Infill Walls Research Articles

Strength assessment of structural masonry walls: analysis based on machine learning approaches

ABSTRACT In conventional masonry buildings, masonry walls are key structural load-bearing elements. Likewise, masonry infill walls strengthen framed constructions against lateral stress. The material characteristics of brick units and mortar determine the compressive strength of structural masonry walls. In this study, advanced machine learning (ML) techniques were utilized to estimate the compressive strength of structural masonry walls based on the material properties of brick units and mortar. The Young’s modulus of brick units (Eu), compressive strength of brick units (Fcu), Young’s modulus of mortar (Em), and compressive strength of mortar (Fcm) were used as input parameters to model the compressive strength (Fc) of the structural masonry wall. Gradient Tree Boosting (GTB), Elman Neural Network (ENN), and Multivariate Adaptive Regression Splines (MARS) were developed using four diverse input and output (I/O) combinations to explore the effect of each input parameter on output estimation. The data used for modeling were obtained from prior studies published in the literature. The model’s performance was evaluated based on different statistical (error and efficiency) indices. For the third and fourth (I/O) combinations, the MARS model significantly outperformed other models. However, for the first I/O combination, the GTB model performed well. The study also revealed that the compressive strength of a structural masonry wall is more likely to depend on the strength and quality of the brick units than on the strength of the mortar.

A novel Ductile Lightweight Fiber-Reinforced Concrete (DLFC) infill for seismic-prone zones: Experimental and numerical investigations

In urban construction, reinforced concrete (RC) with masonry infill predominates, though traditional masonry's brittle nature poses significant seismic vulnerabilities. This study introduces a novel approach using Ductile Lightweight Fiber-Reinforced Concrete (DLFC) as an infill to address these challenges. Composed of cement, water, expanded polystyrene (EPS), ultra-fine filler, and combined polyvinyl alcohol (PVA) and polypropylene (PPF) fibers, DLFC aims to enhance ductility, minimize damage, and amplify energy absorption in seismic events. Three RC frames, with height-to-span ratios of 0.77, 1.00, and 1.28, were designed and experimentally tested under simultaneous vertical and lateral cyclic loading to evaluate DLFC's seismic response. Results illustrated that DLFC-infilled RC frames boast impressive ductility, an 8% drift at complete failure, minimal out-of-plane behavior, and elevated damping ratios. Remarkably, DLFC's low in-plane stiffness led to reduced frame stiffness compared to traditional masonry. An empirical equation, closely aligning with experimental outcomes, was formulated to estimate the lateral strength of the infill wall, and a comparison with the bare frame was made, though it necessitates additional validation through further testing.

Numerical and Experimental Investigation on Cyclic Behavior of Masonry Infill Walls Retrofitted with CFRP

Numerical and Experimental Investigation on Cyclic Behavior of Masonry Infill Walls Retrofitted with CFRP

Out-of-plane behavior of masonry infilled Chuan-dou timber frames

The masonry infilled Chuan-dou timber frame is a traditional structural system widely used for non-engineered residential buildings in southwestern areas of China, where earthquakes are common. And the masonry is prone to out of plane (OOP) collapse due to the lack of an effective connection between the timber frame and the masonry. This paper discusses the OOP seismic performance of masonry infilled wall Chuan-dou timber frame. Considering the slenderness ratio and the compressive strength of mortar, three full-scale single-story specimens were subjected to airbag loading to investigate the out-of-plane seismic behavior of the structural systems. Two typical failure modes of the structural systems including one-way bending and shearing slip were observed in the study. The results indicated that the slenderness ratio of the infilled masonry was inversely proportional to the bearing capacity of the structural systems. The columns have a limited effect on the constraint of infill wall while the beam can prevent the wall from falling out of the frames. And the OOP seismic behavior of the infill wall can be improved by strengthening the connection between the infilled wall and the frame. At the same time, the formulas for peak OOP load are presented based on a two-hinged arching/rocking pier mechanism.

Effect of infill walls on seismic performance of multi-story buildings with shear walls

Effect of infill walls on seismic performance of multi-story buildings with shear walls

Experimental and numerical investigation of hysteretic earthquake behavior of masonry infilled RC frames with opening strengthened by adding rebar-reinforced stucco

Adding a reinforced stucco layer to the masonry infill walls is a preferred method for strengthening RC frame system structures with an easy-to-apply method that does not require a long time, is economical, and does not require detailed and extensive workmanship. However, no research has been discovered as a result of the extensive literature review that investigates the effects of masonry-infilled RC frames strengthened with a reinforced stucco layer on the seismic performance of openings that must be due to architectural requirements such as doors, windows, installations, and similar ventilation systems. As a result, an experimental study was planned to investigate the effects of the dimensions and location of the opening in the masonry infill walls on the performance of the strengthening method with the reinforced stucco layer. The applied strengthening method increased the ultimate load capacity, initial stiffness, and energy dissipation capacity values of reinforced concrete frames with masonry infill walls by 83%, 226%, and 62%, respectively, but resulted in a 38% decrease in displacement-ductility ratios. The study found that the openings in the masonry infill walls harm the performance of the strengthening technique by adding a rebar-reinforced stucco layer and decreasing the success level. When the opening size increased, and the opening was located at the corner of the masonry wall, the performance of the applied strengthening technique was negatively affected and decreased. Furthermore, nonlinear numerical analyses of the experiments conducted as part of the study were performed using ABAQUS finite element software. The numerical analysis results were compared to the experimental results. It has been determined whether numerical analysis models are compatible with experimental results.

Monitoring the changes in the dynamic properties of an RC building experiencing column loss

In this study, an existing six-storey reinforced concrete building with an asymmetric structural plan and soft storey irregularity was used as a test specimen and subjected to three-step progressive structural damages to detect the variations in its dynamic properties. Mode shapes and dominant frequencies of the undamaged building were determined by the ambient vibration survey (AVS) and it was seen that its first three modes were torsion coupled. Besides, soft storey irregularity was evident due to the lack of masonry infill walls on its ground floor. Later on, three-step progressive damages were applied to the building. The first step targeted three columns and one beam of the building, located on a corner region of its ground floor to peel off their clear covers. The second step razed two adjacent corner columns which were already moderately damaged in the first step, while the third step knocked the third moderately damaged column down. After each damage step, AVS was repeated with the same details as applied for the undamaged building. The obtained dynamic properties for the four phases of the building were evaluated with the sustained damage. Numerical analyses with the finite element model of the building representing its four different phases were also performed and the unique responses due to damage effects on the structure were investigated numerically. As a result of induced damage, the quantified amount of frequency change in modes and the new mode observed after particularly column loss scenarios can be utilized for efficient structural health-monitoring strategies of plan-asymmetric buildings and post-earthquake assessment of partially damaged buildings where timely objective assessment is important.

Seismic performance of light wood shear wall infilled timber frame structures with openings

To study the seismic performance of wood frame structures filled with light wood shear walls, three full-size single-layer single span wooden frame structures with infill walls were designed and manufactured. The beams and columns were connected by mortise-tenon joints, and quasi-static tests were conducted on the specimens under reversed cyclic load. The failure modes and load-displacement hysteresis performance of structures with door opening infill wall, window opening infill wall, and solid infill wall were investigated. The seismic performance was analyzed using indicators such as strength, ductility, and equivalent viscous damping ratio. The failure modes of light wood frame filling walls were the tearing of sheathing panel and the failure of nail connections. The filled wall with the opening initially exhibited inclined cracks at the corner of the opening, and then they extended to the periphery. Compared with the solid filled wall, the positive and negative bearing capacity of the structure with door opening decreased, and that of the structure with window opening decreased also. Because the specimens with opening in the filled wall were more conducive to the deformation of the structure when the bearing capacity was not significantly reduced, the ductility of the specimen with door opening was the highest.

Seismic Vulnerability of Bijapur’s Historic Architecture

Bijapur (Karnataka, India) in recent times, has been experiencing earthquake tremors frequently. The city and its environs are home to numerous historic buildings which are considered significant in the history of architectural development in the Indian subcontinent. The primary and most visual contribution to the city’s architecture happened in the 16th – 17th century CE under the Adil Shahi Sultanate. This present study focuses on the buildings of that period only. The buildings are more than 300 years old now and have decayed substantially with time. Recent earthquakes in Bijapur pose a serious threat to these structures and this study tries to assess the seismic vulnerability of the same. From the assessment, it is inferred that the sturdy design of arcuated buildings of Bijapur, arch-frame masonry structures without infill walls, slender building elements like tall minarets, and cantilevered elements like cornices collectively make the historic buildings of Bijapur vulnerable to seismic loads. Lack of maintenance, lack of conservation and consolidation initiatives, vandalism, and unplanned development in close vicinity of these edifices also contribute to the same. The method of assessment employed in this study is based on site surveys, physical documentation, condition assessment, and conceptual and non-conceptual literature available on the subject, instead of computation-based techniques of assessment for those methods have their limitation as far as (historic) masonry buildings are concerned.

Seismic assessment of the in‐plane/out‐of‐plane interaction of masonry infills in a two‐storey RC building subjected to bi‐directional shaking table tests

AbstractThis paper presents a series of shaking table tests conducted on a 60%‐scaled two‐storey infilled reinforced concrete building. The main parameters include the presence of openings in the masonry infills and the effect of bi‐directional dynamic shaking to the latter. The building was subjected to four different levels of shaking intensity, ranging up to the Maximum Considered Earthquake (MCE), equivalent to 150% of the design earthquake. The study focuses on and evaluates the damage caused by combined in‐ and out‐of‐plane shaking. Under the design level earthquake, the second‐storey infill walls with openings were severely damaged, with near‐collapse of a masonry pier. For the fully infilled direction without openings instead, diagonal cracking as well as out‐of‐plane inclination of the infill wall in the second storey were observed. Due to the interaction between the two loading directions and the direct adverse effect of the in‐plane damage on the out‐of‐plane resistance of the infills, the out‐of‐plane collapse of 3/4 of the second storey masonry infill occurred during the MCE. The reported damage observations on the masonry‐infills with or without openings provide further insights on the vulnerability of non‐seismically designed reinforced concrete buildings. Additionally, the seismic performance of the structure is assessed using further structural response quantities recorded during testing, including floor accelerations, inter‐storey drifts, base shear forces and reductions in natural frequency. Future testing will focus on investigating the effectiveness of retrofitting measures in improving the connection between the infill and frame, reducing in‐plane damage, and preventing out‐of‐plane failure of the infills.

Experimental Analysis of Out-of-plane Behavior of Masonry Infill Walls Strengthened with Textile Reinforced Mortar and Wall Post in Autoclaved Aerated Concrete Frames

An experimental study was carried out to contribute to the rather limited data on the out-of-plane (OOP) behavior of masonry infills in reinforced concrete (RC) frames strengthened with the wall post and the textile-reinforced mortar (TRM). For this purpose, one unreinforced specimen served as the control, one specimen was reinforced with the wall post, and two specimens were reinforced with the TRM. They were fabricated and subjected to cyclic OOP loading until a drift ratio of 6%. Load and displacement values were recorded, and the research team discussed the failure mechanisms of the specimens. Results showed that the application of the wall post had the highest efficiency as it increased the load by about 3 times, while this value for TRM-strengthened walls was only 1.5. Strengthening modified the cracking, shifting it towards the middle parts of the wall, changing it from a brittle to a failure mode. Comparison of the envelope curves of specimens revealed significant improvements. The ultimate displacement and energy absorption capacity for the specimen reinforced with the post wall increased by 30% and 300% respectively. Similarly, for TRM-strengthened specimens, these values were 48% and 100%.

Studying Several Parameters on Unreinforced Masonry Infill Walls R C Framed Structure by Seismostruct Program

Studying Several Parameters on Unreinforced Masonry Infill Walls R C Framed Structure by Seismostruct Program

Experimental and analytical studies of infill wall with sliding joints considering a door opening

AbstractSemi‐rigid steel frame stands out due to its remarkable deformation capability under seismic loading, while the introduction of partitioned walls would disturb the expected seismic behavior of the infilled steel frames. Furthermore, the presence of door openings might exacerbate these negative effects. To mitigate the detrimental multiple‐diagonal strut effect of traditional infill walls around the door opening, an innovative low‐damage wall panels system: prefabricated infill wall panels with a door opening and sliding joints are presented for semi‐rigid steel frames. For testifying the effectiveness of the proposed structure, a quasi‐static test was carried out on three half‐scaled steel frames: a bare frame, a frame infilled with conventional wall panels with a door opening, and a frame infilled with the novel wall panel system with a door opening. Experimental results reveal that the developed innovative wall panels with a door opening could avoid unfavorable crack developments and opening deformation around the door area. It is mainly attributed to the releasement of the adverse multiple‐diagonal strut mechanism of traditional wall panels with door openings. Thus, the presented infilled frame showcases seismic performance similar to the bare steel frame, while having a higher energy dissipation capacity. Moreover, the developed analytical prediction method based on the superposition principle could accurately estimate the lateral load‐carrying capacity of the structures. Due to negligible deformation of the both bottom infill wall panel and the door opening, the innovative infill wall only contributes about 10% lateral load‐carrying capability to the infilled frame.

Time-History Analyses on the Effect of Partial Infill Walls on the Seismic Response of a Reinforced Concrete Frame Structure

Time-history analysis (THA) is based on direct step-by-step integration of the equation of motion in time domain considering as input either the recorded accelerograms of real or artificially generated earthquakes. Numerical simulations are sensitive in terms of material properties, geometry, boundary conditions and applied loading scenarios correct definition. Therefore, additional care is required in the pre-processing stage of the analysis when the numerical model is defined. Infill walls play an important role on the seismic behaviour of structures during earthquakes. The response of the structure to seismic action changes due to the presence of the infill walls. The paper presents the results obtained by means of THA on the effect of partial infill walls on the seismic response of a scaled-down RC frame structure subjected to four consecutive uniaxial seismic motions. The parameters of the research were the presence of the partial infill wall and the thickness of the wall. The obtained results are discussed from the point of view of maximum lateral displacements and response spectra expressed in terms of accelerations. The results contribute towards the setting up of the subsequent shake table tests of scaled-down RC frame models with different configurations that would validate and help calibrate the numerical model.

Dynamic and uncertainty-based assessment of the progressive collapse probability of prestressed concrete frame structures with infill walls

Since progressive collapse usually has serious consequences, the problem of progressive collapse resistance has gradually become a topical issue in recent years. However, most of the existing studies have been conducted on common reinforced concrete (RC) structures. The methodologies used in the studies are also mostly static and deterministic. There is a lack of research that considers the dynamic effects and uncertainties of pre-stressed structures with infill walls. In this paper, the assessment of progressive collapse probability considering dynamic effect and uncertainties is performed for prestressed concrete frame with infill walls (IW-PC frame) structures. The finite element software OpenSEES is chosen as the analysis platform. By introducing uncertainties in material, geometry and load, five limit states and their quantitative indicators are identified. Based on the nonlinear incremental dynamic analysis (IDA) method, the vulnerability analysis of the IW-PC frame is performed under different working conditions. The vulnerability analysis indicates that the five levels of limit states can visually evaluate the degree of structural damage. Additionally, the resistance relationships of the four structural forms are as follows: IW-PC frame > reinforced concrete frame with infill walls (IW-RC frame) > prestressed concrete frame (PC frame) > RC frame. The load carrying capacity of the frames is significantly increased by the coupling effect of the infill walls and the prestressed strands. Moreover, the prestressed strands can reduce the probability of light and moderate damage, while infill walls have an excellent preventive effect on severe damage. The reliability of the four structures is evaluated using the Zhao-Ono moment method. The results indicate that IW-PC is the safest, followed by IW-RC, PC, and RC.

An Innovative Fire-Resistant Lightweight Concrete Infill Wall Reinforced with Waste Glass

In this paper, an innovative infill wall is proposed and examined experimentally and parametrically. The proposed wall has an innovative design and is constructed with lightweight concrete strengthened by waste glass. The proposed wall not only demonstrates robust performance against out-of-plane loading, but also exhibits exceptional behavior under elevated temperatures. Additionally, the necessary equations used to predict the wall’s behavior are also presented. The results reveal that glass powders affect weight loss. During the initial temperature application, ranging up to 600 °C, specimens with 0% and 8% glass powder experienced maximum and minimum weight loss, respectively. At 200 °C, glass powder concentrations below 4% caused a reduction in compressive strength, fc′, while concentrations between 4% and 8% led to an increase in fc′. Consequently, the optimal glass powder volume was determined to be 6% for specimens under varying temperature conditions. The out-of-plane loading tests indicated that although the wall was exposed to heat up to 800 °C, the resistance did not decrease significantly. Given its role as a non-load-bearing wall without the application of gravity, this innovative structure is anticipated to perform admirably in fire scenarios during seismic events.

Wall-frame interactive behavior in GFRP-reinforced steel plate shear walls with circular cutout openings

The present study investigates the effect of glass fiber reinforced polymers (GFRPs) on the nonlinear and energy dissipation behavior characteristics of steel plate shear walls (SPSWs) with a single circular cutout opening using the finite element method. In the study, the effect of the opening features (diameter and location), geometrical properties of the SPSW systems (aspect ratio and height) and properties of fiber laminates (number of layers and orientation angle) on the FRP-wall-frame interactive behavior is investigated. The results show that the introduction of opening does affect the distribution of stresses across the wall. The use of an adequate amount of FRPs can successfully compensate the impact of the opening on the system strength and energy dissipation capacity. The use of fibers does not change the system initial stiffness significantly, while it reduces the ductility to some extent. There is an interaction effect between FRPs, infill wall and frame, and the use of FRPs results in a better distribution of stresses across the perforated wall area at the ultimate state, although it causes a delay in the onset of wall yielding. The presence of opening in the infill wall of different SPSWs, especially in taller multi-story cases, improves the system ductility. Finally, a procedure is presented for design of FRP-reinforced perforated SPSWs and the accuracy of the proposed equations is compared with the finite element results.

Estimation of fundamental period of concrete frames with infill walls using decision tree

Estimation of fundamental period of concrete frames with infill walls using decision tree

Seismic strengthening of deficient ground soft-story RC frames with inadequate lap splice using chevron brace

Deficient RC frames with ground soft-story irregularity have been constructed in many countries. Past earthquakes have shown that such structures are vulnerable and must be retrofitted. This study investigated the cyclic response of two one-bay, two-story, 1/2.5-scaled RC frames with inadequate lap splice length through experimental works and numerical simulations. One of the frames was kept as the reference, and the other was strengthened using a chevron brace system. The frames were subjected to displacement-controlled quasi-static cyclic loading, and their cyclic responses were recorded and compared. Besides, the lumped plasticity model was used to investigate the effect of the strength of infill walls on the force-displacement response of the retrofitted frame. The experimentally obtained results indicated that the employed chevron brace system significantly enhanced the cyclic response of the reference frame. The retrofitted frame exhibited a 171% greater ultimate strength than the reference frame. Besides, the retrofitted frame's initial and post-yield stiffness were 2.2 and 6.9 times greater than that of the reference frame. At a 3.5% drift ratio, the retrofitted frame dissipated 233% more energy than the reference frame. In small drift ratios, the retrofitted frame exhibited a faster decay in the lateral stiffness; however, at large drift ratios, both frames showed a comparable stiffness degradation rate. Numerical simulations showed that the infill wall's lateral strength could alter the retrofitted frame's failure mode and significantly affect its force-displacement response.

Tie system to upgrade out‐of‐plane performance of infill masonry walls

AbstractThe objectives of this study were to investigate the out‐of‐plane behavior of unreinforced masonry (URM) infill walls and to identify the effectiveness of tie systems that were proposed to enhance the infill stability under both in‐ and out‐of‐plane effects. This study examined three types of tie systems: a full‐length tie system (prototype), a staggered tie system and a half‐length tie system. For this purpose, four 1/4‐scale, single‐story, one‐bay masonry infilled reinforced concrete (RC) frame specimens with and without the proposed tie systems were sequentially tested under in‐plane static cyclic loading and out‐of‐plane dynamic excitation. In the experimental study, two series of shaking table tests were conducted to investigate the out‐of‐plane behavior of the infill walls. The first series compared the fundamental out‐of‐plane performance of three proposed tie systems, and the second series verified the effectiveness of the full‐length tie system to prevent infill out‐of‐plane failure under an excitation simulating the severe floor response in medium‐rise buildings. The test results indicated the following: (1) the presence of the tie systems caused minor differences in the in‐plane capacity and ductility of each specimen, (2) the effectiveness of the full‐length and staggered tie systems was superior to that of the half‐length tie system, and (3) the full‐length tie system not only prevented the infill out‐of‐plane failure but also significantly reduced the infill damage under realistic excitation conditions. The above research outcomes provide a useful contribution of the infill to upgrade the seismic resistance of buildings.