Infilled Frames Research Articles

Coastal wave-energy attenuation by artificial wooden fences deployed for mangrove restoration: an experimental study

By offering natural protection along offshore wetlands, mangroves play a crucial role in providing great ecological and economic benefits to local communities. However, mangroves are currently facing an increasing threat of decline worldwide due to widespread human activities and climate change. Recently, eco-friendly wooden fences have been deployed along eroded coasts for mangrove restoration projects, and these fences have the capability to attenuate incoming waves and strengthen sediment deposition in new habitats for mangrove colonization and persistence. However, the design and performance of the fences used can differ substantially among different projects; therefore, it is necessary to study the major factors affecting the wave dissipation performance of these fences and find out a more effective structural design. Thus, we focus on two distinct types of fences with and without porous infill to study the function of infill porosity and frame density, and physical experiments of waves transmission through the fences were carried out in a wave flume, in which nine wooden fences with varied infill porosities (0.60–0.90) and frame densities (0.40 and 0.70) were predetermined to measure the wave transmission, reflection, and wave dissipation. In total, 180 experimental runs were conducted under 18 wave conditions with different wave steepness. The results showed that the fence with a lower infill porosity appears to increase wave transmission coefficient that comes at a cost of a higher reflection coefficient and less wave-energy dissipation inside the fence, and the fence with the highest porosity infills (90%) is nearly equivalent to the fence without any infills but a dense frame in terms of wave damping performance. Moreover, the wave transmission through both fences with and without infill can be remarkably affected by incoming wave steepness. The outcome of the research is not only indicating the importance of the appropriate infill porosity in attenuating incoming waves but also guiding the design of mangrove restoration project in offshore wetlands.

Evaluation of modelling uncertainties impact in older infilled frame RC structures

The seismic response of infilled frame reinforced concrete structures is affected by different sources of aleatory and epistemic uncertainties and is particularly sensitive to the modeling parameters evidenced by reported numerical and analytical studies. In the current study, a probabilistic sensitivity analysis is performed by nonlinear static (PNSA) and nonlinear dynamic analyses (PNDA) on a base-case infilled frame structure incorporating structural (beam, column) and non-structural (masonry infill) components behavior. Therefore, the state-of-the-art models of the most effective sources of nonlinear response employed herein as fiber section to depict the axial-moment interaction in frame components, bi-diagonal eccentric strut to capture the cracking and crushing of masonry infill, and the shear failure in columns caused by infill-frame interaction. Finally, results are illustrated by tornado plots incorporating probabilistic sensitivity to material and component parameters for operational (O), damage (D), life safety (L), and collapse (C) limit states. Results state that the building response is significantly affected by the modeling parameters of infill characteristics, mass source, and the damping of the structure.

Seismic performance of RC frames with self-centering precast post-tensioned connections considering the effect of infill walls

This paper presents the seismic performance evaluation of self-centering precast post-tensioned concrete (SCPPTC) frames with infill walls. The SCPPTC connection system consists of all-steel bamboo-shaped energy dissipaters (SBED) and prestressed tendons, which provide energy dissipation capacity and self-centering capability, respectively. Using modeling parameters calibrated with experimental tests, nonlinear numerical models of SBED, SCPPTC connection, infill walls, and 2D SCPPTC frames were developed in OpenSees, to compare the performance of the structures with different types of infill wall layouts. Nonlinear static pushover and incremental dynamic analysis (IDA) were performed to study the effect of infill walls on the overall response of SCPPTC frames, in terms of stiffness, strength, maximum interstory drift ratio,θmax, the maximum residual interstory drift ratio, θr,max, and the normalized post-tensioned force. Using the IDA results, the study also developed fragility curves and estimated the collapse margin ratios. The results demonstrated that the shear strength of the SCPPTC frame was improved from 4.19% to 12.2%, and the initial secant stiffness of the SCPPTC frame was augmented from 22.9% to 88.3% with increasing filling rate. The totally infilled SCPPTC frame (SCPPTC-ToI) exhibits a 19.86% lower θmax than that of pilotis-infilled SCPPTC frame (SCPPTC-PiI) under rare earthquakes, and the maximum prestress of SCPPTC-ToI was also 7.14% lower than that of SCPPTC-PiI. With the increase in filling rate, θr,max increased by a maximum of 120.45%. The pronounced soft layer led to the highest failure and collapse probabilities of SCPPTC-PiI among all SCPPTC frames at the same performance level.

Numerical evaluation of Masonry-Infill Frames: Analysis of lateral strength and failure modes on meso scale

This study investigated the failure modes of masonry-infilled frames, a common structural system in modern construction. By analyzing 6,496 frames and considering variables such as the height-to-width ratio and compressive strength of the masonry prism and the plastic moment capacity of the section of the frame, equations were derived for various failure modes of masonry-infilled frames. The study found that the lateral strength of masonry-infilled frames with a height-to-width ratio ranging from 0.2 to 1.2 is primarily dependent on the compressive strength of the masonry prism. The derived equations showed good agreement with previously established correlations, indicating their accuracy and reliability. These findings provide valuable insights into the lateral strength of infill masonry frames and can assist in their design and assessment. However, it is important to note that the study was limited to analyzing the behavior of the frames under static loading conditions and within a specific height-to-width ratio range. Overall, this study contributes to the understanding of the lateral strength of infill masonry frames and offers a practical tool for their design and evaluation.

Testing of Damaged Single-Bay Reinforced Concrete Frames Strengthened with Masonry Infill Walls

Despite achieving consensus and having current knowledge on the behaviour and contribution of masonry infill walls, there remain unresolved issues regarding their nonlinear behaviour as a method for strengthening existing reinforced concrete (RC) frames with effective modifications, primarily infills and the interconnection of infills and frames. The challenge for safely and economically designing frames with competent walls is to utilise the stiffening benefits while ensuring that the increased lateral forces and reduced drift capacity do not hinder performance. This study aims to investigate the potential of using masonry infill to strengthen previously slightly damaged RC frames. Experimental tests were conducted on previously slightly damaged RC frame specimens infilled with vertically hollowed-clay and solid-clay masonry units, connected to the frame elements using traditional methods (i.e., avoiding the use of modern composite materials). These strengthened infilled frame structures were subjected to constant vertical and cyclic lateral loading, which revealed improved stiffness, strength, and damping characteristics, enhancing their overall behaviour. As the main novelties, the study found that when damaged RC frames were strengthened with masonry infill walls, their performance resembled that of undamaged infilled RC frames. The strengthened infilled frame structures exhibited enhanced stiffness, strength, and hysteretic damping. The increase in stiffness was observed regardless of the type of masonry units and the strengthening technique employed. However, the improvements in strength and hysteretic damping were influenced by the specific masonry units, particularly their robustness, and the chosen reinforcement method.

Mechanical Behavior of Two-Side Bolted Steel Plate Shear Wall Considering Top-Seat Constraints with Frame Beams

A steel plate shear wall (SPSW) is a useful component for resisting lateral action. To improve the performance of frame columns, some studies focus on a two-side connected SPSW, in which the wall plate is not connected with the frame columns. However, few studies conducted on a two-side connected SPSW consider the effect of frame constraints or the connections between the infill plates and frame beams. In this study, by using finite element modeling (FEM), two unstiffened SPSW models with two-side fixed connections and six unstiffened SPSW models with two-side bolt connections were simulated. Their performance under the presence of out-of-plane frame beam flange constraints and different numbers of bolts between the infill plates and frame beams was analyzed. The mechanical performances such as hysteretic behaviors, the capacity of energy dissipation and the out-of-plane deformation of the members were investigated by applying monotonic and cyclic loading. The results revealed that non-negligible deformation would be generated at the lateral border of the bolt connections and that the out-of-plane deformation of the frame could be significantly affected by constraints. These findings can guide the engineering design of SPSWs in the future.

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.

INFLUENCE OF DIFFERENT INTERFACE MATERIALS AND OPENINGS IN INFILL OF REINFORCED CONCRETE INFILLED FRAMES

This study analytically investigates the behaviour of trapezoidal infilled frames (TIFs) with brick masonry infills having openings and various interface materials between the brick panel and reinforced concrete frame. Single-storey single-bay frame specimens are analysed under in-plane static loading. For this investigation, the optimum angle of the column inclination for the trapezoidal frame must be determined in terms of maximum lateral stiffness. The optimum angle must be further analysed and compared with rectangular bare and infilled frames, with various materials of the interface. This infilled frame is extended to analyse the openings in the infill further. To study the effects of openings in infilled panels, TIFs with different sizes and positions of window openings are analysed and compared with the rectangular frame. This study further analyses three different combinations of interfaces and determines the intermediate stiffness of the frame combination. The main focus of this investigation is to reduce the high rigidity of the TIF leading to high base shear. It is found that, the infilled frame is stiffer than the bare frame, and the cement mortar interface is stiffer than the lead–cork interface. This research uses ABAQUS software, a finite element analysis program, for expanding the observational analysis.

Experimental study on the seismic performance of a cold-formed thin-walled steel–concrete composite column-H steel beam frame

For lightweight steel frame structures consisting of steel H-beams and cold-formed steel columns filled with concrete, seismic performance comparison tests and numerical simulation analyses were performed for bare and infilled frames. The effects of the lightweight wall panels, the axial compression ratio and the wall thickness of the steel sections of the columns on the seismic properties of the structure were investigated. The failure of the bare frame was concentrated in the weld fractures at the beam-column joints. When the wall panels were embedded in the frame, the damage was concentrated at the corners and edges of the wall panels and the connectors. The wall panels significantly improved the initial stiffness of the frame, early energy dissipation and resistance, and the wall panel energy dissipation rate was initially as great as 91%. As the axial compression ratio increased, the resistance of the structure significantly decreased. Under monotonic loading, the resistance on the structure with an axial compression ratio of 0.4 was reduced by nearly 44% compared to the structure without axial compression. Increasing the wall thickness of the steel sections of the columns increased the load-bearing capacity of the structure, but the increase diminished with increasing wall thickness.

Out-of-Plane behavior of clay brick masonry infills contained within RC frames using 3D-Digital image correlation technique

The present study investigated the out-of-plane (OOP) behavior of traditional solid clay brick masonry-infilled reinforced concrete frames for different slenderness ratios, bonding patterns, and connection details to assess the development of arching mechanism, infill-frame interaction, and failure mechanisms. Full-field strain and crack width analysis, failure progression, and out-of-plane deformation characteristics were evaluated using a non-contact 3D-DIC (digital image correlation) technique. The experimental investigation ascertained that full-brick thick lower slenderness ratio (13.4) specimens observed higher capacity (3.7 times), deformation ability (>1.2 times), and energy dissipation characteristics (>3.5 times) compared to half-brick thick slender (28.8) specimens. The presence of tie bars enhanced the stability of the wall against out-of-plane failure. However, it did not significantly modify the load and deformation behavior in the peak and post-peak stages. The OOP deformation profiles, arching mechanism, and the distributed damage in infill in lower slenderness ratio specimens, which led to higher OOP lateral load resistance, were precisely captured using the 3D-DIC technique. The increase in width of the cracks (1.6–2.9 times) in Flemish bond (lower slenderness ratio) specimens compared to their running bond counterparts was accurately appraised using the DIC. Based on the experimental results, a unified out-of-plane lateral load–deflection idealized model was proposed. The appropriateness of the proposed model was further verified by comparing it with previously developed models and experimental studies. The research study revealed that the out-of-plane lateral load behavior of infilled frames was significantly modified due to strong and stiffer solid clay masonry, considering different structural bonding patterns and slenderness ratios. The 3D-DIC technique was found to be a resourceful tool for comprehending the deformation and damage characteristics of infilled frames, especially under out-of-plane lateral loads.

Parametric study on the collapse probability of modern reinforced concrete frames with infills

This study aims to compare the collapse probability of reinforced concrete infilled frames designed in accordance with modern Indian seismic codes. Multiple versions of bare and infilled (both fully and partially) frames are considered. A total of 33 frames are divided into eight sets based on the parameter being varied, namely, the quality and thickness of infills, design code, aspect ratio, and number of stories. The collapse probability is evaluated through multiple stripe analysis with eight stripes corresponding to different return periods. A set of 40 ground motions, consistent with the site-specific uniform hazard spectra corresponding to each return period, is selected. Results suggest that the frames designed for pre-2016 Indian codes perform considerably worse than those designed for post-2016 Indian codes, which are on par with other national codes. The effect of collapse probability of addition of infills to bare frames is found to be negligible to significantly negative depending on factors such as adopted design code, relative strength of infill strut to columns, aspect ratio, and number of stories. Four-story frames perform worse than 8-story frames. Interestingly, the 8-story open first story frames, designed for modern codes, are not found to be significantly more vulnerable than their fully infilled counterparts.

Effect of thermal expansion on three-dimensional reinforced concrete frames under high temperature

When exposed to high temperatures, reinforced concrete members undergo major changes in their properties which in turn affects their structural performance. Fire accidents in frame structures at local or global level may lead to collapse of structures. Structural fire has dire consequences like collapse of structures, colour changes, spalling of concrete and failure of essential elements. It is essential to study the conduct of reinforced concrete frame under thermal expansion in order to understand fire-induced collapse of concrete structures. This study observes how a three dimensional single-bay single-storey reinforced concrete frame is performed under thermo-mechanical analysis in ABAQUS (FEA). The paper aims to note the effect of slab and infill wall with respect to thermal expansion. The paper also discusses the main findings regarding the structural performance, structural leading conditions and structural stiffness of the reinforced concrete frame with slab and infill wall under thermal expansion. The results found that the infill frame has better stiffness and performs well under fire conditions.

Impact of ground-motion duration on nonlinear structural performance: Part II: site- and building-specific analysis

This study’s Part I proved that ground-motion duration could play an important role when assessing the nonlinear structural performance of case-study inelastic single degree-of-freedom systems. However, quantifying duration effects in many practical/more realistic engineering applications is not trivial, given the difficulties in decoupling duration from other ground-motion characteristics. This study’s Part II, introduced in this article, explores the impact of duration on nonlinear structural performance by numerically simulating the structural response of realistic case-study reinforced concrete bare and infilled building frames. Advanced computational models incorporating structural components’ cyclic and in-cycle strength and stiffness deterioration, and destabilizing [Formula: see text] effects are used. The proposed methodology relies on the generalized conditional intensity measure approach to select ground motions. This allows selecting records consistent with the seismic hazard at a target site, both in terms of spectral shape and duration. Those are employed as input to cloud-based nonlinear structural response analyses. Variance analysis is used to quantify the impact of duration on structural response. Furthermore, vector-valued fragility and vulnerability models alternatively using peak- and cumulative-based engineering demand parameters are derived. Results show that higher damage/loss estimates can be attained as ground-motion duration increases. Relative differences up to 44% are found in fragility median values for a pre-code reinforced concrete infilled frame when comparing scalar and vector-valued fragility models conditioned on average pseudo-spectral acceleration and significant durations up to 35 s.

Framework to assess the seismic performance of non-engineered masonry infilled RC frame buildings accounting for material uncertainty

Non-engineered construction accounts for more than half of the building stock in low and middle-income countries. A significant portion of these buildings is constructed using masonry infilled reinforced concrete (RC) frames with inadequate seismic detailing. This type of construction is prone to high levels of variability in the material properties, posing a significant challenge in their seismic performance evaluation. This research proposes a framework to assess the seismic performance of non-engineered constructed masonry infilled RC frame buildings, which considers the material uncertainty. A four-stage procedure based on Monte Carlo simulations is introduced, wherein engineering demand parameters and seismic performance are expressed in terms of probability distributions. The framework is demonstrated using a non-engineered housing archetype located in Sincelejo, Colombia. The results showed that the framework allows capturing the uncertainty in the materials construction variability of non-engineered houses. The results also showed that mean values of material properties may lead to significant errors in the seismic performance assessment of non-engineered constructed masonry infilled RC frames. The differences between the predicted minimum and maximum exceedance probabilities of a damage state can be greater than 80%.

Pseudodynamic Tests and Numerical Modelling for Damage Analysis of Infilled RC Frames

ABSTRACT Full-scale experimental tests are still needed to enhance knowledge on the seismic response of existing reinforced concrete buildings and to calibrate numerical models aimed at predicting damage. This study deals with pseudo-dynamic (PSD) tests and numerical modeling of full-scale multi-story infilled RC frames with different infill-to-frame connections. Nonlinear numerical models are calibrated using the experimental results at frame level and validated against the results of time-histories in terms of displacement demand, hysteretic response, and attained damage. This model is extended at building level and used to predicted damage to infills. The comparison with damage observed during post-earthquake inspections is reported and discussed.

Artificial neural network prediction of window openings and positions in reinforced concrete infilled frames with pneumatic interface

Artificial neural network prediction of window openings and positions in reinforced concrete infilled frames with pneumatic interface

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.

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.

Non-Linear Static Analysis of Concrete Structure using Brick Infill Material: A Review

Abstract: The properties of masonary and its constitutive materials were reviewed, giving special emphasis to those aspects which contribute to a better understanding of the strength mechanism. Computer based procedures were developed for the rational evaluation of the strength of masonry subjected to compressive and shear stresses. The effect of pinching of the hysteresis loops in the response of infilled frames subjected to earthquakes was investigated. This paper was prepared to study various research work related to the Seismic analysis of reinforced concrete structures using brick as an infill material.

Numerical Modeling Technique of Damage Behavior of MaSonry-Infilled RC Frames

The damage pattern of masonry-infilled reinforced concrete (RC) frame structures in earthquake events is complicated, and understanding the detailed failure behavior of these structures and modeling it accurately has been a challenging task. In this paper, the extended finite element method (XFEM) is introduced to reproduce arbitrary cracks initiating and propagating in concrete frame and masonry units, combined with interface elements to model various behaviors of masonry-infilled RC frames. Within the finite element analysis program FEAP, a user element subroutine is adopted for the incorporation of XFEM and two types of extended finite elements with and without crack tip enrichments are built to simulate the behavior of concrete material for frame members and masonry blocks for the infill panel, respectively. In addition, a macro command is created to check the crack-propagation criterion and update crack and enrichment information. Furthermore, numerical examples are performed with existing test data, which reveal the efficiency of the implementation procedure. A comparison of the analytical and experimental results show that the proposed modeling can be used to predict the crack and failure process and the load-bearing capacity curves of the structures and reflect accurately the interaction of masonry infill and RC frames.