# Study on Performance of Infilled Wall in an RC-Framed Structure Using a Reinforcing Band

Authors: P. Jagadeesan; N. Sudharsan; S.M. Subash; Pradeep Thirumoorthy; B. Sugumaran; Jabar Abdul Bari; R. Vetturayasudharsanan; D. Ambika; K. Sharmiladevi; Kathiresan Karuppanan
Journal: Advances in Materials Science and Engineering
 (2022)

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## Abstract

Infilled wall is a primary structure which is used in a multistorey RC-framed structure. It is not designed like structural elements, but it is subjected to structural load and response as a heavily damaged element into the building. The main problem of an infilled wall is not actively utilizing in the framed structure and it is not interacted with frame elements. The objective of research is to utilize the infilled wall in the RC-framed structure by improving its performance of behavior. Here, two different types of brick masonry like Autoclaved concrete and clay brick masonry were used as the infilled wall in an RC-framed structure. A singly bay and single storey RC framed structure was cast and tested under a 1/10th scale model by diagonal compressive loading. The specimen was subjected to static loading by a universal testing machine. Infilled wall is weak in tension, so a reinforcing band was used to improve the performance like load carrying capacity, stiffness, ductility, and energy dissipation capacity. Based on the results of the experimental study, it is found that reinforcing band with the infilled wall gives better behavior of the RC-framed structure.


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## Body

## 1. Introduction

At present, the development of tall construction is necessary to avoid more utilization of land area for building up the structure in the urban community [1, 2]. At the same time, the effects of earthquake in tall structures have been severely damaged due to out of uncontrolled lateral displacements and it makes serious damages to the structural elements [3, 4]. Structural construction with infilled frames has induces more trouble with the recommended resources of lateral load [5, 6]. Normally, all type of framed structures consisted of structural and nonstructural elements [7, 8]. In that, masonry infilled walls are recommended as a nonstructural member for separating the rooms and living can be proficiently used in combination with a framing system [9, 10]. Although, these nonstructural boundaries of unreinforced masonry walls are imperfect in shear and tensile strength and it is brittle mannerism, inconceivable damages are exposed at time of loading [11, 12].The lateral strength of infilled frames with variation of infill wall thickness and it was proved that these frames more lateral strength than bare frame [13, 14].When the infilled wall is subjected to in-plane loading, it generates strut action and it leads to the failure between masonry and frame elements [12, 15]. Therefore, the composite motion of the infilling materials like a traditional brick wall with the predominant frame can be examined. It [4, 16] has been studied that the lateral strength of the infill frame is predominately higher than the bare frame [17, 18]. This study is conventionally showing the strength and stiffness of the brick partitions furnished for encouraged aspects, in shape at the equal time with economy [19, 20]. During the design and analysis of the reinforced concrete-framed structures, the infilled wall is ignored due to its highly nonlinear nature [21]. Also, it is difficult to stimulate and interact with the surrounding frame when the structure is subjected to lateral loads induced by earthquake ground motions [19, 22]. It is necessary to investigate the interaction between RC-framed structures and infill wall panels and large numbers of experimental works with analytical investigation were conducted [23, 24]. The presence of the infill wall increases the stiffness and the strength of the framed building but the infill wall has a negative impact on the integrity of some building due to composite action, irregularities, and soft storey mechanism [16, 25].


## 2. Objective of Research

The objective of research is to study the behavior of interaction between a RC frame and an infilled wall under static loading. In this work, the different type of specimens was prepared in the form of a single bay single storey rectangular infilled RC frame.The focus of this investigation is to observe the strength, ductility, stiffness, energy dissipation capacity, and failure mechanism of these specimens [26]. Finally, the results were compared with each other and suitable strengthened infilled wall is identified. Thus, it improves the interaction between the infilled wall and RC frame elements.


## 3. Methodology of Research Work

The performance of RC frame with miscellaneous types of an infilled wall was examined under an experimental investigation programme. The type of RC frames has cast as a single bay single storey frame with different kinds of the infilled wall by following ways.Rectangular RC frame without infill (BF)Rectangular RC frame with clay brick masonry (IF-CBM)Rectangular RC frame with Autoclave aerated concrete brick masonry (IF-ABM)Rectangular RC frame with reinforced clay brick masonry (IF-RCBM)Rectangular RC frame with reinforced Autoclave aerated concrete brick masonry (IF-RABM)The specimens are modeled as 1/10 scale from prototype structure and dimension of infilled RC frames were fabricated in uniform size and it is tabulated in Table1.Table 1
Dimension details of specimens.
Frame designationC/S dimensions (mm)Main reinforcementBreadthDepthBF60504 No’s, 4 mmϕIF-CBM60504 No’s, 4 mmϕIF-ABM60504 No’s, 4 mmϕIF-RCBM60504 No’s, 4 mmϕIF-RABM60504 No’s, 4 mmϕIn general, horizontal loads are acting at a beam-column joint and this load is transferred as diagonal load or in-plane load to the infilled wall. In this experimental investigation, the lateral load was applied in the form of diagonal load at beam-column joints. Here, a single bay single storey interior panel was selected, and it was rotated diagonally in a vertical plane and in-plane load was given in the form of vertical compressive load. When applying this load, a mild steel plate was provided at the beam-column joint to distribute the load from frame elements to the infilled wall.


## 4. Material Specifications

### 4.1. Material Requirements

53 Grade of ordinary Portland cement was used. The cement was in standard gunny bags and transferred later to airtight steel drums to avoid deterioration of quality. River sand was used for all specimens for experiment work was sieved through a 4.75 mm sieve [27]. The stones were used for all specimens is medium gravel for experiment work and it was sieved through a 10 mm sieve. To construct the RC frame, a combination of the mild steel plate and wooden mould was especially fabricated for the modeling or casting of specimens. Each component of the mould is in a separate segment and the utilization of a bolted joint can effortlessly configure it. The mould is attached with a wooden platform to obtain smoothness in the specimen. The geometry detail of mould specimen is given in Figure 1.Figure 1
Specimen mould (all dimensions are in mm).The specimens are made up of infilled reinforced concrete structures and it consists of reinforcement, concrete, and brick masonry infilled walls [28]. The size of main reinforcement was 4 mm in diameter. The reinforcement arrangement of specimen is shown in Figure 2. For concrete, M20 grade of concrete was designed by design mix proportions. In the infilled masonry wall, first class clay bricks of size 190 mm × 90 mm × 90 mm were used for constructing brick masonry work and it is the prototype under the dimensions of 60 mm × 30 mm × 30 mm was used as infilled wall. Similarly, autoclave-aerated concrete block was used as the masonry structure for another type of specimen with a size of 60 mm × 30 mm × 30 mm.Figure 2
Reinforcement details of the frame.


### 4.2. Casting and Curing of the Frame

The mould is arranged on a clean, flat, and nonabsorbent surface. The inner and bottom of the mould were well oiled to prevent the specimen from sticking on it. The steel reinforcement of the frame is placed in the mould with the proper side and bottom clear cover. In the casting of the frame, the concrete was filled in the mould in three layers. In each layer, the specimen was compacted under the table vibrator. The mould was dismantled after 24 hours; then, the specimen was placed in water for curing. The frame was cured for 28 days [29]. Figure 3 shows the casting of infilled RC frame and reinforcing band also arranged.Figure 3
Casting of the infilled RC frame.


### 4.3. Testing Arrangements

Before the testing, the specimen was dried to avoid moisture in concrete. After the specimens were whitewashed, the specimen was arranged in the universal testing machine (UTM) to test the performance of the structure. The loading arrangement of the infilled RC frame specimen is shown in Figure4. Here, UTM is available with electronic and computerized functioning, and it is based on a forced based system and strain was also measured. A singly bay single storey interior frame was cast and load is applied at in-plane loading in the form of diagonal load. The specimen was subjected to uniform rate of loading and load vs deflection was recorded [30].Figure 4
Loading arrangement of the specimen.


## 4.1. Material Requirements

53 Grade of ordinary Portland cement was used. The cement was in standard gunny bags and transferred later to airtight steel drums to avoid deterioration of quality. River sand was used for all specimens for experiment work was sieved through a 4.75 mm sieve [27]. The stones were used for all specimens is medium gravel for experiment work and it was sieved through a 10 mm sieve. To construct the RC frame, a combination of the mild steel plate and wooden mould was especially fabricated for the modeling or casting of specimens. Each component of the mould is in a separate segment and the utilization of a bolted joint can effortlessly configure it. The mould is attached with a wooden platform to obtain smoothness in the specimen. The geometry detail of mould specimen is given in Figure 1.Figure 1
Specimen mould (all dimensions are in mm).The specimens are made up of infilled reinforced concrete structures and it consists of reinforcement, concrete, and brick masonry infilled walls [28]. The size of main reinforcement was 4 mm in diameter. The reinforcement arrangement of specimen is shown in Figure 2. For concrete, M20 grade of concrete was designed by design mix proportions. In the infilled masonry wall, first class clay bricks of size 190 mm × 90 mm × 90 mm were used for constructing brick masonry work and it is the prototype under the dimensions of 60 mm × 30 mm × 30 mm was used as infilled wall. Similarly, autoclave-aerated concrete block was used as the masonry structure for another type of specimen with a size of 60 mm × 30 mm × 30 mm.Figure 2
Reinforcement details of the frame.


## 4.2. Casting and Curing of the Frame

The mould is arranged on a clean, flat, and nonabsorbent surface. The inner and bottom of the mould were well oiled to prevent the specimen from sticking on it. The steel reinforcement of the frame is placed in the mould with the proper side and bottom clear cover. In the casting of the frame, the concrete was filled in the mould in three layers. In each layer, the specimen was compacted under the table vibrator. The mould was dismantled after 24 hours; then, the specimen was placed in water for curing. The frame was cured for 28 days [29]. Figure 3 shows the casting of infilled RC frame and reinforcing band also arranged.Figure 3
Casting of the infilled RC frame.


## 4.3. Testing Arrangements

Before the testing, the specimen was dried to avoid moisture in concrete. After the specimens were whitewashed, the specimen was arranged in the universal testing machine (UTM) to test the performance of the structure. The loading arrangement of the infilled RC frame specimen is shown in Figure4. Here, UTM is available with electronic and computerized functioning, and it is based on a forced based system and strain was also measured. A singly bay single storey interior frame was cast and load is applied at in-plane loading in the form of diagonal load. The specimen was subjected to uniform rate of loading and load vs deflection was recorded [30].Figure 4
Loading arrangement of the specimen.


## 5. Result and Discussion

### 5.1. Load-Deflection Behaviour

The utilization of the infilled wall in an RC-framed structure influences strength and serviceability of structural members. The load-deflection curve is to understand the performance of load carrying capacity, stiffness, ductility, and energy dissipation capacity of the infilled RC framed-structure. Here, different kinds of the masonry wall were used in the infilled wall and it makes significant usage of framed structure. Normally, the infilled wall is weak in tension and it is not effective to carry in flexure and shear. Adding of reinforcement band in infilled wall enhances the serviceability conditions in the infilled wall. From Figure5, it can be understood that the bare frame specimen has more deflection when compared with the infilled RC frame because of stiffness and this stiffness does not permit the deflection in the infilled RC frame. In a multistorey framed structure, masonry wall is necessary to partition and suppose to carry the load from structure. Therefore, it is significant to improve the deflection in masonry wall by introducing the reinforcing band in between a layer of the masonry structure. Figure 5 shows that specimen IF-RCBM and IF-RABM are more effective in deflection limit when compared with that of IF-CBM and IF-ABM specimens, respectively.Figure 5
Load-deflection curve.


### 5.2. Ultimate Load Carrying Capacity

In this investigation, two different kinds of masonry structure were used as the infilled wall such as brick masonry wall and autoclave-aerated concrete brick masonry wall. These masonry structures were strengthened with a reinforcing band because it does not carry tensile strength. When compared with an ordinary masonry infilled wall, reinforced masonry wall attains more ultimate load carrying capacity. Figure6 shows ultimate load carrying capacity of all specimens. From Figure 6, it is specified that autoclave-aerated concrete brick masonry provide comfortable strength against bare frame and ordinary brick masonry.Figure 6
Ultimate load carrying capacity of specimens.


### 5.3. Initial Stiffness

Initial stiffness means force induced due to unit displacement at the time of yielding of structural member (Figure7). When compared with bare frame, specimen IF-CBM and IF-ABM produce more initial stiffness because of the infilled wall is not permitted the deflection in RC-framed structures. Infilled RC frame has high stiffness value except IF-RABM specimen. Thus, reinforcing band allows yielding with maximum load carrying capacity.Figure 7
Initial stiffness of specimen.


### 5.4. Ductility

Ductility is a significant factor to understand the flexible behaviour of the structure. It is the ratio between ultimate deflection to yield deflection. Figure8 shows the ductility of various specimens. From Figure 8, it is understood that the ductility of infilled RC frame is same with various types of masonry infilled walls. However, reinforced masonry infilled RC frame attains more ductility when compared to other specimens. It denotes that reinforcing band improves the ductility in the infilled wall.Figure 8
Ductility of specimen.


### 5.5. Energy Dissipation Capacity

The principle of energy dissipation capacity is simulating the energy released by structural elements when a member is subjected to loading. Here, in this investigation, the area enclosed under the load deflection curve is noted as energy absorption capacity. From Figure9, it is clearly indicated that the reinforced infilled RC frame has more energy capacity when compared to the ordinary infilled RC frame. After yielding the reinforcing band, it allows deformation up to the maximum limit. The energy capacity of reinforcing infilled wall is 3.19 times more than an ordinary infilled wall. Figure 9 refers to the ordinary infilled RC frame and bare frame has similarly energy dissipation capacity.Figure 9
Energy dissipation capacity of specimen.


### 5.6. Failure Mechanism

The study and analysis of the failure pattern is significant to know about the performance of the structure. Generally, the infilled RC framed structure is subjected to different kinds of failure pattern in the structure. Due to in-plane diagonal loading, compressive force is developed along the loading direction and opposite direction tension force is induced. Therefore, the member reflects shortened and elongated along the diagonal length of RC frame structure. Figure10(a) represents the failure pattern of RC bare frame. Besides, beam-column joint failure also happened during testing. Normally, the infilled wall is provided in between frame members and when it is subjected to loading, a diagonal crack occurs (Figure 10(b)). This type of failure induces a sudden debris of the infilled wall and load also not distributed evenly to infilled wall (Figure 10(c)). When comparing with an autoclave concrete block, brick masonry wall is weak in strength and it induces spalling of the brick element (Figure 10(d)). From the analysis of failure pattern of the infilled RC frame, it is understood that there is not much interaction between infilled wall and frame, and it leads to failure of bedding joints in the specimens. But using of this reinforcement band, it enhanced the interaction between infilled wall and frame.Figure 10
(a) Bare frame. (b) Failure of IF-CBM. (c) Failure of IF-CBM. (d) Failure of IF-RABM.
(a)(b)(c)(d)


## 5.1. Load-Deflection Behaviour

The utilization of the infilled wall in an RC-framed structure influences strength and serviceability of structural members. The load-deflection curve is to understand the performance of load carrying capacity, stiffness, ductility, and energy dissipation capacity of the infilled RC framed-structure. Here, different kinds of the masonry wall were used in the infilled wall and it makes significant usage of framed structure. Normally, the infilled wall is weak in tension and it is not effective to carry in flexure and shear. Adding of reinforcement band in infilled wall enhances the serviceability conditions in the infilled wall. From Figure5, it can be understood that the bare frame specimen has more deflection when compared with the infilled RC frame because of stiffness and this stiffness does not permit the deflection in the infilled RC frame. In a multistorey framed structure, masonry wall is necessary to partition and suppose to carry the load from structure. Therefore, it is significant to improve the deflection in masonry wall by introducing the reinforcing band in between a layer of the masonry structure. Figure 5 shows that specimen IF-RCBM and IF-RABM are more effective in deflection limit when compared with that of IF-CBM and IF-ABM specimens, respectively.Figure 5
Load-deflection curve.


## 5.2. Ultimate Load Carrying Capacity

In this investigation, two different kinds of masonry structure were used as the infilled wall such as brick masonry wall and autoclave-aerated concrete brick masonry wall. These masonry structures were strengthened with a reinforcing band because it does not carry tensile strength. When compared with an ordinary masonry infilled wall, reinforced masonry wall attains more ultimate load carrying capacity. Figure6 shows ultimate load carrying capacity of all specimens. From Figure 6, it is specified that autoclave-aerated concrete brick masonry provide comfortable strength against bare frame and ordinary brick masonry.Figure 6
Ultimate load carrying capacity of specimens.


## 5.3. Initial Stiffness

Initial stiffness means force induced due to unit displacement at the time of yielding of structural member (Figure7). When compared with bare frame, specimen IF-CBM and IF-ABM produce more initial stiffness because of the infilled wall is not permitted the deflection in RC-framed structures. Infilled RC frame has high stiffness value except IF-RABM specimen. Thus, reinforcing band allows yielding with maximum load carrying capacity.Figure 7
Initial stiffness of specimen.


## 5.4. Ductility

Ductility is a significant factor to understand the flexible behaviour of the structure. It is the ratio between ultimate deflection to yield deflection. Figure8 shows the ductility of various specimens. From Figure 8, it is understood that the ductility of infilled RC frame is same with various types of masonry infilled walls. However, reinforced masonry infilled RC frame attains more ductility when compared to other specimens. It denotes that reinforcing band improves the ductility in the infilled wall.Figure 8
Ductility of specimen.


## 5.5. Energy Dissipation Capacity

The principle of energy dissipation capacity is simulating the energy released by structural elements when a member is subjected to loading. Here, in this investigation, the area enclosed under the load deflection curve is noted as energy absorption capacity. From Figure9, it is clearly indicated that the reinforced infilled RC frame has more energy capacity when compared to the ordinary infilled RC frame. After yielding the reinforcing band, it allows deformation up to the maximum limit. The energy capacity of reinforcing infilled wall is 3.19 times more than an ordinary infilled wall. Figure 9 refers to the ordinary infilled RC frame and bare frame has similarly energy dissipation capacity.Figure 9
Energy dissipation capacity of specimen.


## 5.6. Failure Mechanism

The study and analysis of the failure pattern is significant to know about the performance of the structure. Generally, the infilled RC framed structure is subjected to different kinds of failure pattern in the structure. Due to in-plane diagonal loading, compressive force is developed along the loading direction and opposite direction tension force is induced. Therefore, the member reflects shortened and elongated along the diagonal length of RC frame structure. Figure10(a) represents the failure pattern of RC bare frame. Besides, beam-column joint failure also happened during testing. Normally, the infilled wall is provided in between frame members and when it is subjected to loading, a diagonal crack occurs (Figure 10(b)). This type of failure induces a sudden debris of the infilled wall and load also not distributed evenly to infilled wall (Figure 10(c)). When comparing with an autoclave concrete block, brick masonry wall is weak in strength and it induces spalling of the brick element (Figure 10(d)). From the analysis of failure pattern of the infilled RC frame, it is understood that there is not much interaction between infilled wall and frame, and it leads to failure of bedding joints in the specimens. But using of this reinforcement band, it enhanced the interaction between infilled wall and frame.Figure 10
(a) Bare frame. (b) Failure of IF-CBM. (c) Failure of IF-CBM. (d) Failure of IF-RABM.
(a)(b)(c)(d)


## 6. Conclusion

Infilled wall is a mandatory nonstructural element for the framed structure but this element is not designed. When the structure is subjected to loading, infilled wall carries a load partially itself and it induces a major damage suddenly. The conclusion of this concern is to introduce the reinforcing band to infilled wall to improve the performance of structure testing with different kinds of infilled wall. In this research work, two types of infilled wall like clay brick masonry and autoclave-aerated concrete brick masonry were used. The conclusion drawn based on the experimental investigation on a one-tenth model scale of the RC frame with infilled under static loading are discussed below.(i)
The ultimate load carrying capacity of the frame with reinforced autoclave-aerated concrete brick masonry is 25.96% greater than that of the frame with ordinary autoclave-aerated concrete brick masonry.(ii)
The ultimate load carrying capacity of the frame with reinforced autoclave-aerated concrete brick masonry is 21.87% greater than that of the frame with reinforced clay brick masonry.(iii)
The initial stiffness of the frame with reinforced clay brick masonry is 33.80% greater than that of the frame with reinforced autoclave-aerated concrete brick masonry.(iv)
The initial stiffness of the frame with reinforced clay brick masonry is 49.64% greater than that frame with clay brick masonry.(v)
The ductility for the frame with reinforced clay brick masonry is 29.34% greater than that of the frame with autoclave-aerated brick masonry.(vi)
The ductility for the frame with reinforced clay brick masonry is 31.24% greater than that of the frame with ordinary clay brick masonry.(vii)
The energy dissipation capacity for the frame with reinforced clay brick masonry is 1.11 times greater than that of the frame with clay brick masonry.(viii)
The energy dissipation capacity for the frame with reinforced clay brick masonry is 3.19 times greater than that of the frame with ordinary clay brick masonry.(ix)
Finally, it is proved that a reinforcing band in the infilled wall enhances the structural behavior of the RC-framed structure.



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*Source: 8643959-2022-09-06.xml*