in situ determination of the mechanical performance of the

In situ determination of the mechanical performance of the steel rodsanchored on an existing masonry building wall

ORHAN DOGAN, FATIH CELIK, ORHAN GAZI ODACIOGLU and OZER SEVIM*

Department of Civil Engineering, Kırıkkale University, 71451 Kırıkkale, Turkeye-mail: [email protected]

MS received 10 January 2021; revised 18 July 2021; accepted 23 July 2021

Abstract. In order to strengthen masonry building walls against horizontal earthquake loads, steel plates or

in situ reinforced concrete layers need to be attached to one or both surfaces of the walls. Because the stiffness of

the wall and the stiffness of the strengthening element will be different against earthquake loads, the elastic

connectors are needed to be attached to the strengthening wall to comply with an existing wall. These connectors

must have sufficient and well-known strength, flexibility, spacing, diameter, and depth to resist shear and pull-

out forces that will occur between the wall and the strengthening element. And it is of great importance to

determine the partially interacted pull-out and direct shear performances of the widely known flexible and

commonly used steel rod connectors depending on the diameter and embedment depth in strengthening analysis.

In this study, since the partially interacted pull-out test on chemically anchored steel rods has shown more

realistic failure in comparison to the fully interacted pull-out test and both the partially interacted pull-out test

and the shear test are quite difficult and time-consuming in comparison to the fully interacted pull-out test, the

steel rods were anchored on an existing a five stories masonry building constructed using clay block bricks,

mortar and plaster in Turkey and then three different types of tests were conducted on steel rods to determine the

relation between the fully and partially interacted pull out performances and also between fully interacted pull

out and shear performances. Very significant linear equations were obtained for the shear performance and

partially interacted pull-out performance of the anchor rods in accordance with the fully interacted pull-out

performance of the steel rod connectors for different embedment depth and hole.

Keywords. Clay brick wall; masonry building; earthquake reinforcement in masonry buildings; shear

performance of steel anchor rod; pull-out performance of anchor rods; partially and fully interacted pull-out test

of anchor rods.

1. Introduction

All of Turkey is in a seismic zone. All the historical

buildings and about half of the residences were built as

unreinforced masonry buildings (URM). Although these

buildings are single or several storeys in rural areas, they

are 6-storey in cities [1]. Although the renovation of these

buildings is the most appropriate solution [2], it seems more

economical to retrofit them due to their high number. For

this reason, the most appropriate repair and strengthening

method should be preferred according to the seismic zones,

building material type and mechanical properties, building

characteristic structure and post-earthquake damage [3].

Due to the increased shear force during the earthquake in

URM buildings, out-of-plane toppings and in-plane cracks

and separations are seen, and it is known that the connec-

tion deficiencies between the layers cause these damages

[4]. Anchored connectors are widely used in strengthening

the walls with a rigid diaphragm [5], bonding the wall to the

wall [6], preventing the walls from tipping out of the plane,

bridging the cracks [7], and retrofitting/strengthening the

walls with wooden panels [8], steel strips [9] or concrete

layers [10]. Connectors are exposed to tensile and shear

stresses during earthquakes.

There are many experimental studies on the tensile per-

formance of steel anchors embedded in the walls in liter-

ature by varying the wall materials, anchorage types,

anchorage diameters, embedding depths, and anchorage

area [11–15]. In tensile tests, the application of chemical

anchoring using epoxy to the blind holes drilled for

anchoring to the wall is the most widely used method

besides being efficient [16].

Since the masonry building walls are not homogeneous,

the anchorage tensile strength varies according to the type

of surface material the anchors are attached to. It is known

that anchorages made to the joint areas of the bricks are

more efficient than the other areas of the wall [15]. How-

ever, it is very difficult to direct all the anchors to the joint*For correspondence

Sådhanå (2021) 46:184 � Indian Academy of Sciences

https://doi.org/10.1007/s12046-021-01697-ySadhana(0123456789().,-volV)FT3](0123456789().,-volV)

area because of the closed surfaces of the wall with plaster.

In pull-out tests on masonry walls, bond failures were

observed; at the anchorage-to-interface, at the matrix-to-

substrate interface, at mortar joints due to sliding of bricks,

along a conic surface due to tensile of masonry, at the

anchorage due to tensile failure. While a conical collapse is

observed in anchors with a low buried depth, with the

increase of the embedding depth, yielding failure is

observed in the anchors [17].

There are two different test methods named fully inter-

acted pull-out (Pfi) and partially interacted pull-out (Ppi) for

determining the pull-out capacity of both steel dowel and

chemically bonded steel rods perpendicularly anchored to

concrete. The preferred and commonly used method among

these methods is the pull-out with full interaction test

applied on chemically adhesive anchors, and it occurs in the

form of collapse, breaking of the anchor reinforcement, or

full interaction debonding along the entire anchorage.

Experimental studies have been carried out to find out

the shear performance of the connection connectors that

provide the interaction of masonry walls and reinforcement

elements [18–20]. In anchorages, there is a loss of strength

in the connector area such as tearing in the panel, loss of

strength of the brick, ruptures on the wall surface [8]. It is

recommended to use thin diameter and multiple anchors to

prevent strength losses in brick and masonry [21]. The

ductile behavior of the anchors is of great importance in

terms of the non-linear analysis of an existing masonry

structure and its strengthening elements having different

stiffnesses.

In masonry structures, the external strengthening of the

building emerges as a preferable method, as it will not

disturb the residents in their daily life and is easily appli-

cable (figure 1). However, since the steel rod anchors

between the strengthening RC layer and the existing brick

wall are exposed to extra tensile and shear stresses during

the earthquake, that is why it is of great importance to

determine the material properties of the brick wall before

the strengthening analysis (figure 2).

In this study, it is aimed to determine in situ anchor shear

performance by a simpler pull-out with full interaction,

since the shear test and the pull-out with partial interaction

test are quite difficult and time-consuming. For this pur-

pose, to determine the number of the connectors to be

anchored to the masonry wall surface, an existing building

constructed using traditional commonly used clay bricks

and techniques in the preparation of mortar and plaster in

Ankara/Turkey is chosen as a sample for testing. Here, 2

different experimental set-ups with specially designed,

practical, and useful steel plates were used to determine the

in-situ shear and pull-out with partial interaction of rein-

forcement steel rods with different diameters and embed-

ment depths anchored to the walls of an existing 5-storey

masonry building with clay bricks. Here, 12 pull-outs with

full interaction tests, 24 pull-outs with partial interaction

tests, and 9 shear tests were conducted. Some significant

linear equations were obtained between the shear and pull-

out performances of the anchors depending on the

Figure 1. Models of strengthened masonry building with RC layers.

Figure 2. Model of the strengthened wall with RC layer and

details of steel rod anchors.

184 of 13 Sådhanå (2021) 46:184

embedment depth and anchor diameter. The shear and pull-

out performances of the steel rods anchored on the wall

surface for the strengthening of the masonry walls with clay

bricks, depending on the diameter and anchorage depth,

were determined experimentally. Equations correlating

capacity of pull-out test with partial interaction with

capacity of easier to perform pull-out test with full inter-

action are determined for different anchor diameters and

depths.

2. Experimental Design

The existing masonry building where this study was carried

out was built as 5-storey in the middle of the 20th century.

As a result of the examinations made in the building, it was

seen that it was manufactured with Flemish Bond type

using 2159102965 mm clay bricks. It has been found out

that the thickness of the wall including plaster is 270 mm,

the thickness of the joint mortar is 15-20 mm, and the

thickness of the plaster varies between 20 and 30 mm.

2.1 Experimental set-ups of pull-out testswith partial and full interaction of anchors

The anchorage steel rods were planted chemically on the

wall surface using epoxy (table 1). The steel rods were

inserted in the wall from one face and had different

diameters and embedment depths. The failure modes of the

anchorage steel rods after pull-out with full interaction (Pfi)

and partial interaction (Ppi) tests are given in fig-

ures 3(a) and 3(b), respectively.

In the pull-out with partial interaction test set-up; one

specially designed steel pull-out plate (St 37), one hydraulic

oil pump and one double-acting hydraulic jack, chemical

adhesive, 55 cm long anchor reinforcement rods in Ø10,

Ø12, Ø14, and Ø16 diameters (S420) (figure 4).

Considering that the contribution of the plaster to the

anchorage pull-out strength for the Pfi and Ppi tests is very

small, holes were made on the wall surface by adding ?2

cm plaster thickness to 5, 10, and 15 cm anchorage depths.

For the anchorage depths of 5-15 cm to be applied, bearing

Flemish bonded brick walls of at least 20 cm are preferred.

The holes drilled 5 mm wider than the diameter of the

ribbed anchor reinforcement were cleaned of dust that

caused approximately 70% performance loss with a brush

and air pump. Starting from the farthest point of the holes

drilled for Pfi and Ppi, epoxy is injected so that the space

around the reinforcement is filled completely, and the

reinforcement rods are anchored by punching and/or ham-

mering (figure 5).

The experimental set-up for pull-out tests was prepared

by planting the anchor steel rods of 55 cm length, Ø10,

Ø12, Ø14, and Ø16 at an angle of 90�, into the holes drilled

on the walls. With the help of a hydraulic jack with pull-out

feature (figure 6) and with the help of a designed plate, Ppitests were performed (figure 7).

For Pfi test experiments, 12 anchorage steel rods of four

different diameters (Ø10, Ø12, Ø14 and Ø16) with 5, 10

and 15 cm anchorage depths (Lad) were used. For Ppi test

experiments, 24 anchorage steel rods of four different

diameters (Ø10, Ø12, Ø14 and Ø16) with 5, 10 and 15 cm

anchorage depths (Lad) were used. In drilling for each

anchorage depth 2 cm plaster thickness was added.

While no damage was observed on the wall around the

anchorage steel rods in figure 8(a), in figure 8(b), it was

observed that the conical wall part of varying diameter and

depth came apart depending on the diameter of the rein-

forcement in the Ppi test. It was observed that this conical

early failure which is known as mix type failure observed in

the wall did not contribute to the pull-out capacity of the

anchors, and the pull-out strength of the anchor was

determined by resisting the remaining embedded part with

full stripping. At the end of the Pfi and Ppi experiments, it

was observed that the collapse occurred by debonding at the

epoxy-masonry interface.

2.2 Anchor shear test set-up

To determine the shear performance of the reinforcement

anchors on the wall surface, firstly, Ø10-Ø16 diameter

symmetrical and 4-anchor reinforcement holes were drilled

and an St37 steel ribbed plate was installed. Then, while

creating the experiment set-up; hydraulic oil pump,

hydraulic pressure gauge, hydraulic jack, steel plate, steel

loading plate, ribbed anchor reinforcement rods (S420) in

Ø10, Ø12, and Ø16 diameters, comparator and other sup-

port plates are brought together in a certain order (figures 9

and 10). In addition, as a non-destructive test method, the

N-Schmidt test hammer was used to determine the com-

pressive strength of brick, plaster, and mortar.

To investigate the shear performance of the reinforce-

ment rods anchored to the wall surface under the shear

force applied parallel to the wall surface with the help of a

hydraulic jack, a special steel plate was designed by rein-

forcing it with flats so that there is no tearing and buckling

in the plate, crushing, and breaking in the steel rods.

Hydraulic jack, hydraulic pump, and comparator were

used in the experiment. In the application of loads, 2.5 cm

thick and 20930 cm support plates are used to spread the

stress transferred by the hydraulic jack to the floor, to adjust

Table 1. Mechanical properties and mix proportions of the

epoxy.

Compressive Strength (ASTM 695) [ 56 N/mm2

Flexural Strength (ASTM 790) [ 16 N/mm2

Modulus of Elasticity 3034 N/mm2

Mixture density (20 �C) 1.65 g/cm3

Sådhanå (2021) 46:184 of 13 184

the height, and to fix the magnetic comparator on the

ground and a 191 cm square section 10 cm long steel rod

was used to be placed parallel to the wall surface in order to

transfer the jack load directly to the plate as shear load. As

Figure 3. Experimental test set-ups and collapse modes for a) pull-out with full interaction and b) pull-out with partial interaction.

Figure 4. Pull-out test set-up for rods anchored to the wall.

Figure 5. Attaching pull-out anchors to the flemish bonded brick wall using chemical.

184 of 13 Sådhanå (2021) 46:184

a test sample, ribbed anchor steel rods of 25 cm in length,

Ø10, Ø12 and Ø16 were prepared, 4 for each test. In

addition, a N-Schmidt hammer, one of the non-destructive

test equipment, was used to test the compressive strength of

the brick and plaster mortar separately.

The shear plate is held on the wall surface at a height of

40 cm from the ground, and the anchorage holes are marked

on the wall surface, symmetrical from 4 plate holes for the

same diameters from the loading axis. Considering that the

pull-out force in the anchor steel rods would not cause

collapse, 4 anchor steel rods with the same diameters were

placed in the anchorage holes drilled in the marked places,

without using chemicals, the shear plate was inserted into

the anchor steel rods that were driven at an equal depth to

the wall surface. The hydraulic jack was placed by cen-

tering the ground and the lower surface of the shear plate

parallel to each other, and the lower parts of the hydraulic

jack were supported with steel plates.

The prepared experimental set-up was powered by a

hydraulic jack, and the displacements of the shear plate

were measured together with the applied force. The

experiments continued until 2/3 of the maximum load

decreased after the shear force reached the maximum and

the hydraulic pressure gauge reading was recorded

approximately every 1.00 mm from the loading process

until the test was terminated. Load-displacement graphs

were created with the recorded values. For the shear

capacity of each anchor, the maximum shear force was

found by dividing it into 4, and the elastoplastic behavior

formed by permanent crushes on the wall was obtained.

In the experiments conducted, the anchor steel rods

inside the wall showed a non-linear behavior instead of a

rigid connection due to the weak strength of the wall. The

over-loaded anchor steel rods redistributed their overloads

to the less loaded anchor steel rods. Ensuring the redistri-

bution of the shear forces, the collapse of the steel rods was

prevented (figure 11).

3. Results and Discussions

On the testing walls, the N-Schmidt test which is a non-

destructive testing method was carried out to determine the

compressive strengths of the clay brick, mortar, and plaster.

The compressive strength of clay brick, mortar and plaster

is indicated as 14 MPa, 5 MPa and 5 MPa, respectively.

Anchorage steel rods of 4 different diameters and 3

different depths were used in the anchorage shear tests

carried out in a masonry building with clay bricks. The test

results obtained at different anchorage diameters (Ø) and

anchorage depths (Lad) are given in table 2. In the pull-out

tests, Ppi showed lower performance than Pfi.

Figure 6. Pull-out test with full interaction.

Figure 7. Pull-out test with partial interaction.

Figure 8. Collapsing types in pull-out tests a) adherence collapse in the wall with Pfi and b) conical collapse in the wall with Ppi

Sådhanå (2021) 46:184 of 13 184

When the pull-out force (P) data (keeping the anchor

diameter (Ø) the same for the anchorage depth (Lad) was

compared, it was seen that the maximum decrease of per-

centage in pull-out force (Pmax) was varied between 23 and

63 in the transition from Pfi to Ppi for 5 cm depth (table 2).

Equations of Pmax and Pfi and Ppi depend on Ø obtained

from the anchorage pull-out experiments given in table 2

were drawn with the excel program and shown in figure 12.

According to the results of the Pfi test, it was observed that

as the anchorage diameter (Ø) and anchorage depth (Lad)

increased, the pull-out force (Pfi) increased. It has been

observed that Ø greatly affects the Pfi values, and negligibly

affects the Ppi values. For the same anchorage depth, the

ratio of Ppi to Pfi is about 70% for the anchor diameter (Ø)

Figure 9. Shear test set- up of rods anchored to the wall.

Figure 10. Anchor reinforcement shear test set-up.

Figure 11. The failure of anchor steel rods in the wall.

Table 2. Pull-out capacities depend on anchor diameter and

depth (Pmax).

Anchor depth (Lad) (cm)

Pmax (kN)

Group Ø 10 Ø 12 Ø 14 Ø 16

5 cm Pfi 3.35 4.56 7.00 8.52

10 cm Pfi 6.69 9.43 11.56 13.38

15 cm Pfi 8.82 11.26 13.38 16.12

5 cm Ppi 2.43 2.43 2.74 3.04

2.74 3.04 3.35 3.35

10 cm Ppi 4.87 4.87 5.48 5.17

4.26 4.56 4.87 5.48

15 cm Ppi 5. 48 5. 48 6. 69 6. 69

6. 08 6. 69 6. 39 7. 30

*2 cm plaster allowance was added to the Øs given above and holes were

made on the wall.

184 of 13 Sådhanå (2021) 46:184

10 mm, while the anchor diameter (Ø) decreases to about

40% for 16 mm. It has been observed that the use of thin

diameter anchors is more important in masonry building

reinforcements. It was observed that the anchorage diam-

eter (Ø) increased from 10 mm to 16 mm and the anchorage

depth (Lad) increased from 5 cm to 15 cm and the

anchorage pull-out capacity (Pmax) increased to 2.70 times

for Ppi and 4.82 times for Pfi.

As can be seen in figures 13 and 14, it has been observed

that with the increase of the anchorage depth (Lad), which is

5, 10 and 15 cm, the anchor pull-out maximum force

(P) continues with a decreasing slope. It has been observed

that Lad is the most effective parameter for both Pfi and Ppiin the pull-out performance of anchors. It was concluded

that the embedment depth should be close to the thickness

of the wall to be anchored. It has been observed that the

effect of Ø is higher in Pfi, but less in Ppi, depending on the

pull-out strength of the brick and masonry mortar.

In table 3, from the data obtained from partial and full

interaction experiments; Equations over R2 = 0.99 with

significant regression between P (kN) depending on dif-

ferent Lad (cm) and Ø (mm) were created by drawing the

graphs of the obtained data with the Excel program. With

these Equations, P (kN) values can be obtained depending

on Lad (cm) and Ø (mm).

Since the collapse occurred in the pull-out experiments

of the anchors occurred at the wall interface with chemical

anchorage, the diameter of the hole drilled on the wall

surface (D) which is 4 mm bigger than the anchorage

diameter (Ø) was used in the equations instead of the

anchorage diameter (Ø). Significant Equations with

regression of 97% and 98% were created between Pfi and

Ppi depending on D (mm) and Lad (cm), respectively

(table 4).

The hole diameter (D) was used when calculating the

adherence shear stress (kN/mm2) due to the weaker col-

lapse at the interface between brick and epoxy. Accord-

ingly, by using D (mm) in partially or fully interacted

anchorage pull-out experiments, significant Equations with

regressions of 98% and 84% for adherence shear stresses spiand sfi, respectively, depending on Lad (cm) and D (mm)

have been created (table 5).

In figure 15, significant equations were obtained between

Pfi and Ppi for samples with different anchorage diameters

(Ø). Here, it was observed that as the Ø gets smaller, the

difference between Pfi and Ppi decreases, and the pull-out

strength of the wall and consequently the effect of conical

failure decreases. Using these equations, instead of the

more laborious Ppi test, it will be possible to determine the

Ppi strength based on the easier Pfi test results and to be

used in the strengthening calculation analysis.

It was observed that as the effect of anchorage depth on

shear performance decreases with increasing wall strength,

effective embedment depth will be less. In Equations (1)-

(4), for anchor specimens of different diameters, between

pull-out force with full interaction (Pfi) and with partial

interaction (Ppi), the following equations are obtained:

0

2

4

6

8

10

12

14

16

18

10 12 14 16

Pull-

out f

orce

(kN

)

Anchor diameter Ø (mm)

Figure 12. Pull-out force equations with full and partial

interaction depending on the anchor diameter (Ø) for different

anchorage depth.

0

2

4

6

8

10

12

14

16

18

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

Ø 10 Anchor Ø 12 Anchor Ø 14 Anchor Ø 16 Anchor

Pull-

out f

orce

(kN

)

Anchor depth (cm)

Figure 13. Pfi for different anchor diameters depending on

anchor depth (Lad).

0

1

2

3

4

5

6

7

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

Ø 10 Anchor Ø 12 Anchor Ø 14 Anchor Ø 16 Anchor

Pull-

out f

orce

(kN

)

Anchor depth (cm)

Figure 14. Anhor diameters depending on anchor depth (Lad).

Sådhanå (2021) 46:184 of 13 184

Pfi ¼ 2:4146� Ppifor ø16 anchorage, with 98:98% regression

ð1Þ


ð2Þ


ð3Þ


ð4Þ

As seen in figure 16, it has been observed that a = Pfi /Ppiratio changes depending on the diameter of the reinforce-

ment (mm) and depending on the diameter, there is a

meaningful Equation with 98.88% regression between Pfiand Ppi (Equations (5) and (6)).

Pfi ¼ a� Ppi ð5Þ

a ¼ 0:152� ø ð6ÞShear test results for Ø10, Ø12 and Ø16 anchor steel rods

at different anchorage depths are given in table 6 and fig-

ures 17-19.

As can be seen in table 6 and figures 17-19 in these

experiments, it was observed that the maximum force,

displacement amount and potential energy absorption

capacity increased significantly as the anchorage depth

increased. However, it has been observed that these

increases are very small compared to the increase in

Table 3. Pull-out equations for full and partial interaction forces depending on anchor depth.

Anchor diameter (Ø) (mm)

Full interaction Partial interaction

Pfi (kN) R2 (%) Ppi (kN) R2 (%)

Ø10 Pfi =-0.01159Lad2?0.76539Lad 99.83 Ppi=-0.01369Lad

2?0.599Lad 99.99

Ø12 Pfi =-0.02569Lad2?1.14649Lad 99.24 Ppi =-0.01389Lad

2?0.61169Lad 99.99


2?0.68779Lad 100.00


2?0.69739Lad 99.93

Table 4. Pull-out equations for full and partial interaction

depend on anchor depth (cm) and anchor hole diameter (mm).

P (kN) equations R2 (%)

Pfi Pfi=0.6549Lad?1.079D-15.220 97

Ppi Ppi=0.3469Lad?0.159D-1.275 98

Table 5. Adherence shear stress (s) equations depending on

different anchor hole diameter (D) and depth (Lad).

s (kN/mm2) equations R2 (%)

Pfi sfi=0.348-0.069Lad?0.1249D 84

Ppi spi=1.663-0.0299Lad-0.0259D 98

Figure 15. Pfi - Ppi graph for different anchor diameters (Ø).

184 of 13 Sådhanå (2021) 46:184

diameter. It has been observed that the shear values of 3

different anchor diameters are close to each other for the

same embedment depth.

It is seen that the shear performance increases by about

10% despite the 50% increase in the anchor diameter.

Therefore, it has been concluded that it would be healthier

to prefer Ø10 anchors compared to others (figure 20).

In figure 20 total shear forces applied on shear plate with

four anchors are given. Equations for shear capacity of an

anchor depending on the mean of all anchorage depths for

the anchors of Ø10, Ø12 and Ø16 with regression up to

100% are respectively given below:

Vmax ¼ �0:0387L2ad þ 1:6047Lad R2 ¼ 0:9997 for ø10

ð7Þ


ð8Þ


ð9ÞThe optimum length of anchorage depth depends on the

resistance of the plaster, mortar, and bricks. It was observed

that the optimum anchorage depth decreased in parabolic

with increasing the anchorage diameter. For this building,

by taking the derivation of the second-order equations

given above, optimum anchorage depth depending on the

anchor diameter; Lad = 20.73 cm for Ø10, Lad = 19.17 cm

for Ø12 and Lad = 18.26 cm for Ø16 mm. Therefore,

making the anchorage depth greater than the optimum Lad

does not have any contribution, but it has shown that the

ductile behavior increases with the increase of the

anchorage depth, thus the ideal embedment depth is the

optimum anchorage depth (Equations (7)-(9)).

0.0

0.5

1.0

1.5

2.0

2.5

3.0

8 9 10 11 12 13 14 15 16 17

a=P f

i/Ppi

Anchor diameter (mm)

Figure 16. Pfi and Ppi relation based on anchor diameter.

Table 6. Maximum shear force and displacement at maximum

load.

Anchor diameter and

depth

Max shear force,

Vmax (kN)

Displacement

(mm)

Ø10- 5 cm 27.65 18

Ø10 - 10 cm 49.27 42

Ø10 - 15 cm 61.23 100

Ø12 - 5 cm 31.16 19

Ø12 - 10 cm 51.28 56

Ø12 - 15 cm 64.32 86

Ø16 - 5 cm 34.64 11

Ø16 - 10 cm 54.81 48

Ø16 - 15 cm 68.71 95

0

10

20

30

40

50

60

70

0 20 40 60 80 100 120 140

5 cm Depth 10 cm Depth 15 cm Depth

Shea

r fo

rce

(kN

)

Displacement (mm)

Figure 17. Shear and displacements for Ø10 anchor

reinforcement.

0

10

20

30

40

50

60

70

0 20 40 60 80 100 120 140


Shea

r fo

rce

(kN

)

Displacement (mm)


reinforcement.

0

10

20

30

40

50

60

70

0 20 40 60 80 100 120 140


Shea

r fo

rce

(kN

)

Displacement (mm)


reinforcement.

Sådhanå (2021) 46:184 of 13 184

While the increase in the shear capacity decreases with

increasing the anchorage depth (figure 20), it has been

observed that the parabolic increase in the displacement is

increasingly inclined (figure 21), therefore, the connection

between the existing wall and reinforcement element will

behave more inelastic and ductile with the increase in the

anchorage depth.

As it can be understood from figures 22-24, the anchor-

age behaved more ductile with the anchorage embedment

depth increasing from 5 cm to 10 cm. It was observed that

the energy absorption capacity increased approximately 4

times in parallel with the deformation, and the energy

absorption capacity increased approximately 8 times with

the increase in the embedment depth from 5 cm to 15 cm.

Considering that this increased amount does not increase

linearly with the embedment depth and decreases parabol-

ically, it is seen that if the anchorage depth is more than 15

cm, it will decrease very much, and after 20 cm it will be

negligible.

As can be seen in figure 24, the effect of the change of

anchorage diameters of Ø10, Ø12 and Ø16 on the shear

force applied to the anchor reinforcement at 15 cm

embedment depth and the energy absorption capacity it

means is negligible. It has been observed that masonry

brick and masonry mortar strength is the first-order effec-

tive parameter and the effect of reinforcement diameter on

shear performance is negligible.

In addition, in Equations (10)-(12), the ratios of pull-out

with full interaction to shear force are given in anchor

specimens of different diameters and between shear force

(Vmax) and pull-out with full interaction (Pfi) in the fol-

lowing equations:

0

10

20

30

40

50

60

70

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

Ø10 Ø12 Ø16Shea

r fo

rce

(kN

)

Anchor depth (cm)

Figure 20. Vmax-Lad relation for anchors of Ø10, Ø12 and Ø16.

0

10

20

30

40

50

60

70

80

90

100

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

Ø10 Ø12 Ø16

Dip

lace

men

t (m

m)

Anchor depth (cm)

Figure 21. Displacement-anchor depth for Ø10, Ø12 and Ø16

anchors.

0

10

20

30

40

0 10 20 30 40

Shea

r fo

rce

(kN

)

Diplacement (mm)

Figure 22. Shear load-displacement of different anchor diame-

ters for 5 cm anchors.

0

10

20

30

40

50

60

70

80

0 10 20 30 40 50 60 70 80 90 100 110 120

Shea

r fo

rce

(kN

)

Diplacement (mm)



0

10

20

30

40

50

60

0 10 20 30 40 50 60 70 80 90 100

Shea

r fo

rce

(kN

)

Diplacement (mm)



184 of 13 Sådhanå (2021) 46:184

Vmax ¼ 7:21� Pfiwith 99:18% regression for ø10 anchor;

ð10Þ

Vmax ¼ 5:73� Pfiwith 98:70% regression for ø12 anchor;

ð11Þ

Vmax ¼ 4:18� Pfiwith 99:95% regression for ø16 anchor

ð12Þ

From the equations obtained in figure 25, there are the

following equations between Pfi and shear force (Vmax)

depending on diameter with 98.32% regression:

b ¼ 0:0146� ø ð13ÞVmax ¼ Pfi=b ð14Þ

Here, the pull-out strength is the first-order parameter

depending on the anchor depth, while the maximum

effective depth in shear strength is determined as approxi-

mately 20 cm, and since the most effective force will be the

shear force between the existing wall and the reinforcement

element, the most important criterion in the dimensioning

of the anchors will be the shear performance. In this case,

as the most practical method in determining the shear

performance depending on the anchor diameter, starting

from the result of the easy test, the pull-out test with full

interaction, the Ø value can be found in Equation (13) and

the coefficient b can be found and the shear strength can be

calculated by placing it in Equation (14).

In this study, to determine the number of the connectors

to be anchored to the masonry wall surface, an existing

building constructed using commonly used clay bricks and

techniques in the preparation of mortar and plaster in

Turkey is chosen as a sample for testing. The mechanical

properties of the wall in this building appear to be quite

different from previous studies in Ceroni’s study [22] in

terms of the compressive strength of the mortar and wall,

the confinement pressure, and the maximum experimental

tensile strength. Although there was a good correlation

between the pull-out test results regarding the increase in

the performance of the connectors due to the increase in the

anchor embedding and hole diameter, it was not possible to

compare the test results with the current test results pre-

sented by Ceroni [22].

4. Conclusions and Suggestions

This study, it is aimed to determine the anchor shear per-

formance by a simpler pull-out with full interaction, since

the shear test and the pull-out with partial interaction tests

are quite difficult and time-consuming. For this purpose,

two different types of practical and useful steel plate test

apparatus were specially designed for experimental set-ups.

These two apparatuses were used to determine the shear

performance and pull-out performance with partial inter-

action of reinforcement steel rods with different diameters

and embedment depths anchored to the walls of an existing

5-storey masonry building with clay bricks in Ankara.

Here, 12 pull-outs with full interaction tests, 24 pull-outs

with partial interaction tests, and 9 shear tests were con-

ducted. Following results were obtained as a result of this

study:

• It has been observed that the pull-out force of the fully

interacted anchors (Pfi) is higher than the pull-out force

of the partially interacted anchors (Ppi), so to be closer

to the scientific facts in the design of the anchors under

the pull-out effect, the results of the Ppi pull-out test

should be taken as reference.

• It has been observed that the anchor diameter has little

effect on the realistic Ppi pull-out capacity compared to

the anchor depth. Therefore, when the ease of appli-

cation is also taken into consideration, it has been

observed that the pull-out capacity of the smallest

diameter (Ø10) anchor is close to the larger ones, and

thin diameter anchors are recommended for pull

anchor applications.

• For this building, by taking the derivation of the

second-order equations, optimum anchorage depth was

varied depending on the anchor diameter. The opti-

mum anchorage depth depending on the anchor

diameter; Lad = 20.73 cm for Ø10, Lad = 19.17 cm

for Ø12 and Lad = 18.26 cm for Ø16 mm. Therefore,

making the anchorage depth greater than the optimum

Lad does not have any contribution, but it has shown

that the ductile behavior increases with the increase of

the anchorage depth up to the optimum. Thus the ideal

embedment depth is the optimum anchorage depth.

This varies from building to building so it should be

determined for other buildings with different material

properties before strengthening analysis.

• The adherence between the reinforcement and the

epoxy is stronger than the adherence at the epoxy-wall

interface, and the collapse occurs at the epoxy-wall

interface, so when calculating the adherence surface

area in the adherence pull-out capacity calculations,

0.00

0.05

0.10

0.15

0.20

0.25

0.30

8 10 12 14 16

b=P f

i/Vm

ax

Anchor diameter (mm)

Figure 25. The ratio of pull-out force with full interaction to

shear force depend on anchor diameter.

Sådhanå (2021) 46:184 of 13 184

the hole diameter (D) is essential instead of the anchor

reinforcement diameter (Ø). It is more important that

the anchorage holes are not left dusty and cleaned well

with a compressor. However, if ribbed reinforcement is

used in anchors to reduce the use of epoxy, it has been

observed that Ø10 anchors have D=Ø?4 mm hole

diameter for ease of application and keep D larger will

not be meaningful.

• In addition, for any anchorage depth, depending on the

reinforcement diameter, it is determined that the ratio

of Pfi/Ppi is variable and the equation Pfi = 0. 152Ø9Ppisignificant with 98.94% regression between them.

• While the increase in the diameter of the anchor

reinforcement has a great effect on the anchorage Pficapacity, it has been observed that its effect on the Ppicapacity, shear capacity and energy absorption capac-

ity is negligible, so it would be more meaningful to

prefer thin reinforcement in anchor in terms of ease of

application and economy.

• It was observed that the shear performance increased

parabolically with a decreasing trend in line with the

increase in the anchor embedment depth. It has been

observed that if this increase in anchor depth is made

more than 20 cm, its contribution to the shear capacity

will be minimized and it will increase the cost.

• With the increase in anchor embedment depth from 5

cm to 15 cm, it has been observed that there is an

increase of approximately 8 times in the ductility level

and proportionally in the energy absorption capacity.

• It has been observed that the thinnest Ø10 anchor rods

showed a ductile behavior with a bigger collapse

deformation in comparison to the other thick diameter

anchors. In terms of allowing the redistribution of the

load among the anchors and preventing the early brittle

failure of connections, ductile connection showed a

great advantage in terms of nonlinear analysis of a

strengthened system.

• The use of reinforcement anchor rods, which are more

ductile and readily available as the anchor, makes

reinforcement connections more ductile. The shear

strength is approximately seven times bigger than the

pull-out strength of Ø10 anchor rods. Thin anchors

under the effect of shear load are more easily bent in

the wall than thick anchors. It was found important in

terms of decreasing the shear stress and increasing the

tensile stress in its cross-section because the tensile

strength of the steel rod is bigger than the shear

strength of the steel rod.

• In the case of strengthening of relatively higher

strength, concrete walls instead of brick walls, the

bending in the anchor rods will decrease because the

crushing will be less. Because of the non-ductile

behavior of the connection, the anchor steel rods

cannot redistribute their overloads to the less loaded

anchor steel rods and earlier shear failure will occur.

Thus, the effect of the increase in the anchorage depth

on the shear performance will decrease, and the

effective embedment depth will also be less.

• This study was carried out on an existing masonry

building that is going to be destroyed because of the

earthquake. These testing results were only found out

for this building with specific material properties. All

these results (especially adherence shear strength) will

vary on a different building and a masonry different in

terms of units and mortar. So, these tests should be

carried out on different masonry buildings to obtain

more reliable equations.

References

[1] Ceran H B and Erberik M A 2013 Effect of out-of-plane

behavior on seismic fragility of masonry buildings in

Turkey. Bull. Earthquake Eng. 11: 1775–1795.[2] Shabdin M, Zargaran M and Attari N K 2018 Experimental

diagonal tension (shear) test of Un-Reinforced Masonry

(URM) walls strengthened with textile reinforced mortar

(TRM). Constr. Build. Mater. 164: 704–715.[3] ElGawady M, Lestuzzi P and Badoux M 2004 A review of

conventional seismic retrofitting techniques for URM. In:

Proceedings of the 13th International Brick and BlockMasonry Conference, Amsterdam, pp. 1–10

[4] Yon B, Onat O, Oncu M E and Karasin A, 2020 Failures of

masonry dwelling triggered by East Anatolian Fault earth-

quakes in Turkey. Soil Dyn. Earthquake Eng. 133: 106–126.[5] Lin T J and LaFave J M 2012 Experimental structural

behavior of wall-diaphragm connections for older masonry

buildings. Constr. Build. Mater. 26: 180–189.[6] AlShawa O, Liberatore D and Sorrentino L 2019 Dynamic

one-sided out-of-plane behavior of unreinforced-masonry

wall restrained by elasto-plastic tie-rods. Int. J. Archit.Heritage 13: 340–357.

[7] Paganoni S and D’Ayala D 2010 Experimental and compu-

tational validation of dissipative prototype for the seismic

protection of heritage buildings. Adv. Mater. Res. 133:

831–836.

[8] Riccadonna D, Giongo I, Schiro G, Rizzi E and Parisi M A

2019 Experimental shear testing of timber-masonry dry

connections for the seismic retrofit of unreinforced masonry

shear walls. Constr. Build. Mater. 211: 52–72.[9] Taghdi M, Bruneau M and Saatcioglu M 2000 Seismic

retrofitting of low-rise masonry and concrete walls using

steel strips. J. Struct. Eng. 126: 1017–1025.[10] Ghiassi B and Mohammadi M S 2012 A performance-based

method for seismic evaluation of masonry walls strengthened

with RC layers. In: Proceedings of 15th World Conferenceon Earthquake Engineering, Lisbon, Portugal

[11] Paganoni S and D’Ayala D 2014 Testing and design

procedure for corner connections of masonry heritage

buildings strengthened by metallic grouted anchors. Eng.Struct. 70: 278–293.

[12] Arifovic F and Nielsen M P 2004 Strength of anchors inmasonry. Department of Civil Engineering, Technical

184 of 13 Sådhanå (2021) 46:184

University of Denmark, Rapport BYG DTU, ISBN 87-7877-

205-2

[13] Ceroni F, Cuzzilla R and Pecce M 2016 Assessment

of performance of steel and GFRP bars as injected

anchors in masonry walls. Constr. Build. Mater. 123: 78–98.[14] Burton C, Visintin P, Griffith M and Vaculik J 2020 Field

testing of vintage masonry: Mechanical properties and

anchorage strengths. Structures. 28: 1900–1914.[15] Giresini L, Puppio M L and Taddei F 2020 Experimental

pull-out tests and design indications for strength anchors

installed in masonry walls. Mater. Struct. 53: 1–16.[16] Munoz R, Lourenco P B and Moreira S 2018 Experimen-

tal results on mechanical behaviour of metal anchors in

historic stone masonry. Constr. Build. Mater. 163: 643–655.[17] Panizza M, Girardello P, Garbin E, Valluzzi M R, Cardani G,

Dalla Benetta M and Casadei P 2015 On-site pull-out tests of

steel anchor spikes applied to brickwork masonry. Key Eng.Mater. 624: 266–274.

[18] Giuriani E, Gattesco N and Del Piccolo M 1993 Experimental

tests on the shear behaviour of dowels connecting concrete

slabs to stone masonry walls. Mater. Struct. 26: 293–301.[19] Choi Y H and LaFave J M 2004 Performance of corrugated

metal ties for brick veneer wall systems. J. Mater. Civ. Eng.16: 202–211.

[20] Kucharczyk A and Urbanska K 2019 Impact of Anchoring

Steel Mast Structure on the State of Stress and Strain in

Existing Masonry Buildings. IOP Conf. Ser.: Mater. Sci.Eng. 471: 052037

[21] Binda L, Modena C, Valluzzi M R and Zago R 1999

Mechanical effects of bed joint steel reinforcement in historic

brick masonry structures. In: Proceedings of the 8th Int. Conf.and Exhibition, Structural Faults? Repair, London, pp. 3–13

[22] Ceroni F and Di Ludovico M 2020 Traditional and

innovative systems for injected anchors in masonry ele-

ments: Experimental behavior and theoretical formulations.

Constr. Build. Mater. 254: 119178.

Sådhanå (2021) 46:184 of 13 184

in situ determination of the mechanical performance of the

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