [MPa]

Peak vertical

0.1 1.89 (±0.59) 3.24 (±2.27) 1.71 (±0.28) 1.28 (±0.79)

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Version 01 - Final 04/01/2017 Summary of the results

The axial strength for tensile and compressive forces for each different loading condition is summarised in Table 34.

The following remarks are reported:

i. The tensile axial strength of the connection is affected by the applied precompression, but a clear dependence cannot be clearly identified. Besides, it is not dependent on the type of loading protocol (monotonic/cyclic), since small difference is observed for the different groups of tests.

ii. The compressive axial strength of the connection is quite constant and does not depend neither on the precompression nor on the loading protocol.

iii. The values of the displacements at peak vary considerably from test to test; however, displacements at peak equal to 3 mm for tensile loading and 1.5 mm for compressive loading can be considered reasonable reference values.

iv. Some differences were observed between the results of the same typology of tests performed during the testing campaign of 2015 and 2016: for the monotonic tensile loading at 0.1 MPa of lateral precompression, for which the displacement at lateral peak varies strongly in the two series (even though the peak load is similar), and at 0.3 MPa, for which also the peak load is significantly different.

Table 34 – Summary of the results for axial tests. Type

of bricks

Loading

protocol Precompression level

Axial strength Displacement at peak

Tensile (kN) Compressive (kN) Tensile (kN) Compressive (kN) Clay Monotonic 0.1 MPa 2.34 (±0.30) 1.69 (±0.28) 3.36 (±1.53) 1.80 (±0.57) 0.3 MPa 2.18 (±0.77) 1.59 (±0.28) _(±2.38)3.30 1.16 (±0.52) Cyclic 0.1 MPa 1.89 (±0.59) 1.71 (±0.28) 3.24 (±2.27) 1.28 (±0.79) 0.3 MPa 3.03 (±0.50) 1.42 (±0.07) 5.87 (±3.10) 0.62 (±0.40)

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4 Shear tests on existing wall ties

Testing procedure

Description of the specimens

L-shaped ties with a diameter of 3.6mm and a length of 200mm will be used; they are produced by Gebr. Bodegraven BV (GB) and are named UNI-L spouwankers 200, 3.6Ø. These ties are the same tested during the experimental campaign of 2015.

The tests refer to cavity walls composed by two masonry walls having each leaf a thickness of approximately 100mm and a cavity space of 80mm. The L-shaped part of the tie is embedded in the inner leaf, which is usually made of calcium silicate masonry or clay masonry, while the zigzag part lies in the outer leaf made of clay masonry. To test a complete connection, two typologies of specimens (with a single tie embedded in the mortar joint of a masonry couplet) are considered:

 Calcium Silicate specimens (TUD_ANC-1i, i = 1, …, 7): hooked part of the tie embedded in a calcium silicate masonry couplet, representing a possible condition for the inner leaf of a cavity wall (anchoring length: 70mm) (Figure 57a);

 Clay specimens (TUD_ANC-2j, j = 1,…,7): Zigzag part of the tie embedded in a clay masonry couplet, representing a possible condition for the inner leaf of a cavity wall (anchoring length: 50mm) (Figure 57b).

(a) (b)

Figure 57 – Tie specimens: Calcium Silicate specimens (TUD_ANC-1i, i = 1, …, 7) (a); Clay specimens (TUD_ANC-2j, j = 1, …, 7) (b).

The dimensions for each typology of specimen are provided in Table 35.

A summary of the properties and the maximum number of planned tests for each typology are presented in Table 36

Table 35 – Dimensions of test specimens.

Dimensions Calcium Silicate specimens _{(TUD_ANC-1i, i = 1, …, 7)} _{(TUD_ANC-2j, j = 1, …, 7)}Clay specimens

ls (mm) 212 210

hs (mm) 152 110

ts (mm) 102 100

ht (mm) 130 150

Test set-up

The test apparatus adopted for shear tests is similar to that used for the axial tests (Section 3.1.2), and it is presented in Figure 58. The only difference is given by the test machine employed to apply the load (3 and 4, in Figure 58.b): the shear tests are performed by applying a vertical load using a displacement controlled

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Version 01 - Final 04/01/2017 apparatus. The apparatus is composed by a 4.5 tons jack (4) and is provided with an extension (3) of the clamp to grip efficiently the free end of the tie (2); the extension of the clamp is designed to transfer rigidly the vertical displacements (which determine shear loads on the tie) and avoid the transversal steel rods (9). The distance between the end of the extension and the couplet is equal to the cavity width of the wall (80 mm).

(a) (b)

(1) Couplet; (2) Tie; (3) Steel extension of the clamp; (4) Clamp; (5) Hydraulic load case and cell; (6) Timber bearers; (7) Vertical steel plates; (8) Existing L-angles; (9) Steel rods.

Figure 58 – Scheme of the test apparatus. Side view (a) and section A-A (b).

(a) (b)

Figure 59 – Test machine (a). Detail of the clamp (b).

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Version 01 - Final 04/01/2017 A couple of linear potentiometers is installed symmetrically on the two opposite sides of the clamp, pointing against the two bricks of the couplet through two additional holes drilled in the plate; the linear potentiometers measure the displacement of the couplet with respect to the clamp, in accordance with NEN 846-5:201. Their measuring range is 100 mm with an accuracy of 1.0% (that can be significantly reduced after calibration). The instrumentation scheme is displayed in Figure 60.

Figure 60 – Employed linear potentiometer scheme.

Loading scheme

The test is completed in accordance with EN 846-5:2012.

The specimen is placed in the test machine such that the tie body is horizontal and aligned at the center of the test machine. The tie is clamped so that it has a free distance from the couplet equal to 80 mm. The specimen is kept under constant lateral pre-compression, while a shear load is applied to the tie. Two levels of pre-compression are investigated (0.1 ± 0.01 N/mm2_{and 0.3 ± 0.01 N/mm}2₎4_.

The shear load is applied in displacement control while the pre-compressive load is maintained constant by means of the manually operated hydraulic jack. Two different loading schemes are followed:

 Protocol S1 (monotonic shear protocol): the shear behavior of the ties is determined by monotonically increasing the displacement with a rate of 0.1mm/s up to failure.

 Protocol S2 (cyclic shear protocol): the displacement is cyclically varied by applying both upward and downward (shear) loads on the tie, as described for Protocol A3 in Section 0 (Axial loading) and is depicted in Figure 61.

The name and number of the specimens tested for each loading protocol (for the shear tests) are listed in Table 36.

4_{A different level of precompression for the same specimen typologies had been tested during the experimental campaign}

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Version 01 - Final 04/01/2017 Figure 61 – Loading protocol S2 (cyclic protocol).

Table 36 – Properties of each tested typology.

Name Bricks Loading protocol Lateral pressure Performed tests

TUD_ANC-14 Calcium Silicate Monotonic 0.1 MPa 2 TUD_ANC-15 0.3MPa 5 TUD_ANC-16 Cyclic 0.1 MPa 3 TUD_ANC-17 0.3 MPa 3 TUD_ANC-24 Clay Monotonic 0.1 MPa 4 TUD_ANC-25 0.3 MPa 4 TUD_ANC-26 Cyclic 0.1 MPa 3 TUD_ANC-27 0.3MPa 3

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Experimental results on TUD_ANC-1X specimens (calcium

silicate masonry)

The performed tests were run according to the procedure above described; however, for large displacements (higher than 20mm), an interaction between axial and shear force occurred due to second order effects. As shown in Figure 62a, when a vertical displacement (dy) is applied the distance between the extremes of the

tie (d) changes; also small horizontal displacements (dx - monitored by an additional sensor) occur because

the loading system is not infinitely stiff and deformations can take place. The increase of the distance d is contrasted by an axial force in the tie, which works as a strut (as reported in the following sections, the shear strength of the connection is almost negligible): the recorded peak load would therefore represent the pullout strength of the tie, and it is not associated to any shear resistance of the connection. For this reason, the shear resistance of the specimen is evaluated as the applied force for a lateral deflection of the tie of 20 mm; at that value of displacement every connection reached a plastic plateau and the second order effects were negligible in most of the cases.

The remaining part of the force displacement curves reported in the following sections is dashed, because the resistance of the connection is affected by its axial resistance.

In principle, the axial force (derived with simple geometrical calculations) can be plot against the extraction length. An example of these graphs is shown in Figure 62b; however, for many specimens the derived plots are not as clear as this one. Besides, for cyclic loading a peak resistance was not achieved.

For these reasons, even though the performed tests can provide useful information they were not planned for this purpose and they should not be used to evaluate directly the interaction between axial and shear forces, and specific tests should be planned.

(a) (b)

Figure 62. Scheme of the displacements of the tie under loading (a) and consequent axial force – extraction length curve for a sample specimen.

0 0.5 1 1.5 2 2.5 0 10 20 30 40 50 60 70 A x ia l fo rce (k N ) Extraction length d (mm) TUD_ANC-17-76

Tests on existing wall ties: shear and axial tests

Tests on existing wall ties: shear and axial tests

Messali, F.; Skroumpelou, G.; Esposito, R.

Publication date

2017

Document Version

Final published version

Citation (APA)

Messali, F., Skroumpelou, G., & Esposito, R. (2017). Tests on existing wall ties: shear and axial tests. Delft

University of Technology.

Important note

To cite this publication, please use the final published version (if applicable).

Please check the document version above.

TU Delft Large-scale testing campaign 2016

TESTS ON EXISTING WALL TIES: SHEAR

AND AXIAL TESTS

Authors: Francesco Messali, Georgia Skroumpelou, Rita Esposito

Table of Contents

1 Introduction

2 Construction of the specimens

3 Axial tests on existing wall ties

Testing procedure

Experimental results on TUD_ANC-1i specimens (calcium

silicate masonry)

Experimental results on TUD_ANC-2j specimens (clay masonry)

-2

-1.5

-1

-0.5

0

0.5

1

1.5

2

-30

-20

-10

0

10

20

30

V

e

rt

ic

al

f

or

ce

[

kN

]

Displacement [mm]

TUD_ANC-23-66

Envelope - Tension

Envelope - Compression

4 Shear tests on existing wall ties

Testing procedure

Experimental results on TUD_ANC-1X specimens (calcium

silicate masonry)