Infill Walls Research Articles

Experimental study on progressive collapse of self-centering precast concrete frame with infill walls

The self-centering precast concrete (PC) frame has been proved to perform excellently under seismic load in many studies. However, its progressive collapse-resisting mechanism, especially in the presence of infill walls need to be investigated further. Three 1/2 scaled self-centering PC frame specimens, including one self-centering PC frame and two self-centering infilled PC frames were tested under quasi-static pushdown loading regime. The test results showed that the damage of self-centering bare frame was mainly concentrated at the beam ends under vertical load. The compressive arch action (CAA) and the tensile force in the prestressed strands undertook the vertical load together at the beginning of the test. The infill walls with lower strength could still obviously enhance the initial stiffness and progressive collapse resistance of self-centering frame, but did not change the failure location of the frame. The initial stiffness of self-centering infilled frame was 2.47 times of self-centering bare frame, and the peak load in the CAA stage was 1.33 times. The additional load path produced by the infill walls mitigated the concrete damage at the beam ends, thereby improving the ductility performance and repairability of the beams. As the beam span of self-centering infilled frame decreased by 1/4, the initial stiffness and peak load in the CAA stage increased by 1.65 times and 1.66 times respectively. Nevertheless, the concrete damage at the beam ends became severer and the ductility of the frame was reduced.

Numerical Modelling of Structural Behavior of RC Frames With and Without Infill Walls Subjected to Progressive Collapse

This paper aims to develop a numerical model of RC frame considering the same geometrical properties, material properties and boundary conditions in ABAQUS and validated with the experimental results comparing its force-displacement curve, damage pattern and stress and strain variations with the experimental outcomes. The use of infill walls increases the progressive collapse resistance force, mainly in the CAA. This is due to the addition of compressive action of infill walls to beam bending and CAA of RC frame. Plastic hinge was observed at the beam ends in case of RC bare frame. However, in the case of RC frame with infill wall, the plastic hinge was formed at some distance from middle joint interface and near the adjacent column joint on first floor and at some distance from adjacent column joint and near middle joint interface on second floor. Furthermore, in order to examine the effect of full height infill walls on progressive collapse resistance mechanism, RC frame with full height concrete block is modeled in ABAQUS and compare the results. It is seen that the RC frame with full height infill walls provides much higher progressive collapse resistance force in all stages i.e. beam mechanism stage, transient stage and catenary action stage.

Collapse performances of 3D post-tensioned RC frame structures considering combined influences of infill walls and floor slabs

This paper investigates the combined influences of infill walls and floor slabs on mechanical behaviors of post-tensioned (PT) reinforced concrete (RC) frame structures against collapse. Four PT frame structures modified from experimental specimens are studied. Applied loads, horizontal displacements, failure modes and resisting mechanisms are analyzed, and the roles that infill walls and floor slabs play are discussed. Parametric analyses are performed to study influences of opening in infill walls, diameter of wires in floor slabs and PT force in beams on collapse resisting capacity of PT frame structures. Results indicate that infill walls behave as equivalent compressive struts, increasing the horizontal deformation, changing the failure mode of PT frame structures; Floor slabs provide restraints on all columns and reducing the horizontal deformations of structures. Out-of-plane deformation develops in infill walls due to the two-way bending effect of floor slabs. The opening decreases the influence of infill walls, and the resisting capacity of PT frame structures enhances with increasing diameter of wires in floor slabs and PT forces in beams. A design method is developed to estimate collapse resistance of PT frame structures with good accuracy and efficiency.

Seismic behavior of hinged steel frames with masonry infill walls

Historic buildings are important parts of our cultural heritage and contribute to the social and economic of communities. Hinged steel frames with masonry infill walls were extensively used in conserved historical buildings built in the early 20th century in Shanghai, China. Those historical buildings are characterized by low strength in materials and the seismic actions were not properly considered in designs. Therefore, a better insight into their seismic performance assessment is necessary for both structural rehabilitation and maintenance of historic architectural features. This paper describes an experimental and numerical investigation on seismic behavior of hinged steel frames, with a special focus on the effect of masonry infill walls. Shaking table tests were conducted on two 1:4 scaled three-story, two-bay hinged steel frame model structures, i.e., a bare steel frame (Model M1) and a steel frame with masonry infill walls (Model M2). Three seismic records, i.e., Shanghai artificial signal (SHW-II, which was specified for the type IV soft base conditions in Shanghai), El Centro signal (obtained from the Imperial Valley earthquake in 1940) and Pasadena signal (obtained from the Kern County earthquake in 1952) were selected. The failure modes, dynamic characteristics, acceleration, inter-story shear forces as well as inter-story drifts of the two model structures were measured and compared. Three-dimensional finite element (FE) models of hinged steel frames with and without masonry infill walls were established. Effects of the stiffness of beam-column joints and the distribution of infill walls were also investigated. Results indicated that masonry infill walls altered the distribution of lateral force and increased the stiffness of the frame, leading to a noticeable reduction of structural deformation. The effect of infill walls was related to the ratio of stiffness of the walls to that of surrounding frames. In addition, a soft-story mechanism could occur in the case of partially infilled frames.

Experimental and numerical studies of improving cyclic behavior of infilled reinforced concrete frame by prefabricated wall panels with sliding joints

This paper aims to introduce a new type of damping infill wall system to alleviate the negative infill-frame interaction of fragile infill walls for reinforced concrete (RC) frames and improve the cyclic behaviors of the entire system. Three tested specimens including specimen BF (a bare RC frame), specimen CWF (an RC frame with ordinary infill walls), and specimen DWF (an RC frame with novel damping infill walls) are designed and fabricated. Quasi-static cyclic tests are conducted to them for exploring and comparing their cyclic behaviors. Experimental results reveal that severe destruction appears upon the conventional infill walls due to the negative infill-frame interaction. On the contrary, no significant cracks or damage are viewed in the new damping wall panels at the inter-story drift ratio of 4.00%. It confirms that the unfavorable infill-frame interaction under horizontal loadings can be mitigated by the developed damping infill systems effectively. The developed innovative infilled RC frame and the bare RC frame exhibit similar cyclic behaviors, including the hysteretic response, loading capacity deterioration, secant stiffness deterioration, and displacement ductility. Furthermore, by using the advanced infill wall system, the RC frame can dissipate energy more efficiently by over 15.71% and ameliorate the degradation of energy dissipation capacity through the stable damping force from the sliding joints. Additionally, numerical models and specimens show similar cyclic behaviors, which testifies to the validity of the pseudo-static experiment and numerical simulation. Parametric results reveal that the influence of developed wall panels made of different strengths of concrete for ameliorating seismic performance of infilled RC frames is very little, whereas the friction factor in the sliding joint is the essential element for enhancing the capacity of infilled RC frames to bear the lateral loadings.

Experimental analysis on the structural seismic behavior of steel frame-precast steel reinforced concrete (SRC) infill wall with lateral force resisting

The structural seismic performance of steel frame-precast steel reinforced concrete (SRC) infill wall with lateral force resisting is analyzed, and the structural strength of steel frame-precast SRC infill wall with lateral force resisting is improved. The structural seismic performance optimization model of SRC lateral force resisting wall based on buckling restrained brace is proposed. Through the finite element simulation software, the seismic performance and response results of ordinary steel frames, buckling restrained braced steel frames and a relatively new type of sacrificial-energy dissipation braced steel frames under earthquake are compared and analyzed to demonstrate the applicability and performance advantages of sacrificial-energy dissipation braced steel frames in the steel frame braced structure system. Under the action of horizontal earthquake, the supporting members experience reciprocating axial tension and compression cycles, which dissipate a large amount of seismic energy input into the structure. Therefore, the buckling restraint support method can be used in the structure to improve the support strength. Under horizontal reciprocating load action of earthquake, the ability to consume seismic energy through self-hysteresis of the brace is poor. Experimental research shows that, the unbalanced force formed in the beam of the frame beam under seismic action will form a plastic hinge at the beam end at both ends of the frame beam. Especially when the brace is buckling unstable and the stiffness of the frame beam is small, the plastic hinge effect at the beam end is significant. This phenomenon may cause damage to the frame beam or even local floor subsidence. The buckling restraint support has a full hysteresis area under axial tension and compression, and its mechanical performance is excellent. It is obviously superior to ordinary steel bracing in energy dissipation capacity and seismic performance. It can accurately predict the bearing capacity of reinforced concrete under strong earthquake, and the energy dissipation distribution is more in line with the requirements of “energy seismic design method”.

Experimental study on seismic performance of modular cast-in-situ coupled shear wall with LRC infill wall

Experimental study on seismic performance of modular cast-in-situ coupled shear wall with LRC infill wall

Experimental and numerical investigation on progressive collapse of self-centering precast concrete frame with infill walls

Two 1/2 scaled self-centering precast concrete (PC) frames with and without infill walls were experimentally and numerically investigated under quasi-static pushdown loading regime. The test results showed that the main failure modes of self-centering PC frames were concrete cracking and spalling at the beam ends. Compared with self-centering bare frame, since the infill walls undertook partial vertical loads, the concrete damage at the beam ends of self-centering infilled frame was reduced. Since the lower strength of AAC blocks and mortar, the presence of infill walls did not change the failure mode and failure location of self-centering PC frame. The infill walls with lower strength could still significantly enhance the initial stiffness and collapse resistance of the structure. However, infill walls also reduced the self-centering capacity of the structure. The simulation results indicated that the prestress force of steel strands between beams and columns had a greater effect on the structural resistance of self-centering PC frames. For the self-centering infilled frames, the progressive collapse-resisting capacity of infill walls mainly depended on the strength of bed joints, while the effect of the cross joints was negligible. When the mortar joints had a lower strength, the increase in block strength had limited effect on the increase in structural resistance. With the increase of strength of mortar joints, the effect of variation of block strength on the structural resistance became obvious. Finally, the proposed analytical method had a relatively better accuracy to predict the vertical resistance of self-centering PC frames.

Effect of Infilled Walls On The Performance of Steel Frame Structures

Today, the subjectof a building's resistance to lateral loads is one of the most important concerns of structural engineers. The partitions and infilled walls are non-structural elements that are important due to their effects on the lateral resistance of the building frame. Recently, it has been observed that great damage is occurring to infilled walls, partitions, and buildings in an earthquake-prone area. Infilled walls are effective at increasing the hardness and resistance of building frames, which changes the seismic properties of structures. Therefore, the study of interactions between the structural frame and the infilled walls is essential for a better understanding of structural behaviors. In this paper, the effect of infilled walls is investigated on the behaviour of steel frames using ABAQUS software. Modeling is carried out for different types of infilled materials, including brick and panel, as well as different thicknesses of the infills. It was observed that with an increase in the thickness of infills from 7 to 20 cm, the final capacity and energy absorption increased by 78%. Also, the panel-infilled frames have 18% more capacity and 3.8% more energy absorption than the brick-infilled frame in the same full state. As a result, panel-infilled frames outperform brick infilled frames in terms of performance.

Effectiveness of structural walls in improving the serviceability of a seismically-retrofitted RC building

AbstractA moderate earthquake with a magnitude Mw of 6.8 hit the Elazig Province of Turkey on January 24th, 2020, causing fatalities and structural damage/failure. Following the earthquake, a field reconnaissance was conducted at the Administration and Operation Campus of Karakaya Dam, which is 19 km from the earthquake epicenter. The exhibited performances in two side-by-side nominally identical reinforced concrete (RC) buildings with the same material properties and soil conditions differed significantly. The main reason lies in the preventive action taken before the earthquake in one of the buildings. The building retrofitted with additional structural walls had a slight/no damage level. However, the non-retrofitted building suffered severe damage due to large cracks in numerous infill walls, some of which were exposed to partial collapse. That makes the non-retrofitted building unserviceable, requiring evacuation after the earthquake. The field-observed building damage was compared with the seismic performances acquired from their refined numerical models for the recorded ground motions. The photographic documentation exposing the entire performance and damage level in non-retrofitted and retrofitted buildings was quantified by static pushover and nonlinear response history analyses. The post-earthquake performance of nonstructural members in retrofitted and non-retrofitted buildings was simulated with reasonable accuracy.

Seismic response of multi-storied building with shear wall considering soil-structure interaction in Patna, India

The structural response of a building on soft or loose soil differs from that on hard and rocky soil. Investigating the behaviour of buildings with shear walls on such soft soil is essential. This study considers four structural models of the nine-storied building with and without infill walls. The modelled buildings represent the existing buildings in the Patna, India region. The frame was analysed in four different conditions: (1) Fixed base bare frame building, (2) Flexible base bare frame building, (3) Fixed base building with shear walls (4) Flexible base building with shear walls. Twenty-four pairs of scaled ground motion from the PEER Ground Motion Database were selected, and a nonlinear time history analysis was performed in SAP2000v20.0. Understanding that soil-structure interaction is paramount for building on soft soil, the study quantified the seismic response for the building in the Patna region, a region of high seismicity.Moreover, in current scenarios, multistorey buildings with an open ground storey and shear walls are prevalently found owing to their advantage for parking and enhancing the seismic capacity. The result shows that base flexibility significantly increases the peak floor displacement, total floor acceleration, inter-storey drift and displacement ductility for bare frame structures. At the same time, consideration of shear and infill walls only affects the flexible base structures. While shear and infill walls significantly affect the seismic behaviour of the fixed base structure. It was also found that the shear and infill walls increase the structure’s stiffness and thus reduce the fundamental vibration period of the structure. The study’s significant findings are (1) the shear and infill wall significantly reduces the seismic responses of the building, (2) base flexibility (SSI) increases the seismic vulnerability of the buildings, (3) the displacement ductility significantly depends on the aspect ratio (height/width) of the building, and (4) the inter-storey drift is relatively higher in the lower and mid storey of buildings.

Experimental investigation on the in-plane and out-of-plane interaction of isolated infills in RC frames

This paper presents the findings of a series of bidirectional quasi-static tests conducted on isolated infilled frames to investigate the in-plane and out-of-plane interaction of the infills with different boundary constraints. The effects of prior in-plane damage on the out-of-plane behavior of isolated infill walls were assessed. It was found that the presence of existing cracks that developed during the in-plane loading stage had an effect on the out-of-plane cracking patterns, decreased the integrity of the isolated infills, and weakened the infill-frame boundary restraints. The behavior of isolated infill walls under combined in-plane and out-of-plane loading was also affected by the effectiveness of boundary constraints. The experimental results demonstrated that reliable boundary constraints were necessary for forming arching mechanisms and preventing rigid body motion.

Monotonic and cyclic sway behaviour of 2-dimensional frames made of pultruded GFRP I-section profiles

This paper presents an experimental study on the structural response of 2-dimensional full-scale frames comprising pultruded GFRP I-section profiles under lateral quasi-static monotonic and cyclic loading, including four different frame configurations, to assess (i) the influence of using different beam-to-column connection systems (one series included cleats and other included cuff parts); (ii) the benefits of using bracings (one series included a cable bracing system); and (iii) the impact of using infill walls (one series included plasterboard panels). The beam-to-column connections and the bracing system were materialized exclusively with stainless steel parts. The results of the monotonic tests showed that the type of beam-to-column connection has considerable influence on the frames’ response, namely on their lateral stiffness; additionally, the frame with bracings and the frame with infill walls exhibited the highest strength and stiffness, respectively, among all series. In the cyclic tests, all frames presented considerable pinching, limiting the energy dissipation; the results showed that the benefits of the infill walls should not be accounted for in design and that the bracing system used is not adequate for seismic areas, as both the plasterboards and the cable bracing system presented non-recoverable deformations/damage that limited their structural contribution from that point forward. The best performing frame series without bracings or walls was simulated using a simple finite element (FE) model. The profiles were modelled using frame elements and the beam-to-column connections were simulated using link elements with the Pivot hysteresis model, calibrated from previous experiments on the beam-to-column connection system. The FE model was able to predict the lateral response with reasonable accuracy, validating this numerical procedure. Then, the FE models were used to evaluate the effects, on the cyclic performance, of including GFRP bracings and a steel plate damper, leading to an improved hysteric response, especially in what concerns the energy dissipation capacity. Overall, the results show that (i) even with ductile connections, the energy dissipation capacity of simple pultruded frames is limited, (ii) although they present high drift capacity; (iii) simple models can be used for design purposes and (iv) they show that the introduction of material-adapted dissipation systems can improve the seismic performance of pultruded frame structures.

A novel holistic approach for the seismic-energy performance assessment of masonry infill walls

The masonry infill walls are often used in the envelopes of reinforced concrete buildings for different purposes, but a large part of them was built before the enforcement of modern seismic and/or energy codes. Due to that, the envelope of the reinforced concrete buildings is responsible for the energy consumption needed for indoor heating and cooling. At the same time, recent earthquakes proved that the infill walls located at the envelope are quite vulnerable under OOP seismic loadings resulting in extensive damage or collapse. The existing standards only provide slight provisions for designing new infill walls and do not combine their energy and seismic performance. Based on that, this research work aims to present a novel holistic performance assessment approach for masonry infill walls. This novel approach aims to classify each wall according to its seismic plus energy performance, allowing to identify which type of retrofitting is needed. A global overview of the international standards concerning the seismic design and assessment of masonry infill walls is performed. Also, the maximum and recommended U-values for external walls indicated by the national code of each European Union country are compared. After that, the new performance assessment methodology is presented and discussed. Finally, a pilot application is performed by carrying out the performance assessment of the infill walls of three buildings (with different numbers of storeys) located in different seismic-climate zones in Portugal. Several types of walls are studied according to their retrofitting type, i.e. non-retrofitted or with independent energy or seismic retrofitting or with combined seismic plus energy retrofitting. It was found that this performance assessment methodology provides important information to support future wall retrofitting. Combined seismic plus energy retrofitting is often needed in the different seismic-climate zones of the Portuguese territory.

Assessment of the effects of infill walls’ layout in plan and/or elevation on the seismic performance of 3D reinforced concrete structures

Assessment of the effects of infill walls’ layout in plan and/or elevation on the seismic performance of 3D reinforced concrete structures

Yüksek Dayanımlı Hafif Beton Paneller Kullanılarak Dolgulu Betonarme Çerçevelerin Güçlendirilmesi

This study proposed a practical seismic retrofit method for RC frames. For this purpose, a quasi-static loading was applied to 8 RC frames in finite element analysis software, Abaqus, and frames were pushed 45 mm laterally. High-strength fiber-reinforced lightweight concrete panels strengthened infill walls inside the RC frames. To apply them to the walls, epoxy binder and polyurethane binder were used, and their behavior was compared. Using panels increased the lateral load capacity of the whole frame according to the numerical analysis performed with Abaqus. In the worst case, the retrofitted frame carried approximately two times the traditionally infilled frame's capacity. In the best case, the RC frame carried 4.29 times the lateral load traditionally infilled frame. Polyurethane binder prevented the separation of panels from walls and provided a ductile behavior to frames even in large drifts.

Masonry Infill Walls Enhanced with the Reinforced Shotcrete in Blast Incidents

Masonry Infill Walls Enhanced with the Reinforced Shotcrete in Blast Incidents

To Evaluate Seismic Performnce of RCC Building With Floating Column with and without Infill Wall

To Evaluate Seismic Performnce of RCC Building With Floating Column with and without Infill Wall

Assessing performance of alkali-activated bricks incorporated with processed surgical masks

Since last few years the world is facing tremendous surge in the use of surgical masks due to the COVID19 pandemic. The uncontrolled disposal of surgical masks in the environment will pose serious threat to the living organisms due to plastic pollution. On the other hand, the construction industry is hugely dependent on natural resources, leading to increase in carbon footprint. Therefore, it necessary to investigate novel construction materials with sustainability perspective. In present study, alkali-activated bricks were synthesized with rice husk ash (RHA), ground granulated blast furnace slag (GGBFS), sand, and sodium silicate (SS). To this, processed surgical masks (PSM) were added in varying doses of 0%, 1%, 2%, 3%, and 4% by volume of the mix. The results revealed that addition of PSM significantly improved the strength properties of the bricks with a maximum compressive strength of 6.85 MPa at inclusion of 4% PSM. At the same time, it has reduced the density of bricks with a minimum value of 1.54 g/cm3 at inclusion of 4% PSM. The incorporation of PSM has slightly increased the water absorption and porosity of the bricks, with a maximum increase of 4.76% and 7.75% for bricks with 4% PSM, when compared to bricks with 0% PSM, respectively. The accelerated ageing test showed that after three cycles of wetting and drying the bricks exhibited loss in compressive strength in the range of 55.2%–58.6%. The microstructure results revealed the bridging effect of fibrous mask particles in improving the load transfer in polymer matrix, and thereby reducing the brittle tensile failure in bricks. The pushover analysis showed the benefit of PSM in improving the performance of the infill walls due to improvement in brick strength and reduction in its self-weight, and therefore, it can be considered as a potential material for use in construction of buildings in seismically vulnerable areas.

Structural behavior of steel tie connections in masonry veneer walls: Proposal of a simplified approach for practice

Steel ties perform a key structural role in ensuring the stability of buildings façades built with brick masonry veneer walls. These elements are responsible for transferring the loads acting on the veneer wall to the main structure, which typically consists of masonry infill walls used in reinforced concrete frames buildings. Such constructive system is common in Portugal and other Mediterranean countries where the seismic hazard is high. In the event of an earthquake, the ties have to transfer the out-of-plane loads and are subjected to significant tension and compression stress. The characterization of the seismic behavior of these tie connections is an insufficiently explored topic. Despite the codes available for the design of brick masonry veneers and ties, recent earthquakes brought to light the seismic vulnerability of this constructive system. The present paper proposes a simplified spring numerical model validated with experimental results. The simplified model can be applied to perform numerical analyses of greater scale (e.g. to analyze full façades of buildings), which can help to optimize the design. Finally, the paper identifies a common construction problem, which is the probable misalignment of the mortar joints of the masonry walls. A construction solution is proposed by the authors.