structural behaviour of beam column …technicaljournalsonline.com/ijeat/vol vii/ijaet vol vii...key...

B. Venkatesan et al., International Journal of Advanced Engineering Technology E-ISSN 0976-3945

Int J Adv Engg Tech/Vol. VII/Issue II/April-June,2016/1272-1280

Research Paper

STRUCTURAL BEHAVIOUR OF BEAM COLUMN JOINT RETROFITTED WITH FERROCEMENT LAMINATES

B. Venkatesana, R. Ilangovan

b Address for Correspondence

a Dept. of Civil Engineering, University VOC College of Engineering.- Thoothukudi-628008. b Dept. of Civil Engineering, University College of Engineering- Dindigul-624622.

ABSTRACT An Experimental study is executed to evaluate a retrofit technique for strengthening shear deficient beam column joint. One of the techniques of strengthening the RC structural members is through confinement with a composite enclosure. . In column was restrained as axial load. In this study totally four specimen were tested under cyclic loading in cantilever portion using hydraulic push and pull jack in which two as reference specimen and remaining two used for strengthen specimen with the Ferrocement laminate is a composite material collective with weld mesh and woven mesh embedded of 3.44 volume fraction. The hysteretic load displacement curve has been plotted and the energy dissipation capacity of the reference specimen compared with the cementitious laminate retrofitted beam-column joint from the experimental result, the laminate strengthened specimen showed more effective increasing the ultimate load carrying capacity, stiffness and energy dissipation. The analytical results showed comparable with the experimental result. KEY WORDS: Seismic, Beam-column joints; Ferrocement, cyclic, Energy dissipation, stiffness

1. INTRODUCTION Earthquake can cause reinforced concrete buildings to collapse, loss of lives and also staggering economic losses. Most of the structures are notable to resist moderate or major earthquake loading. Under seismic loading, it is important for RC building to have lateral resistance capacity against brittle failure. Non-seismic design buildings which are designed using non-seismic code of practice are vulnerable to earthquake excitations. Since demolishing and reconstructing RC buildings are expensive, retrofitting the small fraction of structural components and building may offer a workable solution for ensuring the safety of the building and people. Ferrocement is a popular material which is normally used in strengthening RC structural element since recent years. Recent earthquakes have shown that older RC buildings and bridges are susceptible to beam-column joint failure. The beam-column joint dimensions and reinforcement details of older RC structures were determined from the sizes of adjacent framing members and the compression development length requirements for longitudinal reinforcement. Moreover, transverse reinforcement in beams and columns was discontinued typically at the face of the joint, leaving the joint without any transverse reinforcement. It is often impractical to retrofit older, lightly reinforced building and bridge beam-column joints with the volume and details of transverse steel reinforcement recommended for new structures. The finite element analysis of beam column joints retrofitted with glass fiber reinforced polymer sheets (GFRP) carried out using ANSYS software. The first specimen is the control specimen. This had reinforcement as per code IS 456:2000. This had reinforcement as per code IS 13920:1993.The third specimen had reinforcement as per code IS 456:2000 and was retrofitted with glass fiber reinforced polymer (GFRP) sheets. The performance of the retrofitted beam-column joint was compared with the control specimens. Abhijit (2004) concluded that the load carrying capacity of the reinforced concrete beam-column joint specimens designed and detailed as per code IS 13920:1993 was found to be 15 % - 16 % more than the specimens detailed as per code IS 456:2000. Joints have been cast with adequate and deficient bond of reinforcements at the beam-column joint. FRP sheets and strips have been applied on the joints in different configurations. The columns are subjected to an axial force while the beams are

subjected to a cyclic load with controlled displacement. The amplitude of displacement is increased monotonically using a dynamic actuator. The hysteretic curves of the specimens have been plotted. The energy dissipation capacity of various FRP configurations has been compared. In addition, the control specimens have been reused after testing as damaged specimens that are candidates for rehabilitation. The rehabilitation has been carried out using FRP and their performance has been compared with that of the undamaged specimens. Four exterior beam column joint were casted and tested under cyclic load. The specimens which had joint reinforcement as per code IS 13920:1993 with inclined bars and the specimens without inclined bars were tested. Bindu (2008) concluded that the specimen with inclined bars shows more ductility and energy absorption capacity than specimen without inclined bars. Five full scale interior beam column joint sub assemblages were casted and tested under cyclic loading. Out of which two specimens were designed and detailed as per Canadian code and other three had different retrofitting scheme with different confinement. Said et al. (2004) concluded that FRP rehabilitation schemes exhibits remarkable enhancement in terms of load carrying capacity of the specimen. Beam column joints were constructed according to the existing practice and tested under cyclic lateral loading to determine the effect of using high performance steel fiber reinforced concrete in place of conventional concrete in the joint region. The properties of ultimate strength, ductility, energy dissipation capacity and joint stiffness of the reference concrete specimens were compared with those containing different amounts of brass – coated or hook steel fibers. Nabeela (2005) determined that the steel fiber concrete specimens exhibited three times higher load levels, 20 times larger energy dissipation, and two times slower stiffness degradation compared to the reference concrete specimens. Using hooked steel fibers showed a significant increase in maximum load carrying capacity and in the initial secant stiffness compared to the reference specimens. Eight interior beam - column joints were casted and designated as virgin specimens and tested up to failure .Out of eight specimens, four of the specimens were externally wrapped with glass fibre reinforced polymer sheets and other four specimens with carbon fibre reinforced polymer sheets. These rehabilitated specimens were



tested up to failure. The performances of the rehabilitated beam-column joint specimens were compared with the virgin beam-column joint specimens. Ravindra V (2009) concluded that the rehabilitated specimens of glass fibre reinforced polymer and carbon fibre reinforced polymer beam-column joint specimens exhibited an improved load carrying capacity and a higher rate of stiffness than the virgin specimens. Three exterior reinforced concrete beam-column joint specimens (control) were cast and tested to failure. Two specimens had reinforcement details as per code IS 456:2000. The other specimen had reinforcement details as per code IS 13920:1993. An axial load was applied on the column. Push and pull load was applied at the free end of the cantilever beam till failure. The failed two beam-column joint specimens designed as per code IS 456:2000 were retrofitted with GFRP-AFRP/AFRP-GFRP hybrid fiber sheets wrapping to strengthen the specimens. The performance of the retrofitted beam-column joints was compared with the control beam-column joint specimens. Robert (2010) concluded that the load carrying capacity of the reinforced concrete beam-column joint specimens designed and detailed as per code IS 13920:1993 was found to be 10 % - 11 % more than the specimens detailed as per code IS 456:2000.Existing reinforced concrete (RC) columns may be structurally deficient due to variety of reasons such as improper transverse reinforcement, flaws in structural design, insufficient load carrying capacity, etc. Carbon/Glass fibre reinforced polymer (FRP) confinement can be effectively used for strengthening the deficient RC columns. An attempt has been made hereby to investigate the experimental behavior of GFRP wrapped small scale square RC columns with varying corner radii. Three columns are unwrapped and have been designated as control specimens. Three columns each with corner radius equivalent to cover of 25 mm are wrapped with one and two layers of GFRP, respectively. GFRP wrapped columns go under higher axial displacement in order to gain higher compressive strength over the control column. Sushil S S et al. (2013) concluded that GFRP wrapping can enhance the structural performance of RC columns under axial loading, in terms of both maximum strength and strain. Increasing the number of GFRP layers increases the axial compressive strengths of the columns. However, the strength increase is not in linear proportion with the number of GFRP layers. While several studies, have reported about use of FRP for strengthening the structural elements. The literature is very scarce reporting the strengthening using ferrocement laminates for beam column joint. Favvata et al. (2004) tested on Non linear dynamic analysis by hysteretic response of the exterior beam column joint with stiffness degradation and low pinching effect, without pinching effect and high pinching effect. Bindhu et al (2009) used reinforced pattern exterior joint which avoids congestion of steel to retrofit shear deficient concrete columns. Fisher et al.(2011) tested under two groups of different joint

design of reinforcement detailing, joints reinforced with traditional steel rebar and another group of prefabricated cage system (PCS), the result of this research show that the PCS reinforced joints had slightly higher strength. Pradip et al (2007) investigated the very critical element in RC framed structure intersect in all directions. Costas et al. (2002) presented the analysis of reinforced concrete joints and strengthened with composite material in the form of externally bonded reinforcement analytical shear strength predictions which were in good agreement with test results. Kakaletsis D et al.(2011) provided the seismic retrofit of existing RC structure on experimental study of CFRP. Umut et al. (2002) used as a basis for a parametric study to investigate the effect of different strengthening of exterior joint ends under various axial loads. The performance of exterior joint assemblages detailed for earthquake loads as per IS13920:1993 and detailed as per current Indian code of practice for concrete design IS456:2000 are compared with the retrofitted specimens. The experimental results are validated with the analytical model developed using finite element software package ANSYS. 2. EXPERIMENTAL STUDY 2.1 Ferrocement According to ACI549, ferrocement is a thin walled section less than 25 mm thick containing closely spaced small diameter wire mesh and cement mortar. In this study, ferrocement laminates of volumetric fraction 3.44 with welded and woven mesh mixed the ratio of 2:1 CM for the cross section of 500 mm x 125 mm x 25 mm thick laminate were casted. The properties of the welded and woven meshes used in the ferrocement laminate were diameters of 1.42 mm and 0.82 mm and openings of 16 mm and 4.5 mm, with cross-sectional areas of 1.58 mm2 and 0.52 mm2, ultimate strengths of 692.36 N/mm2 and modulus of elasticity 1.36 x 105 N/mm2. The laminate system has been cast in two parts as shown in fig.1.Epoxy bonding system were adopted after surface preparation on the specimen. The laminate and bond line thickness of 2mm was followed in all the test specimens, specimen details are shown in Table 1.

Fig. 1: Wrapping details of Ferrocement laminate

TABLE 1: REFERENCE AND RETROFITTING DETAILS OF BEAM COLUMN JOINT SPECIMEN S. No. Specimen Reinforcement Detail Retrofitting Detail 1 ND-1 Non Ductile

Reference specimen 2 DD-1 Ductile 3 ND-L2T2 Non Ductile Retrofitting specimen, Vf = 3.44 4 DD-L2T2 Ductile



2.2 Beam column joint The beam column joint specimen are designed as per IS 456-2000 and IS 13920-1993, whereas the size of the specimen are of 230 mm x 230 mm cross section

for both beam and column and the length of 1250 mm for the cantilever beam, for column the height is 2000 mm. The details of reinforcement for ductile and non-ductile specimen are shown in fig. 2 and 3.

Fig 2: Reinforced details for Ductile joint (Type DD)

Fig 3: Reinforced details for Non-Ductile joint (Type ND)

2.3 Testing Arrangement The experimental setup for a beam column joint is shown in fig.4. Deflections on beam are measured using dial gauges at the mid span of the beam and at the free end. A hydraulic jack of 500 kN capacity was used vertically to the loading frame for simulating the axial capacity of the column held in position but not restrained in direction (partially fixed end conditions) was obtained through the application of load in the axial direction on the column. A constant axial load of 100 kN, which is about 20 percent of the axial load

of the column was applied to the column for holding the specimen in position. Another 500 kN capacity hydraulic push and pull jack was used to apply reverse cyclic load to the beam portion of the joint. The point of application of the cyclic load was at 50mm from the free end of beam. The displacement increment was fixed as 5mm, for push and pull of all specimens. The specimen was instrumented with linear variable different transducer having range ±75mm to measure the displacement at loading point.



Fig 4: Test set up of beam column joint specimen in the loading frame

3. RESULTS AND DISCUSSION 3.1 Reference Specimen The hysteresis behavior of the control specimen ND-1 and DD-1 are shown in fig.5. The ND-1 specimen observed maximum load of 20.2 kN in push and 19.4kN in pull respectively and the specimen failed when the displacement in 30 mm. The total collective load observed is 1031.67kN (Table 2).For DD-1 the maximum load observed is 24.5kN in push and 23.6kN respectively the specimen failed when the

displacement in 35 mm. The total collective load is 1752.57 kN (Table 2).The increase in energy dissipation for ductile detailed specimen DD-1 when compared to non-ductile detailed specimen is 41.1 percent. The collective energy dissipation and stiffness for ND-1 and DD-1 specimen are given in fig.6.The increase in energy dissipation of ductile detailed beam is 41.1 percent when compared with the non-ductile detailed beam column joint specimen.

Fig: 5.Hysteresis behavior of beam column joint specimen ND-1 and DD-1

Fig: 6.Collective energy dissipation and stiffness Vs. Displacement



TABLE 2: COMPARISON OF LOAD, ENERGY DISSIPATION AND STIFFNESS

Sp

ecim

en

Ma

xim

um

Loa

d, k

N

Energy Dissipation at Various

Displacement and Stiffness for the beam

column joint specimen

Sp

ecim

en

Ma

xim

um

Loa

d, k

N

Energy Dissipation at Various

Displacement and Stiffness for the beam

column joint specimen p

ush

Pu

ll

Def

lect

ion

mm

5.0

0

10.

00

15.

00

20.

00

25.

00

30.

00

35.

00

40.

00

45.

00

pu

sh

Pu

ll

Def

lect

ion

mm

5.0

0

10.

00

15.

00

20.

00

25.

00

30.

00

35.

00

40.

00

45.

00

ND

-T2L

2

30.2

29.5

En

ergy

Dis

c. An

al.

83.0

3

288.

03

650.

24

1103

.13

1633

.73

2256

.26

2889

.04

3451

.04

4173

.69

DD

-T2L

2

35.8

34.6

En

ergy

Dis

c. An

al.

95.2

2

367.

37

824.

62

1371

.22

2037

.52

2768

.3

3540

.44

4294

.7

5147

.63

Exp

.

91.9

2

314.

98

675.

9

1132

.14

1655

.92

2211

.29

2808

.73

3438

.84

4118

.27

Exp

.

103.

37

388.

62

848.

6

1421

.75

2074

.52

2815

.62

3605

.72

4375

.32

5250

.91

Sti

ffn

ess A

na

l.

3.65

2.55

1.9

1.5

1.2

0.98

0.78

0.6

0.45

Sti

ffn

ess A

na

l.

5.2

3.5

2.53

1.9

1.44

1.1

0.8

0.52

0.33

Exp

.

4.4

2.8

2.1

3

1.6

5

1.2

7

1.0

3

0.8

1

0.6

3

0.4

6

Exp

.

5.4

3.6

2.6

1.9

5

1.5

2

1.1

8

0.9

1

0.6

7

0.4

2

ND

1

20

.2

19

.4

En

ergy

Dis

c. An

al.

42.

80

132

.18

289

.15

480

.13

731

.74

989

.34

DD

1

24

.5

23

.6

En

ergy

Dis

c. An

al.

48.

24

157

.91

335

.61

593

.01

939

.76

131

4.73

173

4.12

Exp

.

46

.90

14

7.20

30

7.88

50

2.98

76

0.44

10

31.6

7

Exp

.

51

.15

17

4.10

36

8.20

63

7.34

98

0.14

13

59.7

6

17

52.5

7

Sti

ffn

ess A

na

l.

2.60

1.75

1.23

0.90

0.68

0.48

Sti

ffn

ess A

na

l.

3.00

2.00

1.45

1.03

0.75

0.47

0.26

Exp

.

3.0

0

1.9

0

1.3

0

0.9

0

0.7

0

0.5

0

Exp

.

3.6

0

2.3

5

1.6

0

1.1

7

0.8

4

0.5

6

0.3

2

Where: Energy Disc. - Energy Dissipation

Exp. - Experimental Value Anal. - Analytical Value 3.2 Retrofitted Specimen Hysteresis behaviors of ferrocement retrofitted specimen are shown in fig.7.for ND-T2L2. The maximum load observed is 33.8kN in push and 32.2 in pull respectively and the specimen failed when the displacement is 45mm. Based on the hysteresis loops behavior energy dissipation and stiffness of cyclic load are calculated and it is given in table 2. The total collective energy dissipation observed is 4118.27 kN.mm. The stiffness degraded from 4.4kN/mm to 0.46kN/mm or DD-T2L2, the maximum load observed is 39.6kN in push and38.2kN in pull respectively and the specimen failed in 45mm displacement. The total collective energy dissipation observed is 5250 kN mm. The stiffness is degraded from 5.4kN/mm to 0.42kN/mm. This shows ferrocement with volume fraction 2.78 that performs better than ferrocement with other volume fractions. Further, the percentage increase in total collective energy dissipation for ferrocement retrofitted specimen is more than the percentage increase of energy dissipation in the case of ductile detailed specimen DD-1 compared to non-ductile detailed specimen ND-1. This clearly indicates that ferrocement retrofitting can be used as a substitute for ductile detailing if it is absent in the existing structures. The increase in total collective energy

dissipation for DD-T2L2 when that compared to DD-1 is 66percent. This shows ferrocement with volume fraction 3.44 performs better than ferrocement with other volume fractions. Further, the increase in total collective energy dissipation clearly indicates that the ferrocement retrofitting is an effective methodology for retrofitting of existing ductile detailed structures if the seismic zone is upgraded. 3.3 Crack pattern The crack pattern of the tested specimen is shown in fig.9. All specimens failed in the beam portion, yielding of steel has been observed at the point of failure. Strain gauges are bonded in the beam portion, but the strain gauges are deboned when the ultimate load and the allowable deflection occurred. 3.4 Numerical Analysis (ANSYS) The FEA (ANSYS) for analytical study of the beam column joint is subjected to Cyclic loading has been carried out. The concrete has been modeled using eight node solid element (SOLID 65) specially designed for concrete, capable of handling plasticity, creep, cracking in tension and crushing in compression The characteristics of the adopted element being non linear, requires an iterative solution. In this analysis, the compressive strength of concrete (fck) is taken as 34.23MPa and tensile strength of concrete (ft) is considered as 3.5 MPa.



The elastic modulus (Es) is 25850MPa. The reinforcing steel has been modeled using a series of two node link element (LINK 8). The material properties associated with link elements include an initial yield stress of 448 MPa. The adhesive layer has been modeled using 3Disotropic elements (SOLID45). 3.5 Beam-Column Joint Horizontal and vertical restraints, representing a pin connection were applied at the top and bottom of the column. At the end of beams, only vertical displacements were provided to simulate the cyclic

load conditions used in the test. A constant axial load of 100 kN was applied at the top end of the column. The vertical displacement at the beam end was applied slowly by increasing in monotonic manner and the results are recorded for every 5 mm vertical displacement up to failure. The ANSYS model and deflected shape of the model as shown in fig.10. Hysteresis behavior of specimen ND-1 and DD-1 as shown in fig.11. The variation of collective energy dissipation and stiffness with displacement of non-ductile specimen as shown in fig.12.

Fig: 7.Hysteresis behavior of beam column joint specimen ND-1 and DD-T2L2

Fig.9.Crack pattern of tested beam column joint

a) ANSYS model b) Deflected shape

Fig.10 ANSYS model and deflected shape of Beam column joint



a) ND-1 b) DD-1 Fig.11.Hysteresis behavior of specimen ND-1 and DD-1

(Experiment vs. Analytical Comparison)

Fig.12.Collective Energy dissipation and stiffness vs Displacement for ductile and non-ductile

3.6 Non ductile Beam Column Joint Retrofitted Specimen Hysteresis behavior of ND-T2L2 obtained using ANSYS is shown in fig.13 along with the one obtained from experiment. The maximum load observed is 33.8kN in push and 32.2 kN in pull respectively using ANSYS and 32.2kN in push and 30.8kN in pull respectively in the case of experiment and in both cases the specimen failed at 45mm

displacement. The variation of collective energy dissipation and stiffness with displacement of ANSYS and experiment as shown in fig.14. The analytical value of total collective energy dissipation is 4173.69kNmm. The stiffness degraded from 3.65kN/mm to 0.45kN/mm. The experimental value of total collective energy dissipation for ND-T2L2 is 4118.27kNmm. The stiffness of ND-T2L2 degraded from 4.4kN/mm to 0.46kN/mm.

Fig.13.Hysteresis behavior of Experiment and ANSYS specimen ND-T2L2

3.7 Ductile Beam Column Joint Retrofitted Specimen Hysteresis behavior of DD-T2L2 obtained using ANSYS is shown in fig.15 along with one obtained from experiment. The maximum load observed is 39.6kN in push and 38.2kN in pull respectively using ANSYS and 38.2kN in push and 36.6kN in pull respectively in the case of experiment and in both cases the specimen failed at 45 mm displacement.

The variation of collective energy dissipation and stiffness with displacement is shown in fig.16. The analytical value of total collective energy dissipation is 5147.63kN/mm and the stiffness degradation from 5.2kN/ mm to 0.33kN/mm. The experimental value of total collective energy dissipation for DD-T2L2 is 5250kNmm and the experimental stiffness of DD-T2L2 degraded from 5.4kN/mm to 0.42kN/ mm.



Fig.14 Collective Energy dissipation and stiffness vs. Displacement

Fig.15.Hysteresis behavior of Experiment and ANSYS specimen DD-T2L2

Fig.16.Collective Energy dissipation and stiffness vs Displacement

4. CONCLUSIONS The conclusions are presented based on the extensive experimental work and the numerical analysis.

The deficiency in collective energy dissipation in the case of non ductile reinforced beam column joint can be made good by ferrocement strengthening.

The composite materials ferrocement can be efficiently used for seismic retrofitting of reinforced beam column joint.

The specimens detailed as per IS: 13920:1993 with confining bars had improved ductility and energy absorption capacity than specimens detailed as per IS 456:2000. The displacement ductility is increased considerably for the non- conventionally detailed specimens.

The Energy carrying capacity of the retrofitted specimen is 66% more than that of the ductile control specimen.

Experimental investigation has been carried out and the test results show that the structural behavior of exterior beam column joint model

has been similar to that of analytical predicted one.

REFERENCES 1. Abhijit, M. and Mangesh Joshi, (2004), “FRPC

Reinforced Concrete Beam Column Joints under Cyclic Excitation”, Journal of composite structures, 70,185-199

2. Bindhu, K.R, Jaya, K.P. and Manickaselvam V.K. (2009), “Behavior and strength of exterior joint sub assemblages subjected to reversal loadings”, The Indian Concrete Journal, 09-20.

3. Bindu, K.R., and Jaya K.P., (2008), “Performance of exterior beam column joints with inclined bars at joints under cyclic load”, Journal of engineering and applied science 7, 591-597.

4. Costas, P. Antonopolulos and Thanasic C. triantafillou (2002), “Analysis of FRP-Strengthened RC Beam-Column Joints”, American Society of Civil Eng., 10, 1-11.

5. D. Kakaletsis (2011), “Comparison of CFRP and Alternative seismic retrofitting techniques for bare and infilled RC frames”, Journal of composites for construction, 565-577.

6. IS 10262: 2009 “Recommended guidelines for concrete mix design”, (Bureau of Indian Standards), New Delhi, India.

7. IS 13920: 1993 “Ductile detailing of reinforced Concrete structures subjected to Seismic forces - code of practice”, (Bureau of Indian Standards), New Delhi, India.



8. IS 456: 2000 “Plain and Reinforced concrete – Code of Practice”, (Bureau of Indian Standards), New Delhi, India.

9. Jamal S.M., Nabeela Abu, 2005, “Lateral Load Response of High Performance Fibre Reinforced Concrete Beam Column Joints”, Journal of construction and building materials, 19,500-508.

10. Maria J Favvata and Chris G. Karayannis (2014), “Influence of pinching effect of exterior joints on the seismic behaviour of RC frames”, Earthquakes and Struct., 6, 89-110.

11. Matthew J. Fisher and Halil sezen (2011), “Behavior of exterior reinforced concrete beam-column joints including a new reinforcement”, Struct. Eng. and Mech., 40, 867-883.

12. Pradip sarkar, Rajesh Agarwal, Devdas menon (2007) “Design of RC beam column joints under seismic loading” Journal of Structural Engineering, 33, 449-457.

13. Ramakrishna, R.V.S. and Ravindra V. (2012), “Experimental investigation on rehabilitation of reinforced cement concrete interior beam-column joints using CFRP and GFRP sheets”, International Journal of Engineering Science and Technology, 4 (3), 874-881.

14. Robert R.S and Arulraj P.G., (2010), “Experimental Investigation on Behavior of Reinforced Concrete Beam Column Joints Retrofitted with GFRP-AFRP Hybrid Wrapping”, International journal of civil and structural Engineering, 01(2), 245-253.

15. Said, A.M., Nehdi, M.L., Kehew, A.E., (2004), “Use of FRP for RC Frame in Seismic Zones, Evaluation of FRP Beam Column Joints Rehabilitation Techniques”, Journal of applied composite materials, 11, 205-226.

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17. Sushil S. Sharma, Urmil V. Dave and Himat Solanki (2013), “FRP Wrapping for RC Columns with varying Corner Radii”, Procedia Engineering, 51, 220 – 229.

18. Umut Akguzel and Stefano Pampanin (2002), “Assessment and Design Procedure for the Seismic Retrofit of Reinforced Concrete Beam-Column Joints using FRP Composite B structures subjected to seismic Forces”, J. Compos. Constr., 16, 21-34.

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