Wall Panels Research Articles

Exploring the synergistic effects of graphene on the mechanical and vibrational response of kenaf/pineapple fiber‐reinforced hybrid composites

AbstractThe automotive, aerospace, and sports industries are increasingly utilizing hybrid composites made from natural fiber reinforcements. This study evaluated the performance of a composite made from kenaf and pineapple fibers, manufactured using the compression molding process, with graphene nanoparticles added at varying weight concentrations of 0.5, 1.0, 1.5, and 2.0 wt%. Results showed that adding 0.5 wt% graphene increased the tensile, flexural, and impact strength of hybrid composite by 133.75%, 90.24%, and 25.67%, respectively. Microstructural analysis revealed that graphene integration has enhanced the interfacial bond between the fiber and the matrix, creating resin‐rich areas. Furthermore, the free vibrational analysis indicated that graphene‐infused composites exhibited higher natural frequencies, improving their energy‐absorbing capabilities. Water absorption tests demonstrated that the inclusion of graphene reduced water penetration by improving interfacial bonding, minimizing voids, and decreasing surface energy, which limited water pathways in the composite. Furthermore, the composites with 0.5 wt% graphene showed a contact angle of 80.8°, indicating lower hydrophilicity compared to neat composites, which had a contact angle of 70.7°. This research emphasizes the advantages of hybrid composite materials derived from kenaf and pineapple fibers, specifically for applications in vehicle interiors and construction, including wall panels and separators.Highlights Hybrid composite was prepared using the compression molding process. Adding 0.5 wt% graphene improved the mechanical properties of composites. Hybrid composites with lower wt% graphene had higher natural frequencies. The composites with 0.5 wt% graphene had better water absorption properties.

Investigation into the flexural performance of novel precast sandwich wall panels

The paper focuses on investigating a novel sandwich panel, which incorporates extruded polystyrene foam boards placed between the inner and outer concrete panels. These are connected using various types of shear connectors to achieve a composite action, meeting the bending resistance requirements. To study the structural performance of the sandwich panels, three representative specimens were designed. These specimens employed different types of shear connectors, namely, steel truss connectors with inclined bars at 45°, and GFRP connectors with inclined bars at 45° and 30°, respectively. The specimens underwent full-scale testing using a step-by-step four-point loading method. The test results indicated shear-compression failure of the specimens, exhibiting consistent failure modes across all specimens, and a composite action in resisting bending moments. Based on theoretical stress–strain diagrams and considering the slip phenomenon between the concrete panel and the connectors, this paper establishes an analytical model. It can reasonably estimate the ultimate load-carrying capacity of sandwich insulation panels under shear-compression failure, which has implications for subsequent engineering applications.

Blast response and protection level of concrete composite wall panels made with recycled tyre fibres in a cement matrix

This paper investigates the blast response and protection level of a new blast-resistance wall panels made of Recycled Tyre Fibres Concrete (RTFC) as an exterior protective layer compositely connected to a concrete wall through experiments and numerical modelling. RTFC is a novel sustainable cement-based versatile composite, made with recycled non-biodegradable material (tyre rubber particles) in the form of composite fibres in a cement matrix, with applications in blast and ballistic protection that features high dynamic properties. Three composite wall panels were constructed and subjected to blast loads generated by Advanced Blast Simulator (ABS). Three different loading scenarios, each with an intensity capable of causing complete structural failure, were applied. The blast wave characteristics, such as the imposed overpressure and impulse, were measured alongside the deflection of the specimens. The wall specimens could withstand the blast loads with minimal damage. No cracks were observed in the RTFC layer, with only minor cracks appearing on the concrete side of the wall. The protection performance of the wall specimens was examined following UFC guidelines, revealing their outstanding resistance to blast loads. Moreover, in line with these guidelines, the composite wall panel is eligible for a High Level of Protection (HLoP) classification. Finally, a Single Degree of Freedom (SDOF) analytical model was developed for the wall panel to determine the Dynamic Increase Factor (DIF) of RTFC. The analysis resulted in a DIF value of 1.5, which was then incorporated into the numerical models of the walls. The accuracy of the DIF was validated by comparing the numerical results with experimental data, confirming its reliability.

Fuselage panel structural-acoustic optimization design of civil aircraft based on numerical analysis

Abstract During the design process of civil aircraft, it is necessary to achieve a high level of cabin noise control to improve cabin comfort. In addition to controlling the intensity of the main noise sources that affect the acoustic environment in the cabin, the acoustic optimization design of the fuselage wall panel structure is also required. In this paper, acoustic analysis software ACTRAN is applied to study the acoustic characteristics of typical structures of civil aircraft cabins. Boundary conditions, material density, and material damping are analyzed from the following main aspects: fuselage panels, thickness, density, reinforced frame design, etc., to study the acoustic barrier performance of typical fuselage panel structures, put forward design suggestions for fuselage panels, and guide the acoustic optimization design of civil aircraft structures.

A Streamlined Laser Scanning Verticality Check Method for Installation of Prefabricated Wall Panels

A Streamlined Laser Scanning Verticality Check Method for Installation of Prefabricated Wall Panels

Experiments and FE Modeling on the Seismic Behavior of Partially Precast Steel-Reinforced Concrete Squat Walls

This paper proposed an innovative precast steel-reinforced concrete (PPSRC) squat wall to simplify on-site construction. In PPSRC squat shear walls, the hollowly precast RC wall panel can be assembled on-site through the pre-erected steel shapes, and the boundary cores will be filled using fresh concrete together with the slab system. The seismic performance of PPSRC squat walls, influenced by different construction techniques (cast-in-place vs. precast) and steel ratios, was examined through pseudo-static experiments on three specimens. Some key performance indicators, including hysteretic behavior, skeleton curves, stiffness degradation, energy dissipation, and load-carrying capacity, were analyzed in detail. The test results indicated that all the PPSRC squat walls failed in typical shear failure, and no significant slippage between the precast and fresh concrete sections was observed during the loading process, indicating that the composite action could be fully achieved via the novel throat connectors. In addition, the PPSRC squat walls could achieve comparable seismic performance compared with that of cast-in-place SRC shear walls (the peak load of the PPSRC squat wall only increased by 0.26% compared with the control specimen), and the load-carrying capacity and deformability could be enhanced by increasing the steel ratio in the boundary elements. Finally, an elaborate finite element model was developed and validated using ABAQUS software. The parametric analysis of the concrete strengths of precast and cast-in-place parts and the axial load was conducted further to investigate the seismic performance of PPSRC squat walls.

Axial buckling resistance of cold-formed steel built-up I-section wall panels with single- and double-layer sheathing configurations: experimental and analytical studies

ABSTRACT This paper presents experimental investigation of the axial behaviour of built-up (BU) (I-section) cold-formed steel doubly-symmetric channel with single-/double-layer sheathing on both sides configuration. Fifteen (15) monotonic concentric axial compression tests were performed on 7-BU sections with single-layer sheathing, 7-BU sections with double-layer sheathing, 1-BU section stud without sheathing. The experiments aim to enumerate ultimate axial strength, buckling interactions, failure pattern and strength enhancement due to sheathing for BU section stud members. The novelty of the study is that, for the first time an attempt is made to investigate the axial behaviour of single-/double-layer sheathed BU section panels using seven different sheathing boards. Results indicate large range of deformation behaviour, with local-global and distortional-global interaction buckling phenomena. Failure is also observed due to failing of screws in specimens with sheathing of thickness ≥ 9 mm and modulus of elasticity > 6400MPa. Also, for the first time, efficacies of four semi-analytical methods based on rational extension of direct strength method (DSM) are presented. Results suggest the insufficiency of current AISI design specifications, whereas predicted results obtained using the new modified DSM methodology are within the adequate variation range as the adopted methodology considers desired buckling interaction. The efficacy of the recommended design methodology is verified through reliability analysis.

Robustness of Dry‐Assembled Precast Wall and Coupled Wall‐Frame High‐Rise Structures With Voided Prestressed Slabs

ABSTRACTPrecast concrete structures are recognized among the structural typologies that may mostly suffer from progressive collapse as a consequence of local unpredicted damage, also due to past accidents occurred in buildings employing old precast technologies neglecting the basic robustness criteria and characterized by poorly detailed and/or executed joints and connections. Although vertical ties may relatively easily be provided in both frame and wall panel structures by employing ductile connection devices, dry‐assembled precast systems avoiding concrete pouring in the whole superstructure typically struggle to provide horizontal ties as strong as required by the current standards concerning progressive collapse, in which they are not fully framed yet. Nevertheless, these systems may exploit alternative sources of robustness to stop collapse progression arising from their structural arrangement, the shape of the slab elements employed, and the slab mechanical connections. This article presents the results of a numerical investigation focused on the structural behavior of a dry‐assembled precast floor system consisting of prestressed box‐section slab elements employed in either wall panel or coupled wall‐frame structural systems following the loss of one or multiple primary load‐bearing vertical elements. Nonlinear static simulations of different loss scenarios occurring in prototypes of 100‐m‐tall high‐rise buildings were carried out based upon spread plasticity modeling of the structural elements and experimentally calibrated nonlinear behavior of mechanical connections.

Physical, Mechanical, and Flammability Properties of Wood-Plastic Composites (WPC) Containing Beech-Wood Flour and Flame-Retardant Additives.

This study aims to develop a recyclable, economical, and flame-retardant composite material using polypropylene, beech flour, tetrabromobisphenol A bis (TBBPA), and antimony trioxide (ATO). Flame-retardant additives (TBBPA and ATO) were initially added into polypropylene at different rates, and masterbatch (MB) samples were produced by the extrusion method. Subsequently, different percentages of wood flour (10%, 15%, 20%, 25%, and 30%) along with 60% MB were added to the polypropylene to create wood-polymer composites (WPC) using the injection method. The TBBPA, ATO, and wood flour were introduced through side-feeding hoppers during injection to ensure a homogeneous distribution within the WPC. Physical, thermal, and mechanical tests were conducted on the WPC samples. Additionally, TGA, FTIR, and SEM analyses were performed. The results indicated that the optimal ratios for TBBPA and ATO additives were 20% and 10%, respectively. It was observed that increasing the wood flour content in the WPC samples led to enhanced density, water absorption, hardness, impact, and abrasion resistance. Conversely, MFI, bending strength, and tensile strength decreased with higher wood flour content. It was observed that WPC samples exhibited flame resistance up to 725 °C. The produced WPC materials can be used in flooring applications, interior furniture, decorative wall panels, and aesthetic structural elements due to their fire behavior, good mechanical properties, low water-absorption rates, and aesthetic appearance.

Modular steel panel for walls: life cycle environmental impact, life cycle cost, and potential for material circulation

The impacts of civil construction are widely recognized and justify the transition from a linear to a circular economy. Furthermore, with building users increasingly demanding greater adaptability, strategies such as modularity and flexibility to adapt to changing uses are being discussed. Modular wall panels allow quick installation and have the potential for disassembly, refurbishment, reuse, and recycling. We evaluate a modular steel panel system in two Brazilian case studies through life cycle assessment (LCA), life cycle cost (LCC), and building circularity index (BCI). The study applies the circular reuse and remanufacture, recycling, and life extension strategies for internal and external walls. For the external panel, the life extension strategy (SE02) stands out positively in all impact categories, with the lowest environmental impact and costs. However, the SE02′s BCI does not have the best result. The second best option is reuse (SE03), with the highest percentage of circularity. Furthermore, the differences between SE02 and SE03 are reduced in several impact categories, and the sensitivity analysis (transport, damage, and the number of reuses) shows that the differences could be even smaller. For the internal panel, life extension (SI02) and reuse (SI03) scenarios are the best options. Recycling (SI04) has the highest environmental impact and the best potential for circularity. BCI communication must be aligned with LCA and LCC, such that an increase in circularity is accompanied by a decrease in environmental impacts or with infeasible costs, especially for developing countries.

Multimodal optimization of concrete mix design for sustainable load bearing wall panels: Mean-mix − Artificial Intelligence − experimentation fusion

This work used abundant database to intelligently select a mix-proportion of conventional OPC and fly ash (FA) based concretes. First, data was sorted and bifurcated according to the grades of concrete, and a mean mix-design (MMD) approach was proposed for selecting constituents. Afterward, both data types were trained using an artificial intelligence (AI) tool, and strength was predicted for trained sets and testing sets of data. It was further compared with the MMD approach for considering a 30 MPa strength. Moreover, experiments were designed for 30 MPa targeted strength by ACI and MMD methods. It was observed that MMD, AI, and experimentation approaches have close correspondence for selected targeted strength. However, ACI-based mix-design overestimated the strength, resulting in higher costs and CO2 emissions than their counterparts. It has also been observed that FA-based concrete has a similar cost to lower-grade conventional concrete but has lesser CO2 emissions. Furthermore, a multi-objective optimization model was proposed for intelligent mix design by integrating strength, cost, and CO2 emissions. It was revealed that the proposed MMD proportions of constituents are among the top-ranked intelligent mixes, thus verifying the proposed approach. Finally, the wall panel was developed of size 600 × 300 × 125 mm using conventional concrete and FA-based concrete, and it fulfills the performance requirement of masonry defined by standards. The cost of masonry with wall panels is 35 % lower than conventional brick masonry, and CO2 emission was 68 % lower, respectively.

Experimental Analysis of the Mechanical Behavior of Shear Connectors for Precast Sandwich Wall Panels When Subjected to the Push-Out Tests

Precast concrete sandwich panels consist of two outer layers connected by a central connector and an inner insulating layer that enhances thermal and acoustic performance. A key challenge with these panels is eliminating thermal bridges caused by metallic connectors, which reduce energy efficiency. PERFOFRP connectors, made from perforated glass fiber-reinforced polymer (GFRP) sheets, have been proposed to address this issue. These connectors feature holes that allow concrete to pass through, creating anchoring pins that enhance shear resistance and prevent the separation of the concrete layers. This research aimed to evaluate the effect of the diameter and number of holes on the mechanical strength of PERFOFRP connectors. Three diameters not previously reported in the literature were selected: 12.70 mm, 15.88 mm, and 19.05 mm. A total of 18 specimens, encompassing 6 different configurations with varying numbers of holes, underwent push-out tests. The most significant resistance increase was a 15% gain over non-perforated connectors, observed in the configuration featuring three holes of 19.05 mm. The connections exhibited rigid and nearly linear behavior until failure.

Numerical and experimental investigation on angle multiple slit bolted connections for precast wall panels

Flat Multiple Slit Devices (MSDs) have been introduced in steel constructions located in earthquake-prone areas as compact hysteretic dampers connected to braces, and were further proposed to be employed also in other structural typologies, including aligned precast concrete walls. Nevertheless, similar angle connections needed for horizontal joints of orthogonal walls are not tackled in literature. The shape of MSDs, obtained by selective weakening by removing part of the steel area of flat plates, may allow to attain a highly ductile and stable dissipative behaviour, given local plate buckling is avoided, protecting the bolted joints through capacity design. Laser cutting as an alternative to mechanical milling introduces the possibility to easily optimise the shape of the slits in order to attain better performance under laterally imposed cyclic load. This paper analyses the application of right-angle-bent MSDs for the horizontal connection between orthogonal precast walls typical of panel structures with rigid diaphragms. In particular, bolted angle plates with hourglass-shaped multiple slits obtained after laser cutting are investigated numerically via non-linear finite shell elements and experimentally with original cyclic tests. The effect of the aspect ratio of the plate and of the restraint condition, possibly affecting the performance under imposed shear deformation due to the presence of the bent corner, is investigated by parametric analysis. Finally, general design rules and recommendations are presented.

Influence of diagonal reinforcement in grouted vertical joints between precast concrete wall panels, part I: Experimental investigation

AbstractMulti‐storeyed buildings are constructed using precast concrete large panels. Although the resistance to lateral loads during an earthquake can be provided by the walls, the vertical joints between the panels remain the weak links. Conventionally, a grouted vertical joint between precast panels is achieved using minimum number of overlapping transverse horizontal U‐bars or looped wire ropes from the adjacent panels, with a holder bar at the overlap, and subsequent grouting of the gap. It was observed that under in‐plane lateral loads, the shear behavior of such joints, especially those with looped wire ropes, is brittle. This paper presents a study to improve the behavior of conventional joints by introducing diagonal reinforcement (DR). Toward this, 13 specimens were tested under monotonic loading and 2 specimens were tested under quasi‐static cyclic loading. The parameters investigated were the types of transverse joint reinforcement, types and strengths of diagonal reinforcement. The compressive strengths of panel concrete and joint grout were kept similar to industry practice. The specimens with DR showed substantial increase of the shear strength and load retention beyond the peak. The presence of conventional transverse joint reinforcement in addition to DR, increases the retention capacity of the joint. Thus, the behavior of a joint with DR was found to be stronger and more ductile.

Estimation of random incidence sound transmission loss of panels based on normal incidence sound transmission loss measurements

The performance of building sound insulation is an important parameter for evaluating the quality of construction projects. So far, the sound insulation performance testing of building walls requires the installation of large-dimensioned wall samples in specialized sound insulation laboratories, which is time-consuming and costly. If small-dimensioned components of the wall panels can be applied and quickly tested at the project site, it could significantly improve efficiency and reduce costs. To address this issue, this paper investigates a method for estimating the random incidence sound transmission loss of wall panels based on the measurement of the normal incidence sound transmission loss of corresponding small samples. Initially, the sound transmission loss of single-layer and composite structures is theoretically analyzed based on the theories of Equivalent Single Layer method and Layer-Wise method. Subsequently, the random incidence sound transmission loss is estimated by the normal incidence sound transmission loss. The methodology for estimating the random incidence sound transmission loss of wall panels proposed in this study offers both a practical approach and theoretical support for the rapid assessment of the sound insulation performance of building walls. This study is of great significance for improving the quality of construction projects and inspection efficiency.

Smart Home

The concept of a smart home integrates wireless electronic systems that connect household devices to a central interface, enabling remote control via smartphones or wall panels through Wi-Fi networks. This paper explores the core components of smart homes, including smart devices such as speakers, thermostats, lighting, and security systems, as well as the role of mobile applications in managing these devices. The paper discusses the various applications of smart homes, from home automation and security monitoring to energy management and health-focused initiatives.

Study on seismic performance of a novel connection for exterior wall panels

In order to avoid the damage of the external wall panel and connecting joints caused by the incompatibility between the steel structure and the external wall panel under earthquake loads, as well as to control the interaction between the structure and wall panel to ensure favorable impacts on the main structure, a new connection for external wall panel is proposed. This connection combines the features of the sliding connection and the energy dissipating connection. To investigate the deformation behavior, failure modes, and energy dissipation capacity of the connection, a total of ten specimens with different parameters were designed for cyclic loading. The results indicate that the new connection dissipates energy through bending plastic deformation and pull-bending plastic deformation of the side plate, demonstrating excellent deformation and energy dissipation capacity with noticeable post-yield strengthening effect. Additionally, the effects of different geometric parameters on the initial stiffness, yield load, bearing capacity and hysteretic properties of the connections are also analyzed. Finally, based on the theoretical model of the space rigid frame, the calculation formula of the characteristic parameters at elastic stage of the joint is proposed by the assumptions of ignoring torsion, axial and shear deformation, which is validated by the test results and finite element simulation.

Experimental study on non-load bearing multi-span sandwich wall panels for blast mitigation

Sandwich wall panels are known for their ability to provide resistance over a wide deformation range, rendering them suitable for blast resistance applications. These panels consist of layers of concrete with an insulating core, offering a structural solution with enhanced performance. Quasi-static testing was conducted on multi-span sandwich wall panels with intermediate connections to evaluate their behavior under controlled loading conditions. A total of twelve two-span details were examined and selected to match the standard designs employed in the Tilt-Up Construction (TCA) and Prestressed/Precast Concrete Industry (PCI). Among these details, three belonged to the TCA type with two duplicates, while the remaining two were representative of PCI designs with three duplicates. The results obtained from the quasi-static testing indicate that insulated sandwich wall panels possess sufficient deformation capability to meet the current blast response criteria. To assess the findings of the static experiments to the prevailing response limits, the outcomes were distilled into a multi-linear static resistance analysis. The findings support the use of insulated precast concrete (PC) sandwich wall panels, highlighting their suitability for blast-resistant designs within the constraints of current blast design limitations. Specimens with Halfen connectors showed 32 % higher energy absorption and a 58 % advantage over Stud connectors, making them superior for robust blast resistance applications.

Experimental investigation on shear performance of ECC sandwich insulation wall panel with GFRP connectors

The problem of high energy consumption in buildings is becoming increasingly prominent. Sandwich insulation wall panel is used to reduce the heat loss of building because it has the same life span as the main structure of the building. Engineered Cementitious Composites (ECC) is a material with significant multi-crack cracking ability and strain hardening characteristics, and replacing ordinary concrete with ECC as the inner and outer plates of sandwich insulation wall panels contributes to solve the problems of easy cracking and poor durability of the plates. Therefore, starting with the form of GFRP connectors, this thesis studied the influence of different connector forms on the shear performance of ECC sandwich insulation wall panel through experiments, and evaluated its safety. The results show that the specimen with X-shaped connector had the highest vertical shear stiffness and bearing capacity, but its lateral shear stiffness and bearing capacity were very low, which could not be used as a two-way shear connector. The shear stiffness and bearing capacity of the I-shaped connector and the modified X-shaped connector were similar, but the toughness index of the modified X-shaped connector was much higher than that of the I-shaped connector. All connectors could meet the requirements of relevant specifications for shear bearing capacity and deformation. In comparison, the shear performance of the modified X-shaped connector was more excellent.

Thermally anisotropic building envelope for thermal management: finite element model calibration using field evaluation data

The thermally anisotropic building envelope (TABE) is an active building envelope that redistributes thermal loads in response to weather conditions and building energy demand. Conductive layers throughout the TABE distribute low-grade heat among hydronic loops, altering heat flow direction and intensity. Finite element models of TABE roof and wall panels were developed and calibrated using field evaluation data. The calibration results showed that heat flux differences between the experimental data and finite element models averaged −0.42% and 3.57%, with a maximum mean square error of 1.78 and 3.96 for roof and wall panels, respectively. A reduction in heat flux from the environment to the building living space over the entire testing period (weeks in July/August) was found to be 85% for roof panels and 335% (load reversed) for wall panels. These results indicate TABE can effectively harness low-grade thermal energy sources to achieve high energy efficiency and promote demand-side management.