Masonry Infill Walls Research Articles

Damage Estimation of Full-Scale Infilled RC Frames under Pseudo-Dynamic Excitation by Means of Output-Only Modal Identification

To assess the health condition of structures and infrastructure during their service lives, continuous vibration-based monitoring represents a viable and cost-effective solution. Model updating and digital twins are increasingly adopted for damage detection. However, significant gaps and uncertainties in damage quantification still arise. This work presents original data from output-only modal identification tests on full-scale, two-storey reinforced concrete (RC) frames subjected to pseudo-dynamic loading to simulate seismic damage. The frames are tested with two masonry infill wall configurations with three-sided and four-sided boundary conditions, and the observed seismic damage is correlated to a damage scale. Output-only modal identification tests are performed before and after testing to catch variations in modal properties due to observed damage. Experimental data are used to build a refined finite element model able to reliably simulate the static and dynamic performance of the infilled RC frames before and after damage. The model allowed for the further assessment of the variation in natural frequencies of tested specimens at different earthquake intensities, the correlation of such variations to damage levels, and identification of the contribution of structural and non-structural components to the overall frequency variation.

Numerical simulation of RC-masonry infill wall system strengthened with textile reinforced concrete

Masonry walls are generally considered non-load-bearing elements in most concrete or steel-framed structures. Being a heterogeneous structure, the masonry system effectively enhances the strength and lateral stiffness of the overall panel when subjected to horizontal forces. But the recent unsatisfactory performance of unreinforced Masonry Infill Walls (MIW) during in-plane seismic loading has caught the attention of many researchers for the last few years. To overcome these detrimental effects, strengthening the MIW frame is considered the best procedure to enhance the horizontal load-carrying capability of the system. Numerous studies evaluating various parameters affecting the behaviour of MIW were conducted using Fiber Reinforced Cementitious Material (FRCM) as a strengthening material. This paper conducted a validation study that includes numerical simulation of the experimental research carried out at Wellington Institute of Technology in which nine 2:3 scaled single bay and single story Reinforced Concrete Frame with Masonry Infills (RCFMI) specimens strengthened with different fibers (basalt, carbon, and glass) of FRCM was tested under in-plane seismic/cyclic loads. The study went into detail on creating a numerical model replicating the non-linear structural cyclic behaviour of an infill wall bound by a reinforced Concrete frame and subjected to displacement-controlled in-plane lateral stress. The numerical analysis was performed in the Finite Element Method (FEM) programme ABAQUS using a streamlined micro-model approach. To simulate the non-linear behaviour of the masonry blocks and concrete, the Concrete Damage Plasticity (CDP) model was employed. The tested specimen was retrofitted with glass fiber grid diagonal bands, each with a width equal to 1/6 of the infill diagonal length. This analysis was used to create the numerical model. The validation demonstrated that the numerical model could faithfully simulate the behaviour and forecast the strength of masonry infill walls with RC frames. The findings of the observations are explained in the form of load–displacement hysteresis loops and excursion curves. The numerical results demonstrate excellent agreement with the experimental data, a significant impact of FRCM on the system's dynamic behaviour, and an improvement in MIW effectiveness with FRCM under cyclic loading is observed.

Investigation on the seismic performance of the masonry infill wall with damping layer joint

Aimed at improving the seismic performance of the traditional masonry infill wall (MIW), an innovative configuration called Damped Masonry Infill Wall (DMIW) is developed through subdividing the MIW horizontally and introducing damping layer joint (DLJ) into the wall. In order to verify the feasibility and the seismic performance of DMIW, the optimized material used as DLJ was determined among four types of materials via the shear-hysteretic test firstly. Then, a quasi-static test was performed to investigate the seismic performance of 1:2 scaled RC frame specimens with DMIW and traditional MIW, in terms of damage pattern, seismic parameters, shear deformation characteristics of DLJ. The results show that the modified asphalt waterproof (MAW) product, APF-500 (also labelled No.1 MAW in this study), is the optimized material used for DLJ among other three tested material. The expected working mechanism of DMIW that the shear deformation of the wall concentrates in the DLJs is able to be realized by using the optimized DLJ material. Also, it proves that DMIW is capable of presenting a prominent reduction of damage level and significant decrease of the lateral force and stiffness. It is anticipated that the detrimental effect of traditional MIW on the seismic performance of the frame structure can be avoided by adopting DMIW. Furthermore, a fitted equation of the relationship between the maximum shear deformation demand of DLJ and the lateral deformation of the RC frame is developed for determining the minimum thickness of DLJ in the case where DMIW has three masonry units.

Development of Fragility Curves for Reinforced-Concrete Building with Masonry Infilled Wall under Tsunami

A tsunami is a natural disaster that destroys structures and kills many lives in many countries in the world. A risk assessment of the building under a tsunami loading is thus essential to evaluate the damage and minimize potential loss. A crucial tool in risk assessment is the fragility curve. Most building fragility curves for tsunami force were developed using survey building damaged data. This research proposed a method for developing fragility curves under tsunami loading based on the analytical building model data. In the development, the generic building was a one-story reinforced-concrete building with masonry-infilled walls constructed from the structural index, popularly built as residential buildings along the west coast of southern Thailand. Three damage levels were investigated: damage in masonry infill walls, damage in primary structures, and collapses. The masonry infill wall was modeled using multisprings to represent the load-bearing behavior due to tsunami with a hydrodynamic pattern. The fragility curves were developed using the maximum likelihood method and considering the uncertainty due to masonry infill wall type, tsunami flow direction, and tsunami flow velocity. The developed fragility curve agrees well with the empirical tsunami fragility curve of a one-story reinforced-concrete building damage data in Thailand from the 2004 Tsunami. The developed fragility functions could be adopted for assessing tsunami risk assessment and disaster mitigation for similar structures against different tsunami scenarios in the future.

Experimental and finite element analysis: Out-of-plane mechanical performance of infill walls with flexible connection

Flexible connection between the wall and the frame can improve the seismic performance of the structure, thus minimizing the pushing effect of the infill wall on the main frame. Masonry infill walls with flexible connection have lower out-of-plane stability than walls with rigid connection. However, local collapses are more likely to occur. A comparative study was conducted on the load-carrying capacity, initial stiffness, deformation and ductility of different wall structures based on a monotonous static load test, and the out-of-plane mechanical properties exhibited by flexible masonry infill walls were investigated. A simplified separated finite element model of masonry infill wall was built in accordance with the test results, and then the monotone out-of-plane static loading was performed. The structural configuration, the wall-frame connection method, and the spacing between structural columns were found to have significant effects on the out-of-plane mechanical behavior of the infill wall. The wall structural configuration was found to have the strongest effect, followed by the wall-frame connection method. Under the conditions of flexible connection, when the wall structure was in the “grid-beam” form, and the spacing between structuring columns was 2.5–3.0 m, the frame-infill wall was found with the best restraint effect, so the optimal out-of-plane comprehensive mechanical performance would be achieved.

Distinct element modeling of the in-plane and out-of-plane response of ordinary and innovative masonry infill walls

Masonry infill walls (MIWs) are essential partition components that are often damaged during earthquakes because of their brittle nature. As a result, innovative solutions are attractive to improve performance of MIWs by reducing damage during in-plane drift or increasing damping. Examples of innovative solutions have been investigated experimentally, but mesoscale or microscale numerical modelling techniques could also be useful to evaluate performance and investigate the principal failure mechanisms of both ordinary and innovative MIWs, and subsequently optimize their design. This paper employs the Distinct Element Method (DEM) to predict the in-plane (IP) and out-of-plane (OOP) response of ordinary and innovative MIWs within RC frames. The DEM methodology used in this study account for the crushing of concrete and masonry, the shear-compression behavior of mortar and the shear behavior of a novel damping layer joint (DLJ) inserted in the MIW (named damped masonry infilled wall (DMIW)). DEM results are compared against experimental results for both MIWs and DMIWs. Two IP and four OOP experimental tests were simulated in total. The DEM simulation methodology is capable of predicting the IP and OOP load–displacement response as well as the damage patterns of the ordinary MIWs and DMIWs, although the local displacement mechanism at the DLJ locations of the DMIW varied for the OOP tests. Local stress distribution differences, as well as modeling modifications for simulating the damage pattern of DMIWs, are further discussed. Overall, the effectiveness of the DEM simulation provides confidence that it could be used to improve upon the DMIW design in the simulation environment.

Experimental behavior of masonry infilled RC frames with openings strengthened by using CFRP strip

This study examines the general load-displacement behavior of reinforced concrete frames with opening masonry infill walls in different sizes and locations under lateral earthquake loading. In addition, a strengthening detail was developed with anchored CFRP strips to reduce the negative effects of openings in masonry infill walls on the performance of reinforced concrete frames with infill walls. Experimentally, it was investigated to what extent the proposed strengthening method could improve reinforced concrete frames and masonry infill walls with openings. The variables examined in this study were determined as the size of the openings left in the masonry infill walls and their location in the frame. As a result of the tests of the first series of test specimens in the experimental program, the negative effects of the openings left in the masonry infill walls on the performance of the infilled wall frame systems under the effect of earthquake loading were determined. Within the scope of the study, the effectiveness of the strengthening method with the infilled test specimens was determined in the second series. Within the horizon of the study, the strengthening method developed with anchored Carbon-Fiber-Reinforced-Polymers (CFRP) strips increased the ultimate load capacity, initial stiffness, displacement ductility ratio, and energy dissipation capacity values of the masonry infilled frame systems with opening by an average of 72%, 11%, 13%, and 10%, respectively.

In-plane/out-of-plane seismic performance of masonry infilled RC frame structure made of nano-SiO2 reinforced mortar: Experimental study

Due to the seismic vulnerability of conventional masonry infill wall Reinforced Concrete (RC) frame buildings, which caused the infill wall structure to break and collapse, resulting in serious casualties and property damage. It was necessary to fully understand the action mechanism and seismic strengthening of the infill wall structure. Considering that few researches had paid attention to the effect of mortar performance on the seismic behaviors of infill wall structure, this study was the first to use a nano-SiO2 (NS) reinforced mortar to construct masonry infill wall RC frame structure. The pure out-of-plane (OOP) and in-plane and out-of-plane (IPOOP) loading tests were conducted to validate the structure's seismic performance. The experimental results of comparison with ordinary mortar specimen were shown. Due to the mitigation of the cracking of wall in pure OOP test, the initial stiffness, load-bearing capacity and ultimate displacement of new mortar specimen were increased by 65.88%, 23.57% and 11.12%, respectively. However, both infill wall specimens exhibited the similar cracking characteristics and load-displacement response, those indicated that the improvement in mortar performance was not sufficient to change the failure mode. In the in-plane (IP) tests, the infill walls constructed with new mortar provided a better diagonal bracing mechanism, resulting in a 13.32% and 12.67% increase in the IP load-bearing and energy dissipation capacity. The less side shear cracking of infill wall caused stiffness degrades more slowly. In the IPOOP tests, at approximately the same previous IP damage level, the slower propagation of crack resulted in a slower reduction in the load-bearing capacity and an increase in the deformability during subsequent OOP loading. Therefore, the application of the new mortar improved the shear and bond strength of the members, which mitigated IP damage and improved the stability of the wall, while slowed down the OOP cracking of the wall and reduced the risk of collapse.

Global response of reinforced concrete framed building under varying blast load pulse shapes

Reinforced concrete buildings subjected to explosive loading and their subsequent effects have become a subject of attention in the past few years due to extensive loss of life and severe structural damage. An explosion can occur with various random pressure–time histories known as pulse shapes and these pulse-loading shapes are expected to have significant influence on the dynamic response of structures. This study investigates the response and extent of damage in reinforced concrete framed building under varying blast load pulse shapes. The research involves three major objectives as quantification of blast load and formation of varying pulse shapes, numerical modelling of reinforced concrete building (bare and masonry infilled) with application of blast loads using finite element method and global response evaluation by nonlinear time history analysis. Generally, masonry infill walls are treated as non-structural elements and often ignored in structural analysis and design. This study includes investigating the effect of masonry infill only in the in-plane direction of blast loads with varying pulse shapes. Results show significant damage particularly on the front façade due to concave and half-cycle sine shaped blast pulse shapes. At the same time, the in-plane strength and stiffness of masonry infills have significantly reduced the overall damage in structural components.

Displacement incompatibility shape functions between masonry infill wall panels and reinforced concrete frames

During an earthquake, the detachment and local interaction between infill wall panels and surrounding frame can occur, potentially leading to significant local damage to both structural and non-structural elements, if not global collapse. Yet, a procedure to assess the relative deformation mechanism in terms of detachment shape and values, rather than, and in addition to, the diagonal compression strut mechanism and associated internal panel strain and stress path, is still missing in the literature. Therefore, in this paper the concept of shape functions is proposed and adopted to assess the seismic displacement incompatibility between infill walls and the surrounding frame structure. A parametric study on different typologies of infilled frames is developed to investigate the key parameters affecting the infill-frame detachment. The proposed concept of shape functions can support the design/retrofit of improved construction details, such as shear keys and/or steel dowels, in view of either decoupling or strengthening retrofit/repair strategies. Moreover, as infill-frame detachment can lead to damage to energy enhancement rehabilitation solutions, such as external thermal insulation systems, which are becoming more common nowadays in view of the international target towards a significant reduction of energy consumption and CO2 emission, it is suggested to implement the proposed displacement-compatible design check to assess and detail for adequate displacement capacity.

Numerical Simulation of the Blast Resistance of SPUA Retrofitted CMU Masonry Walls

Through numerical simulation, the blast-resistant performance of spray polyurea elastomer (SPUA) retrofitted concrete masonry unit (CMU) masonry infill walls under far-range blast loading was studied. From an engineering perspective, the effects of boundary conditions and thickness of a SPUA layer on enhancing the blast resistance of masonry infill walls are discussed, and the blast resistance of SPUA-retrofitted and grouted CMU masonry infill walls are compared. It is concluded that the boundary constraint conditions and the anchorage length of SPUA layer have limited improvement on the blast-resistant performance of the wall; the thickness of SPUA layer can significantly improve the blast-resistant performance of the wall as the blast loading increases. In addition, SPUA retrofitting shows relatively better performance to reinforce masonry infill walls.

Numerical Study on the Dynamic Behaviors of Masonry Wall under Far-Range Explosions

As a common enclosure structure, masonry walls are widely used in various types of buildings. However, due to the weak out-of-plane resistance of masonry walls and the generally brittle properties of the materials used for blocks, they are highly susceptible to collapse under blast loads and produce high-speed splash fragments, which seriously threatens the safety of personnel and equipment inside buildings. In this paper, based on the existing tests, a refined numerical simulation model was established to carry out numerical studies of clay tile walls and grouted CMU masonry infill walls under far-range blast loads, and the applicability of the finite element model and parameters were verified. Further, the effects of wall boundary configuration, constraints and dimensions on the dynamic response of the walls were carried out. The results show that: the load distribution on the wall is relatively uniform under the far-range explosion and can be considered as uniform load; the blast-resistant performance of the wall can be enhanced by increasing the grouting rate and the uniformity of grout hole distribution; the boundary configuration of the wall has little effect on the blast resistance, while the boundary constraints and the length and width are the main factors affecting the blast resistance of the wall.

Out-of-plane behaviors of unreinforced and spray polyurea retrofitted one-way masonry infilled walls

Unreinforced masonry infilled wall (MIW) is prone to out-of-plane (OOP) crack, bend, and collapse when subjected to OOP quasi-static and blast loadings. Spray polyurea (SPUA) is an excellent retrofitted material for MIW to improve its blast resistance and reduce fragmentation. Aiming to study the OOP behaviors of one-way unreinforced and SPUA retrofitted MIW under quasi-static and blast loadings, the corresponding OOP resistance functions of MIW under uniform loading are firstly established. The critical collapse deflection of unreinforced MIW is determined as δ = t-a, and the ultimate deflection of SPUA retrofitted MIW depends on the fracture strain of SPUA. Then, the quasi-static OOP uniform loading test on two full-scale one-way MIW was performed, and the OOP loading-deflection curves of MIW were obtained. It indicated that MIW is divided into two parts by the mid-height horizontal crack, and the upper and lower parts are rotated around the top and bottom mortar joints. Furthermore, by comparing with the present and existing quasi-static test data on unreinforced and SPUA retrofitted MIW, as well as the specified resistance functions by regulations (UFC 3-340-02, Eurocode 6, FEMA 306/356) and previous scholars, the applicability of established OOP resistance functions is validated. Finally, the equivalent single degree of freedom (SDOF) calculation approach to predict the dynamic responses of one-way unreinforced and SPUA retrofitted MIW under blast loadings is proposed based on the established resistance functions. The comparisons with five series blast tests demonstrate that the proposed SDOF approach can well predict the OOP deflection of MIW and evaluate whether the wall collapses or not. This work can provide a helpful reference for the blast-resistant evaluation and design of unreinforced and SPUA retrofitted MIW.

Quick Repair of Damaged Infill Walls with Externally Bonded FRPU Composites: Shake Table Tests

The paper presents the results of research on a nearly full-scale, 1-story reinforced-concrete (RC) spatial frame structure with masonry infill walls tested on a shake table. The experiment was conducted in four phases to investigate the in-plane and out-of-plane responses of the infill walls of the specimen. The use of a digital image correlation (DIC) technique with noncommercial analysis system allowed the computation of principal strains for the infill. Two methods of infill-RC frame protection using polyurethane resin (PU) flexible joints (PUFJ) at the RC frame-infill connection and an external innovative fiber-reinforced PU (FRPU) repair system were considered in the research. The test results indicated that the in-plane and out-of-plane infill performance was enhanced under seismic excitations. The PUFJs at the interface of the frame and infill walls helped the infills to withstand dynamic excitation of high intensity with repairable damage. Furthermore, the externally applied glass FRPU repair system efficiently protected the damaged masonry infills against collapse under out-of-plane excitation while restoring a significant portion of their in-plane stiffness. The variable contributions of the RC frame and of the brick infills when protected with innovative joints are evaluated through three-dimensional finite-element models.

Reliability Assessment of Masonry Infilled RC Frame Building’s Earthquake Performance through Accidental Torsion Consideration

Accidental torsional behaviour induced by horizontal loading is difficult to predict, being a complex phenomenon governed by many variables. This problem gains an additional dimension of complexity when nonlinear responses with imperfections need to be considered. Therefore, evaluation and understanding the influence of accidental torsion are fundamental in seismic reliability estimation. This study offers vital insights based on the results of a 1/2.5 scale three-story masonry infilled reinforced concrete frame building’s test on a shaking table. The building was tested under ten consecutive ground motions with increasing ag/g, recorded at Herzeg Novi station during the 1979-M6.9 Montenegro earthquake. The accidental eccentricity, considered a random variable, resulted from unsymmetrical masonry infill wall damage in an otherwise regular building. Its effect, in relation to that of other random (design) variables, was evaluated utilising weight factors and, in addition, assessed through various building code provisions and state-of-the-art research findings. The analysis revealed that the accidental eccentricity, as compared to other random variables considered, could, under certain conditions, reach values higher than those prescribed by the building codes. This unacceptable seismic reliability clearly warns that accidental torsion of masonry-infilled reinforced concrete frames in in-situ conditions must be considered even in regular buildings. Doi: 10.28991/CEJ-2023-09-02-017 Full Text: PDF

Seismic Behaviour of Building with Soft Storey: Review

Abstract: The high-rise building in which ground storey consists of open space is known as building with soft floor. Such floor plays an important role in seismic performance of the building. This is due to the abrupt changes in lateral stiffness and strength caused by such storey. In the present era there is increase in population, finding parking for flats in congested areas has become a significant issue. As a result, erecting multistory structures with an open first floor is now a widespread practice. These Buildings that have all upper storeys enclosed by masonry walls but no infill masonry walls in the ground story are referred to as "Soft Storey" or "Open Ground Storey Buildings." Compared to regular buildings, irregular structures the drift is observed to be effectively reduced by larger columns, while the shear force and bending moment on the first floor are increased. During a violent earthquake, the Soft Storey buildings function poorly. Understanding the behavior of is this study's primary goal to the building in a seismically active area and to assess the effects of Storey overturning moments, Storey drift, displacement, and design Base shear. For comparison, G-15 story building with five completely distinct shapes a square, an L-shaped building, a Tshaped building, a plus shape building and a C-shaped building is used. ETABS 2018 version is used to analyze the entire set of models. Dynamic Analysis has been examined in the current work to assess the deformation of all five-shape building with and without soft storey considering at different level. When the soft story is offered at a higher level, displacement is reduced. Several studies on this subject that have been done in the past are reviewed in this paper. Reviewing research papers let us know about the conclusive results, which served as the basis for the objective of our future study.

Effect of masonry infill walls on the nonlinear response of reinforced concrete structure: October 30, 2020 İzmir earthquake case

On October 30th, 2020, at 14:51, İzmir was hit by an Mw = 6.6 magnitude earthquake. The earthquake caused significant damage in Bayraklı, Karşıyaka, and Bornova districts. Structural damage and life losses were observed to be concentrated in Bayraklı region of İzmir. Twelve reinforced concrete buildings were collapsed in Bayraklı.Previous devastating earthquakes have shown that the damaged buildings are not very high-rise buildings, generally the lower storeys of which are car parks, and commercial enterprises, and there are no infill walls on the ground storeys. The same happened in the buildings destroyed in the October 30, 2020, İzmir earthquake.In this study, the effects of infill walls in reinforced concrete buildings under earthquake effects were investigated. For this purpose, a building damaged in the 2020 İzmir earthquake was examined. The building discussed in the study was modeled in the SAP2000 V22 finite element program in two different ways, with and without infill walls, using the real parameters of the building. As a result of the study, the results of the analysis were compared, and it was observed that the infill walls positively affected the features of the building, such as period, ground storey shear force, column bearing capacity, inter-story drift ratio, and base shear forces on the ground storeys, and increased the base shear force.

Effect of infill masonry wall with central opening on seismic behaviour of reinforced concrete structure

Effect of infill masonry wall with central opening on seismic behaviour of reinforced concrete structure

Effect of infill masonry wall with central opening on seismic behaviour of reinforced concrete structure

Effect of infill masonry wall with central opening on seismic behaviour of reinforced concrete structure

Application and Prospect of New Masonry Infilled Wall

As a new wall material, autoclaved aerated concrete (AAC) can realize the self-insulation system of "single material" wall in different climate regions in China. At the same time, it has obvious advantages in engineering construction, such as saving resources, easy processing, and good fire resistance. Therefore, AAC can be used as the preferred wall material for infilled walls of frame structures and load-bearing walls of residential multi-story buildings. In this paper, firstly, the main characteristics of AAC blocks are briefly explained. Then, the seismic performance of Reinforced Concrete frame of AAC, the impact of hole characteristics on its mechanical properties, and its compressive properties are analyzed and explored. It is expected that AAC blocks will be widely used and developed in the process of filling construction in the future.