Brick Infill Research Articles

Experimental study on the behaviour of nonductile infilled RC frames strengthened with external mesh reinforcement and plaster composite

Abstract. The aim of this paper is to report on an experimental study about Turkish Earthquake Code on suggested strengthening method. The proposed method uses existing brick infill walls and the strengthening is done with the application of external mesh reinforcement and plaster. 5 nonductile 1/2 scaled, one bay, two storey RC specimens were tested under a reversed cyclic loading. The first two specimens were reference specimens and the other ones were strengthened with the proposed method. The specimens contained several design and construction mistakes such as low concrete quality and improper steel detailing. Strength, stiffness and storey drifts of the test specimens were measured. The results of the test on these frames were compared with the reference specimens. The effects of the reinforced mesh plaster application for strengthening on behaviour, strength, stiffness, failure mode and ductility of the specimens were investigated. Unexpected failure modes were observed during the testing and the results were summarized in this paper.

Experimental study for seismic retrofit of non‐seismic designed reinforced concrete structures

AbstractAn evaluation of seismic performance was conducted for a reinforced concrete (RC) structure designed without seismic considerations. The seismic performances of many existing structures are often inadequate based on the current seismic design codes, and it is sure that this is the general tendency in most countries.Six specimens were designed and constructed to simulate RC frames built in the 1980s, before the introduction of earthquake‐resistance design provisions in South Korea. The specimens were composed of one control specimen without any retrofit and five specimens retrofitted using wire‐bracing, brick infill wall, steel bracing (X‐ and K‐type) and corner gusset plate. All retrofitted specimens show significant increase in strength and ductility. The behaviours of each specimen are compared in the view of maximum strength, maximum moment, stiffness and energy dissipation capacity. Overall, efficiency analysis was also demonstrated in this study. Copyright © 2010 John Wiley & Sons, Ltd.

Seismic Strengthening with Precast Panels - Theoretical Approach

An economical, structurally effective and practically applicable seismic retrofitting technique has been developed on the basis of the principle of strengthening the existing hollow brick infill walls by using high strength precast concrete panels. The technique would not require evacuation of the building and would be applicable without causing much disturbance to the occupant. For this purpose, eighteen one-bay two-story reinforced concrete frames with hollow brick infill walls were tested under reversed cyclic lateral loading simulating earthquake. The specimens were strengthened by using six different types of precast concrete panels. In the present study, hollow brick infill walls strengthened by using high strength precast concrete panels were modeled once by means of equivalent diagonal struts and once as monolithic walls having an equivalent thickness. The experimental results were compared with the analytical results of the two approaches mentioned.

Use of steel fiber reinforced mortar for seismic strengthening

The objective of this research was to develop an economical, structurally effective, and practically applicable steel fiber reinforced mortar (SFRM) which could be applied onto the hollow brick infills of a reinforced concrete (RC) structure. Masonry walls were almost converted into strong and rigid infills with the application of SFRM. Two different mix proportions were produced with the composition of Portland cement, fine aggregate, water, and plasticizer or bonding agent as the chemical admixture. Tests were carried out to determine the optimum steel fiber content (1%, 2%, or 4% by volume) and to clarify the use of plasticizer or bonding agent in the mortar in the context of sticking ability, flexural, compressive, and adhesion strengths. As a result, mortar with plasticizer and 2% steel fiber (by volume) came out to be the optimum mortar mixture as strengthening material. The performance of RC frame strengthened with SFRM containing plasticizer and 2% steel fiber by volume was compared to those of the hollow brick infilled RC frame without strengthened mortar and the hollow brick infilled RC frame with reference mortar. It was observed that the specimen strengthened with the optimum mortar mix satisfied the target objectives of this study.

Preventing Collapse of Vulnerable R/C Buildings Using Wood Interlocking Blocks

This paper proposes a wood interlocking block infill to prevent vulnerable R/C buildings from collapsing, and discusses its viability through experimental and analytical investigations. A series of structural tests were performed using one-story, one-bay R/C frame specimens with/without installing the proposed infill to verify its contributions. As a result, the infill significantly improved the seismic performance, particularly axial resistance and ductility, of the overall frame. Moreover, an analytical study was also conducted to clarify the distinctive characteristics of the proposed infill. Probabilistic analyses were carried out focusing on a vulnerable R/C building damaged during the 2007 Sumatra, Indonesia earthquakes, which was investigated after the earthquakes by the authors. Comparing the probabilities of collapse for three cases-without infills, with typical brick infills, and with the proposed infills-an alternative concept to prevent building collapses and to save human lives was introduced.

Earthquake Casualties in Italy: The Blame Game

This note focuses on the true and perceived responsibilities for the recent earthquake losses in central Italy and on the status of seismic zoning in our country. The 6 April 2009, Mw 6.3 earthquake near L'Aquila (central Italy) was a standard Apenninic event: its magnitude, depth, and focal mechanism are consistent with the seismotectonic features of the area; historical earthquakes occurred in the same area with comparable characteristics, including a long-lasting sequence of foreshocks and aftershocks; strong ground motions seem to match well with existing predictive relationships; and the seismic hazard reaches the highest levels for Italy both on conventional and on time-dependent probabilistic maps. Despite the fact that a seismic building code was adopted in this area as early as 1927, the unacceptable death toll of the earthquake (around 300 victims) is largely to be blamed on the poor quality of construction. As with past earthquakes, severe damage and collapse mainly affected old buildings (unreinforced masonry or stone buildings); but surprisingly, a number of multistory buildings of relatively new construction (reinforced concrete frame buildings with brick infill) were destroyed too: among these, L'Aquila's main hospital (finished in 2000) and the university's dormitory (built in the late 1970s). As with past earthquakes, severe damage and collapse mainly affected old buildings (unreinforced masonry or stone buildings); but surprisingly, a number of multistory buildings of relatively new construction (reinforced concrete frame …

The Pisco (Peru) earthquake of 15 August 2007

The Mw 8.0 Pisco earthquake struck at 6.40pm local time with an epicentre offshore about 150 km south of Lima. At least 519 people were killed, and over 1,300 injured. Over 38,000 homes were destroyed and more than 100,000 were made homeless. 14 hospitals were destroyed and many other facilities damaged. The city of Pisco was worst affected with serious damage to the majority of adobe buildings. Other cities and towns nearby suffered similar damage to a lesser extent, depending on the distance from the epicentre. The capital Lima was not seriously affected, although there was some minor damage to buildings.
 Strong ground motions were felt for over two minutes. In this subduction earthquake a tsunami was generated and affected tens of kilometres of coast.
 The New Zealand Society for Earthquake Engineering Society (NZSEE) sent a 6-person reconnaissance team to Peru. The team spent three days in Lima meeting with key authorities and four days in the field observing some of the earthquake-affected area. This report describes the team’s observations and comments on the implications for earthquake engineering practice.
 Highlights of the event in the eyes of the team were:
 
 The long duration of the event – over 2 minutes of strong shaking
 The unique geotechnical context – no rainfall and sandy soils
 Significant liquefaction damage to roads and buildings
 Poor performance of adobe construction
 Generally good performance of reinforced concrete brick infill – but there were major collapses.
 Good performance of some unreinforced masonry buildings
 Widespread use of shear walls in major buildings in Lima
 Engineered structures generally performed well
 Damage to parts of Pan American Highway due to liquefaction
 Minimal damage to a major steel mill, designed to international standards
 Collapse and/or overload of telecom systems for up to four hours following the event, isolating Pisco and Ica
 Water and waste water systems and storage were seriously affected in Pisco, and significantly in Ica
 Port St Martin, serving Pisco, was seriously damaged but functional
 Coordination of overseas / international aid needs careful consideration as part of response planning.
 Management of response resources is critical.
 There were significant tsunami effects which were variable in height up to 10 metres.
 Relatively minor damage to architectural finishes and building services can render hospitals non-functional.
 Survival of industrial facilities was important in reducing social impact by saving jobs.
 The best of Peruvian earthquake engineering is international standard.
 The development of earthquake-resistant standards in schools over the last three decades has paid dividends with modern designs performing well.

Experimental Investigation on Three Dimensional RC Infilled Frame - RC Plane Frame Interactions With Slab for Seismic Resistance

Experimental investigation was planned and conducted to study the influence of brick masonry infill and slab in a three-dimensional reinforced cement concrete frame. In this study, one-fifth scale 3D R.C frame representing single story, three bays with central bay brick infill at the sides and a long single bay without infill in the middle of the frame along loading direction and two numbers of two bays at the edges without infill and two numbers of single bay without infill in the transverse direction with slab, has been taken for experimental investigation and the available methods of theoretical analysis for the frames have been carried out. Totally ten columns, eight columns in both ends of the frame along loading direction and two columns in middle along loading direction, were constructed in the frame. Until the cracks developed in infills, the contribution of the infill to both lateral stiffness and strength is very significant. The infill and slab also changes the dynamic characteristics of the frame. The change in lateral stiffness, strength, ductility and natural period of the framed structure due to the presence of infills and slab change the behavior of the building under seismic action. The object of this study was to investigate the behavior of such three dimensional RC infilled frames with slab under seismic loads. Analytical works was done to understand the strength and behavior of these types of frames.

Component damage functions for reinforced concrete frame structures

Displacement-based damage functions for the components of reinforced concrete (RC) moment resisting frames have been developed. RC columns, beams and brick infills were considered in this study as the structural elements that contribute to the seismic behavior of RC moment resisting frames. Finite element analyses were carried out on RC columns and beams to investigate effects of their material and geometrical properties on the behavior of these elements, and also to develop the damage functions. The independent parameter used in the damage functions developed for RC columns was the interstorey drift ratio, while rotation was used as the main parameter to evaluate damage in RC beams. The equivalent strut models available in the literature were used to determine the parameters affecting the damageability of brick infills and to develop drift-based damage functions. Additional damage functions for shear critical RC columns and beams were also developed. The damage functions proposed were validated via comparison to the test results available in the literature. These damage functions are proposed to be used for the seismic performance evaluation of RC moment resisting frames.

Analysis and design of FRP composites for seismic retrofit of infill walls in reinforced concrete frames

There is an urgent need to retrofit deficient mid-rise reinforced concrete (RC) frame buildings in Turkey. For this purpose, an efficient FRP retrofit scheme has been developed previously, in which hollow clay brick infill walls can be utilized as lateral load resisting elements after retrofitting. The main premise of this practical retrofit scheme was to limit inter-storey deformations by FRP strengthened infill walls that are integrated to the boundary frame members by means of FRP anchors. Based on the analytical model that was previously verified extensively by comparison with test results, a simplified model was proposed for use in displacement based design of FRPs for deficient RC frame buildings. FRP retrofit design and analysis of an actual deficient RC building located in Istanbul are presented herein both for the local design spectrum and Duzce ground motion. It was observed that the FRP retrofit reduced the damage induced to deficient columns by controlling story deformations. In this way, it was possible to satisfy the collapse prevention performance state in an efficient and economical manner.

Effects of infill walls and floor diaphragms on the dynamic characteristics of a narrow-rectangle building

Most buildings in Singapore are lightly reinforced concrete structures, which are mainly designed for gravity loading only, because Singapore is an island country located in a low-to-moderate seismic region. The dynamic properties of a typical high-rise residential building with a long, narrow rectangular floor plan are studied using both experimental and numerical methods. The effects of the brick infill walls and the flexible diaphragms on the dynamic characteristics of the building are discussed in detail. The results from the ambient vibration tests are correlated with the numerical results of three different finite element models with different levels of sophistication. They include a bare frame model, a frame model with brick infill walls, and a frame model with both brick infill walls and flexible diaphragms. The dynamic properties of the third model match very well with the measured results in terms of both the natural frequencies and the mode shapes. The correlation results demonstrate the respective effects of the brick infill walls and the flexible diaphragms on the dynamic characteristics of the narrow-rectangle building structure. Copyright © 2006 John Wiley & Sons, Ltd.

Seismic response of traditional buildings of Lefkas Island, Greece

This paper deals with the seismic response of the traditional buildings of Lefkas (also called ‘Lefkada’) Island in western Greece. These structures, with two up to four storeys, are met mainly in the old town of Lefkas, the capital of the island. The special structural characteristic of the traditional buildings of Lefkas (that is the issue of this article) is the dual load-carrying system used on ground floor level to handle vertical loads and seismic actions. The first main load-carrying system consists of single-storey stone masonry walls, while the second main load-carrying system consists of multistorey wooden frames at the inner perimeter of the ground-floor masonry walls. Therefore, the load-bearing system of the upper storeys, over the ground floor, consists of a wooden 3D frame with diagonal trusses that are infilled by walls of bricks and lime mortar. There is, also, a tiled wooden roof. During the earthquake of August 14th, 2003 ( M = 6.2 ) , partial collapse of the masonry walls took place in some cases at the low storey and some cracks around the openings were observed. In the upper floors, the load-bearing wooden frames did not suffer damage, but the brick infill cracked and out-of-plane falls were observed. In this paper, the analytical investigation of the seismic behaviour of such structures is developed, the identification of the main way of vibration of these systems is achieved, and both the explanation of the observed damages and the interpretation of the reasons for the development of these damages are performed. Finally, the results of a representative numerical model of a typical traditional building—from a series of examined models—with dual bearing system are presented and discussed, using as base excitation the two horizontal recorded components of the main earthquake ground motion that took place on August 14th, 2003, at Lefkas town, Greece.

EFFECT OF MASONRY INFILL FOR REDUCING THE SWAY OF RC FRAME USING FINITE ELEMENT MODELING

Sway of reinforced concrete (RC) frame subjected to lateral load is an important design parameter from serviceability point of view. In Bangladesh, brick infills are used as exterior walls and partitions. Present code of practice does not include provision of taking into consideration the structural effect of infill in multi-storeyed building construction. Yet, the presence of infill increases the lateral stiffness of the structure and reduces the value of sway. For this, if it is taken into consideration, the resulting structure will be economic. Thus, there is a scope of investigation on the importance of infill in a frame structure. In this paper, an investigation based on finite element modeling of reinforced concrete frame in the presence of masonry infill subjected to lateral loads is carried out to study the sway behavior of RC frame. The frame is modeled as a two-dimensional structure using two dimensional frame elements to model beam and columns, and the in-plane stiffness of brick wall, contribu...

Seismic-damage quantification for brick infills of RC frames

The paper is devoted to evaluate indices at the element level, to be applied together with member-type models, in representing different damage stages for nonstructural brick infills. Interstorey drift, stiffness-based indices and response-based indices are correlated to the visible damage exhibited by the filler walls of one-storey one-bay half-scale specimens, subjected to pseudodynamic tests. Damage measures derived from both experimental results and numerical simulations are presented. Finally, a modified stiffness-based index reflects the visual damage to a satisfactory degree of accuracy.

ANALYTICAL MODELS FOR BRICK MASONRY INFILLED R/C FRAMES UNDER LATERAL LOADING

Proposed in this paper are two analytical models for predicting the inelastic response of unreinforced brick masonry infills in reinforced concrete frames subjected to mono-tonic and reversed cyclic loading. The first model is based on the traditional diagonal strut concept, while the second one is a simple isoparametric element with shear deformation only. All the essential characteristics of the hysteretic behaviour of the panel, including strength and stiffness degradation, pinching and slippage, are explicitly taken into account. The models are implemented in a general-purpose program for the inelastic time-history analysis of structures, and are used for studying the seismic behaviour of typical multistorey frames with various arrangements of infill panels, including structures with an open ground storey. The results of the analysis are in agreement with both experimentally observed behaviour and with experience regarding seismically damaged buildings.