Cladding Systems Research Articles

Equivalent spring model and efficient numerical strategy for simulating mechanical performance of seam-clip connections in aluminum alloy high-vertical standing seam metal cladding systems

The equivalent spring model has been validated as effective in simulating the mechanical performance of seam-clip connections in typical steel high-vertical standing seam metal cladding systems (SSMCSs). To enhance its applicability, this study further refines the equivalent spring model by developing thickness-related stiffness calibration models and an efficient numerical strategy for seam-clip connections in the aluminum alloy SSMCSs. Tensile tests are initially conducted to analyze the material properties of specimens with three commonly used thicknesses. Subsequently, the mechanical performance of the aluminum alloy seam-clip connections with different thicknesses is systematically studied, followed by the development of thickness-related stiffness calibration models. The tensile test results reveal notable nonlinearities and variability in the mechanical performance. To simulate this mechanical performance equivalently in the finite element (FE) model using data from tensile tests, an efficient numerical strategy is developed. This strategy involves methods for implementing simplified connections to establish the equivalent spring model and techniques for efficiently creating these simplified connections. It is found that both connectors and spring connections with calibrated parameters from tensile tests can effectively replicate the mechanical performance of seam-clip connections. To further validate the effectiveness of the equivalent spring model and the efficient numerical simulation strategy, a comparison of structural responses of the double-span sheet module (DSSM) obtained from tests and FE analysis is performed. The results reveal that all simulated structural responses on the DSSM with three common sheet widths align well with the corresponding experimental results. This highlights the feasibility and efficacy of the equivalent spring model and efficient numerical strategy in simulating the mechanical performance of seam-clip connections and delving deeper into the structural responses of the aluminum alloy high-vertical SSMCSs.

Impact of in-core fuel management on the radial peaking factor in the APR-1400 with accident-tolerance fuel cladding

This study provides an in-depth examination of the initial, transition, and equilibrium cycles of the APR-1400 reactor core, focusing on reference fuel cladding and ATF cladding systems. This research highlights the importance of in-core fuel management strategies, particularly checkerboard configuration, in maintaining safe and efficient reactor operations. The radial peaking factor (RPF) is an essential parameter in evaluating the core configuration, and a study demonstrated that the RPF can be effectively controlled below the threshold of 1.85 through careful fuel reshuffling and introducing new fuel assemblies. Key findings indicate that the RPF values vary across different cycles but remain within safe limits. Specifically, the RPFs for the initial, first transition, second transition, and equilibrium cycles are 1.36, 1.21, and 1.23; 1.43, 1.38, and 1.30; 1.64, 1.44, and 1.31; and 1.29, 1.33, and 1.66, respectively, measured at the beginning, middle, and end of each cycle. These results underscore the effectiveness of the proposed fuel management strategies in maintaining a stable and safe power distribution within the reactor core. This study also underscores the potential benefits of ATF cladding materials, such as chromium-coated zirconium, which offer enhanced resistance to high-temperature oxidation, thereby improving reactor safety under normal and accident conditions. The implementation of ATFs could lead to significant improvements in safety margins, operational efficiency, and overall reactor performance. This research contributes valuable insights into optimizing in-core fuel management practices for the APR-1400 reactor. This study lays a foundation for future studies and practical applications that could further enhance the safety and efficiency of nuclear power plants. By demonstrating the advantages of ATFs and effective fuel management, this study supports the continued development and deployment of advanced nuclear technologies, promoting greater public confidence in nuclear energy as a reliable and safe power source.

Integrating machine learning and parametric design for energy-efficient building cladding systems in arid climates: Sport hall in Kerman

Climate change, driven by fossil fuel dependence, presents a significant challenge for the construction industry, particularly in energy-intensive regions like arid climates. This research investigates the potential of integrating machine learning and parametric optimization to enhance the energy efficiency of spatial structure domes in such environments. Focusing on a sports pavilion in Kerman, Iran, the study examines the crucial role of cladding systems in building energy performance. Employing a rigorous four-phase methodology, the research optimizes dome cladding materials for hot, dry climates using a dual objective function: energy cost and material cost. The process involves a comprehensive literature review, data-driven material selection, advanced energy simulations, and optimization analysis. Parametric modeling tools (Rhino, Grasshopper, Honeybee) facilitate the comparative analysis of various cladding systems. Multivariate Polynomial Regression (MPR) enables predictive modeling of energy consumption and material costs, streamlining the design process for architects. The optimized solution is a hybrid cladding model composed of 10 % polycarbonate and 90 % aluminum. Analysis reveals that the hybrid system offers superior energy optimization compared to pure aluminum (4.58 %) and polycarbonate (5.70 %). While polycarbonate has a lower initial material cost, the hybrid system achieves a balance between material expenditure and long-term energy efficiency. This highlights the importance of considering life-cycle costs when evaluating building envelope materials. This research advances a framework that leverages machine learning and parametric design for building envelope optimization. This framework empowers architects and engineers to create energy-efficient structures within arid environments, promoting a more sustainable built environment.

An efficient method for evaluating the wind resistance performance of high-vertical standing seam metal cladding systems

Uplift wind-induced responses and failure criteria of high-vertical standing seam metal cladding systems (SSMCSs) are of paramount importance for evaluating their wind resistance performance. This paper proposes an efficient evaluation method that combines a highly efficient finite element (FE) model for structural response analysis with reasonable failure criteria, based on experimental and numerical investigation. The FE model incorporating the developed equivalent spring model is established with the calibrated stiffness from tensile tests and validated through the wind uplift resistance experiments conducted on large-scale prototype structures. The recorded structural responses from the experiments validate the feasibility of the FE model in simulating the geometric and material nonlinearities of the systems. To evaluate the wind resistance performance, the failure criteria are developed based on the observed pullout mechanisms and failure modes from the experiments. These criteria take the relative deformation of standing webs and the pullout resistance strength of seam connections as critical parameters, and the relationship between them is calibrated through a series of tensile tests using a self-designed fixture. Tensile test results show notable variability in the pullout resistance strength of seam connections, with a mean value decreasing as the relative rotational angle of the standing webs increases. According to the developed failure criteria, the ultimate uplift pressures evaluated from the FE analysis exhibit minimal positive deviations of 5.3 % and 7.3 % from the experimental results for different failure modes, respectively. This highlights the effectiveness of the proposed method in evaluating the wind resistance performance of high-vertical SSMCSs.

Numerical modelling and design of cold-formed steel battens subject to pull-out failures under bushfire conditions

Thin and high strength cold-formed steel (CFS) battens and claddings serve as non-combustible elements in roof and wall cladding systems, aligning with the recommendations of Australian bushfire standards. However, they are susceptible to significant damage from heat and strong winds experienced during bushfire events, particularly in the form of batten pull-out failures. Such failures may occur at the screw connections between cladding and battens, or battens and trusses/rafters. However, pull-out failures often occur in the thinner CFS battens, when the screw fastener pulls out of the batten’s top flange, leading to the loss of entire cladding and compromising the integrity of the building envelope. This study used finite element modelling of a range of CFS batten configurations to investigate their pull-out failures under combined wind action and bushfire conditions. Finite element models were developed to simulate the pull-out failures at elevated temperatures, validated using experimental results and used in a parametric study to investigate the effects of relevant parameters. Using the results, this study has proposed suitable design equations for predicting the pull-out capacities of CFS battens at elevated temperatures. Engineers can use them to design bushfire safe CFS cladding systems.

A framework for design wind loads on air-permeable multilayer cladding systems

Air-permeable multilayer cladding (vinyl siding, roof pavers, discontinuous metal roofing, solar panels, etc.) are one of the most common types of building components in North America. Their defining aerodynamic feature is that they have an air cavity separating the component from the sheathing, studs, or interior layer. Due to air-permeability, external wind loads can transfer into the air cavity between the layers. Although these cladding systems have similar geometries in many ways, design loads are not generally available for such systems. This study aims to synthesize the available literature on the pressure equalization factor, which is the proportion of external load acting on the cladding and provide a framework for design wind loads on air-permeable multilayer cladding systems. To accomplish this, the many factors that affect the pressure equalization factor, such as the gap-to-cavity-depth ratio, panel size, and exposure are discussed. Then, the pressure equalization factors from multiple studies are combined to examine the effect of effective area on the pressure equalization factor. Finally, recommendations for implementing these guidelines into design standards are provided.

Numerical studies of pull-through failures in cold-formed steel battens at sub-zero temperatures

Cold-formed steel (CFS) roof and wall cladding systems comprising thin, high strength steel battens and claddings are popularly used in the building industry worldwide. These cladding systems have been observed to encounter failures under combined snow and strong wind actions during blizzards. Significant damage is caused by the disengagement of the entire roof/wall cladding when localised pull-through failures occur in thin-walled steel battens at the batten to truss/rafter screw connections due to a splitting mechanism around the screw head. This study uses detailed finite element analyses of the pull-through failures of a range of batten configurations under combined wind and sub-zero temperature conditions. Suitable finite element models capable of simulating the pull-through failures of battens were developed and validated using experimental results, followed by detailed numerical parametric studies. The main outcomes of this study are accurate design equations and capacity reduction factors essential for predicting the pull-through capacities of CFS battens at sub-zero temperatures.

A combined theoretical, computational, and experimental investigation to evaluate performance of suitable thermocouple for microwave processing

Accurate temperature measurement during any microwave processing of material is a contentious issue. While thermocouples are routinely utilized in conventional heat furnaces, their presence in microwave cavities may cause complications such as localized distortion of electromagnetic field, heat dissipation, thermal instabilities, microwave breakdown, and significant inaccuracies in temperature measurement. Therefore, in the present investigation thermocouple effects are discussed by providing the results of temperature estimation by various thermocouples for microwave cladding systems. The present study theoretically and experimentally explored the impact of multiple thermocouples on temperature measurements during microwave heating. COMSOL simulation models were developed to explore microwave and thermocouple interaction during microwave heating. Simulation models were used to assess the effects of the microwave power intensity, thermocouple orientation, and geometry on temperature measurement. The investigation outcomes can be utilized as a guide for selecting appropriate thermocouples in the applications of microwave cladding and other microwave-based manufacturing processes.

The development process of a candidate screening test for cladding products

AbstractThe ongoing cladding crisis within the United Kingdom has elevated the need for designers and risk assessors to have the knowledge and tools to evaluate the fire safety of proposed and existing cladding systems. This paper documents efforts to develop a test that could be used to evaluate the fire safety hazards of cladding products that were either proposed for use in design or that were found on existing buildings. Specifically, the products of interest were composite products (i.e., those comprised of multiple layers). The conceptual approach of the European harmonised system was used as a basis for investigating whether a small‐scale test could be used to evaluate product fire hazards. A relevant fire scenario was identified, this was linked to candidate large‐scale reference tests, and this was linked to performance in a candidate small‐scale test. The candidate test showed remarkable agreement with the reference large‐scale test, however, many issues were also identified. It was found that, even when specifically intended to accommodate composite products, the small‐scale test was unable to always evaluate hazards. Thus the authors were left with the conclusion—regardless of the testing system, there are always products that will not fit the testing system, however hard one tries.

An equivalent spring model for seam-clip connections of high-vertical standing seam metal cladding systems

The mechanical behavior of the seam-clip connections plays a pivotal role in the effective wind resistance design of the extensively used high vertical standing seam metal cladding system (SSMCS). An equivalent spring model is developed to represent the mechanical behavior of these connections to simplify the contact problems in the general finite element model, which is time-consuming due to the highly nonlinear contact boundary conditions. The developed model is composed of continuous horizontal and rotational springs as well as dispersed vertical rigid connections. A series of tensile experiments are first conducted to investigate the mechanical behavior of seam-clip connections to calibrate the spring parameters in the developed model. Subsequently, the equivalent spring model is validated by the structural response of a double-span sheet module (DSSM) using experimental investigation and finite element analyses. It is found that the shell finite element model incorporating the developed equivalent spring model can achieve an acceptable structural response while remarkably reducing memory requirements and computational time to about 0.3 % and 0.4 ‰, correspondingly, compared to the contact boundary condition analysis. It highlights the advancement in evaluating the structural response of high-vertical SSMCS in practical engineering applications using this developed model. Furthermore, the developed equivalent spring model has proved to be effective in predicting wind-induced seam-clip pullout failures according to the established failure criteria derived from the structural response of the system.

Hygrothermal performance of natural building materials: Simulations and field monitoring of a case study home made of wood fiber insulation and clay

This contribution presents temperature and relative humidity data monitored over nearly two years for a case study building made of natural building materials. The case study building is a single-family house located in Denmark made of wood fiber insulation, wood fiber boards and indoor clay plaster without any membranes. Three different types of cladding systems have been tested: 1) mineral plaster rendering; 2) wood cladding applied directly over wood fiberboards; 3) wood cladding with a ventilated cavity. Monitored data is provided and compared with simulations performed with a commercial hygrothermal software. The moisture content and mold growth index are calculated from monitored data. The data indicates that the hygrothermal performance of the roof is excellent (RH < 70%); the hygrothermal performance of the walls with the three different cladding systems is good; one out of two sensor groups in the floor exhibits a moisture content up to 18% at the cold side of the insulation during summer and fall. Securing sufficient and evenly distributed crawlspace ventilation is recommended for eliminating concerns of eventual mold growth. Measurements show that materials employed in this house respond quickly to moisture changes, more quickly that simulated data. This work highlights the need for validating and adjusting WUFI simulation results with measured data to provide reliable results for building envelopes composed of highly hygroscopic plant-based materials. For these assemblies in these conditions, including a vapor retarder is not needed for achieving a satisfactory hygrothermal behavior.

Pull-out failure capacities of cold-formed steel batten screw connections at sub-zero temperatures

Cold-formed steel (CFS) roof and wall cladding systems are used worldwide, and are constructed using high-strength, thin steel battens and claddings. In North American countries, which are frequently subjected to blizzards (winter storms), these cladding systems are particularly vulnerable to pull-out failures during combined windstorm and snowy conditions. Despite extensive research studies investigating the pull-out failure mechanism and the critical parameters of screw connections between cladding and battens at ambient temperature, the behaviour of these connections under blizzard conditions has not been experimentally investigated. To fill this knowledge gap, an experimental study was undertaken that included 144 laboratory tests of screw connections in battens of varying grades and thicknesses, and three distinct types of screws. The pull-out failure capacities of screw connections in battens were evaluated under wind suction loading at four different temperatures, including ambient and sub-zero temperatures. The results of the study provided insights into the pull-out failure mechanisms of screw connections in battens and enabled the development of suitable design rules for combined wind action and sub-zero temperature conditions. The findings of this study are expected to be of significant value to engineers and building designers who are involved in the construction of lightweight cold-formed steel buildings.

Leveraging machine learning for predicting and monitoring clogging in laser cladding processes: An exploration of neural sensors

This study addresses the development of smart neural sensors to predict the powder mass flow and track clogging in real time during laser cladding. The challenges posed by powder granulometry and challenging environmental conditions that can lead to delivery failures are considered. An extensive experimental setup was conducted that included manipulation of key factors, such as laser power, travel speed, Z-step, N-layers, nozzle-to-substrate distance, and two types of process patterns. The mass flow rate of the powder was used as an independent variable to evaluate the predictive ability of the neural sensor with respect to the mass flow rate. Several models were trained and evaluated with different datasets and images of the cladding equipment. The model that integrated all data and images showed the best accuracy and precision also showed a strong predictive power for real-time estimation of the powder mass flow rate. Considering two practical rules—an error detection time of no more than one second and a confidence interval of less than 1.8 g/min—two strategies were proposed to meet these criteria. The first recommends the use of the comprehensive “all-features” model, while the second proposes a simplified model (with Z-step, N-slices, and the external camera as inputs) for efficient real-time error detection. The study provides an understanding of powder clogging prediction in laser cladding and suggests strategies for leaders in the field. Future research should validate these results and test these models in different environments to predict complex cladding properties and support the development of stand-alone laser cladding systems.

Localised pull-through failures of cold-formed steel batten screw connections under combined wind and sub-zero temperature conditions

The utilisation of thin cold-formed steel (CFS) elements is widespread in contemporary lightweight building construction. Roof and wall cladding systems are predominantly made of thin, high-strength steel claddings and battens. Blizzards are predominantly observed in North American countries, resulting in significant roof damage. A localized pull-through failure mechanism, occurring at the batten to rafter/truss screw connections, has been extensively investigated at ambient temperature to comprehend the critical factors that influence the pull-through failure capacities of CFS battens. Nonetheless, the pull-through capacity of CFS battens at sub-zero temperatures has not been examined, and as a result, the performance of the steel cladding systems during blizzards under the combined action of strong winds and sub-zero temperatures remains unknown. To investigate the pull-through failure behaviour and capacities of batten screw connections, an experimental study comprising 96 tests was conducted involving two steel grades and three thicknesses of steel battens and two screw fasteners at sub-zero temperatures. The study was conducted at both ambient and sub-zero temperatures to understand the pull-through failure behaviour and capacities of batten screw connections. Appropriate pull-through capacity equations and associated increment factors were developed to predict the pull-through capacities of batten screw connections that are subjected to the combined effects of high wind uplift loads and sub-zero temperatures.

Comparison of wind-resistant capacities of standing seam roof systems under static uniform pressures and dynamic non-uniform wind pressures

Static uniform pressure tests are widely recommended to determine the ultimate capacities of standing seam roof systems in many building standards and guidelines, but such ultimate wind-resistant capacities are usually much different from those under dynamic non-uniform wind pressures. Through the comparison of the ultimate capacities of standing seam roof systems under static uniform pressures and dynamic non-uniform wind pressures by finite element simulations, the definition and calculation steps of influence coefficients of dynamic non-uniform wind pressure distribution (ICDNWPD) are proposed to reflect the effects of actual wind pressure distributions on wind-resistant capacities of the roof cladding systems. The effects of roof zones, support spacings, and terrain categories on the ICDNWPDs of flat roofs are investigated. The results show that the ICDNWPDs of the edge and interior regions are approximately 1.27–1.42 times those of the corner zones, and the ICDNWPDs are more sensitive to the roof zone than the support spacings and terrain categories. The factors of safety of roof systems with larger spans or under smoother terrain or located in the roof corner zone should be greater, which cannot remain constant.

Structure cladding interaction in sandwich panel roofs

A few years ago, several failures in the sandwich panel cladding systems of large warehouses or distribution centres (“Big Sheds”) in the UK highlighted shortcomings in the current design philosophy, which ignores the global effect of cladding on the performance of the structure. The current European Standard for including the effect of cladding (i.e., diaphragm action) in the structural analysis is inappropriate for modern cladding systems, especially in association with ultra large portal frame structures.In this paper, a new state-of-the-art for sandwich panels acting as a diaphragm to resist in-plane forces in portal frame structures is defined. The modern terminology for such interactive behaviour is now given the more general title of “Structure Cladding Interaction”. Potential cladding failure modes are highlighted and where possible quantified. The “component method” is advocated as the best way to include the global effects of sandwich panels in a 3D finite element model of the complete structure. Guidance on generating such models, obtaining the critical component properties and validation is provided, together with three detailed validation examples. The method is both scalable and general; it may be used to model the effects of cladding in any size of structure or of any structural form. It is strongly recommended that the influence of the cladding should be included in the design of any large portal frame structure. In such buildings the serviceability limit state is likely to be defined by cladding failures which may occur below the working loads. Detailed outcomes obtained using sophisticated 3D models will be presented in subsequent papers.

Microscale failure analysis of the ultra-high-performance polypropylene fibre reinforced concrete panel subjected to high thermal loading induced by fire exposure

To date, many buildings are prone to fire from non-structure systems like high-pressure laminates and insulated cladding systems. Ultra-high-performance concrete (UHPC) has been applied to the cladding systems due to its excellent mechanical properties at room temperature and non-flammable characteristic. To improve its mechanical properties under fire condition, different fibres like PP fibre have been employed to reinforce UHPC. The tensile strengths of these ultra-high-performance PP fibre reinforced concrete (UHPPFRC) panels vary due to the different orientations of internal PP fibres. However, few studies have been carried out on the internal stress and fire resistance of these claddings. Study on understanding the fire behaviours and failure process of the UHPPFRC panel is essential for developing claddings with better fire resistance and durability. In this study, a coupled hygro-thermal–mechanical model is developed to predict the internal stress and temperature distribution within the UHPPFRC panel. The microscopic failure process of PP fibre and porosity change within the panel during heating are all embodied in the model, and its accuracy has been validated. The initial and the residual tensile strengths of the UHPPFRC panel are considered to fluctuate between two extrema due to the random fiber orientation. Based on this, Program Evaluation and Review Technique (PERT) is applied to investigate the effects of fibre dosage and heating rate on retarding crack propagation and failure of the UHPPFRC panel under high temperature. Results from the numerical investigation indicate that 0.55% dosage of PP fibre can effectively postpone crack occurrence and propagation within the UHPPFRC panel at linear elastic phase, and faster heating rate can accelerate the pore pressure generation process. Also, internal fibre orientation is a significant factor affecting the fire endurance of the UHPPFRC panel subjected to elevated temperature, which should be considered for safety and reliability evaluation of the structure.

A Fire Evacuation and Control System in Smart Buildings Based on the Internet of Things and a Hybrid Intelligent Algorithm

Concerns about fire risk reduction and rescue tactics have been raised in light of recent incidents involving flammable cladding systems and fast fire spread in high-rise buildings worldwide. Thus, governments, engineers, and building designers should prioritize fire safety. During a fire event, an emergency evacuation system is indispensable in large buildings, which guides evacuees to exit gates as fast as possible by dynamic and safe routes. Evacuation plans should evaluate whether paths inside the structures are appropriate for evacuations, considering the building’s electric power, electric controls, energy usage, and fire/smoke protection. On the other hand, the Internet of Things (IoT) is emerging as a catalyst for creating and optimizing the supply and consumption of intelligent services to achieve an efficient system. Smart buildings use IoT sensors for monitoring indoor environmental parameters, such as temperature, humidity, luminosity, and air quality. This research proposes a new way for a smart building fire evacuation and control system based on the IoT to direct individuals along an evacuation route during fire incidents efficiently. This research utilizes a hybrid nature-inspired optimization approach, Emperor Penguin Colony, and Particle Swarm Optimization (EPC-PSO). The EPC algorithm is regulated by the penguins’ body heat radiation and spiral-like movement inside their colony. The behavior of emperor penguins improves the PSO algorithm for sooner convergences. The method also uses a particle idea of PSO to update the penguins’ positions. Experimental results showed that the proposed method was executed accurately and effectively by cost, energy consumption, and execution time-related challenges to ensure minimum life and resource causalities. The method has decreased the execution time and cost by 10.41% and 25% compared to other algorithms. Moreover, to achieve a sustainable system, the proposed method has decreased energy consumption by 11.90% compared to other algorithms.

Influence of Closure External Panels Modelling on the Seismic Response of Non-Residential Precast Buildings

ABSTRACT Following recent earthquakes, precast buildings exhibited a strong seismic vulnerability related to the presence of closure external panels. The aim of this work is to simulate the seismic response of existing single-storey precast buildings in the case of explicit modelling of external panels. The considered case studies are precast buildings representative of the Italian building stock in the 1970s and 1990s, characterised by two different cladding systems, namely, masonry infills and reinforced concrete precast panels, respectively. The explicit modelling of infills and panels, typically introduced solely as participating masses, provided insights into their actual contribution on the global structural behavior.

Ultra-High-Performance Concrete (UHPC) - Applications Worldwide: A State-of-the-Art Review

Research is in progress on the applications of ultra-high performance concrete (UHPC) as a new additive material in construction technology. Over the last twenty years’ significant improvements have been achieved in mechanical properties of UHPC, such as its strength, workability, and ductility, with further improvements made in self-placing properties, higher density, and durability compared with normal concrete. One of the biggest advantages offered by ultra-high performance concrete over normal concrete is the possibility to minimize the cross-sectional dimensions of the structural elements. UHPC can be used to provide significant long-span members, whilst also showing less variation, creep, and drying shrinkage compared to conventional concrete. After many years of development and research into UHPC’s properties, it is being used in commercial applications to meet the rising demand for quality constructions. Many projects in the world started using UHPC for different construction objectives such as long spans, columns, jacketing, rain-screen cladding systems, panel systems, façades, etc. Furthermore, there are not enough sources in the literature describing mixture design, preparation, and curing. This research gives an overview of the uses of UHPC in structural and architectural applications.