Among the techniques for converting stacked coal gangue to reusable material, one of the most effective ways is to use coal gangue as a coarse aggregate in green concrete productions. The physical ...and chemical properties of rock and spontaneous-combustion coal gangue are generally suitable for being used as a coarse aggregate in green concrete. Coal gangue concrete is not recommended to be used in subsurface structures, as its water absorption law would be changed under a large replacement ratio. The mechanical performance of coal gangue concrete is degraded by raising the replacement ratio. Over-low and -high concrete grades are not suggested to be used as coal gangue aggregate, unless extra admixtures or specific methods are used. The influence of coal gangue on the durability of coal gangue concrete is remarkable, resulting from the porous structure of coal gangue that provides more transmission channels for air and liquid in concrete, but is beneficial for thermal insulation. The usage of coal gangue in structural concrete members is still limited. The mechanical behavior of some structural members using coal gangue concrete has been reported. Among them, concrete filled steel tubes are a preferable configuration for using coal gangue concrete, regarding both the mechanical and durability performance.
•A mathematical model is presented for simulating circular DCFST slender columns.•Incremental nonlinear equilibrium equations are solved using Müller’s method.•Accurate material laws for sandwiched ...concrete in circular tubes are described.•The behavior of high strength circular DCFST slender columns is investigated.•The model presented is shown to be an accurate simulation tool for DCFST columns.
Circular double-skin concrete-filled steel tubular (DCFST) slender columns made of high-strength concrete are high performance structural members with wide applications in engineering structures. However, research studies on the behavior, load distributions in concrete and steel components and confinement characteristics of such composite columns under eccentric loading have been very limited. This paper describes a new mathematical model that computes the axial load-deflection performance of high-strength circular DCFST slender columns subjected to eccentric loading. The incremental nonlinear equilibrium equations of DCFST slender columns are solved by the developed efficient computational procedure and numerical solution algorithms accounting for initial geometric imperfections and second order effects. The mathematical model incorporates the accurate material constitutive laws of sandwiched concrete, which accurately predict the residual concrete strength and strain in the post-yield regime. The computer program implementing the mathematical model is utilized to quantify the influences of geometric and material properties and concrete confinements on the load-deflection behavior, column strength curves and load distributions in circular DCFST slender columns. It is shown that the mathematical model not only accurately predicts the experimental behavior of circular DCFST slender columns but also effectively monitors the load distributions in concrete and steel components of DCFST slender columns under deflection increments. The proposed mathematical model is an accurate and efficient computational and design technique for circular DCFST slender columns.
The design of modern carbon-based beam-like aircraft and spacecraft panels is complex and cost-consuming from an experimental point of view. Effective computational approaches to vibration problems ...of these structures are expected and desired to create numerical tools for their optimization and analysis, especially in the nonlinear regime of problems.
This paper presents a theoretical investigation of nonlinear responses of nanohybrid beam-based panels. The beam is manufactured from a polymer matrix reinforced by carbon nanotubes (CNTs) and graphene platelets (GPLs). The same matrix is applied for different layers to reduce inter-laminar stresses. The two well-known homogenization techniques, namely the Mori–Tanaka (MT) approach and the modified Halpin–Tsai scheme, are used to estimate the effective material properties of each nano-reinforced layer, respectively. The nonlinear governing Euler-Lagrange equations of panels are derived based on Reddy's third-order shear deformation theory (TSDT), incorporating the von Kármán strains. Effective numerical isogeometric analysis (IGA) developed by Hughes et al. is utilized to establish the nonlinear eigenvalue problem solved by the direct iterative method. Comprehensive comparison studies including FEM are performed for the developed procedure to illustrate the reliability and the correctness of the obtained IGA solution for linear and nonlinear dynamic problems. Parametric studies are conducted to examine the hybridization effect of nano-fillers, lamination angle, geometric and material properties, and vibration amplitude on the dynamic response of the structure. New insights into the linear and nonlinear vibrational response of the hybrid beam-like aerospace structures are presented and discussed.
•A comprehensive simulation model has been developed to predict the overall energy performance of PV-DSF.•Sensitivity analyses of air gap depths were conducted and the optimal air gap depth was ...identified.•The overall energy performance and energy saving potential of the PV-DSF was evaluated.•A comparative study was conducted between the PV-DSF and other commonly used window technologies.
This paper presents the annual overall energy performance and energy-saving potential of a ventilated photovoltaic double-skin facade (PV-DSF) in a cool-summer Mediterranean climate zone. A numerical simulation model based on EnergyPlus was utilized to simulate the PV-DSF overall energy performance, simultaneously taking into account thermal power and daylight. Based on numerical model, sensitivity analyses about air gap width and ventilation modes have been lead in Berkeley (California) with the aim to optimize unit’s structure design and operational strategy of PV-DSF. Via simulation, the overall energy performance including thermal, power and daylighting of the optimized PV-DSF was evaluated using the typical meteorological year (TMY) weather data. It was found that per unit area of the proposed PV-DSF was able to generate about 65kWh electricity yearly. If high efficiency cadmium telluride (CdTe) semi-transparent PV modules are adopted, the annual energy output could be even doubled. The PV-DSF studied, also featured good thermal and daylighting performances. The PV-DSF can effectively block solar radiation while still providing considerable daylighting illuminance. Due simply to excellent overall energy performance, a PV-DSF at Berkeley can reduce net electricity use by about 50% compared with other commonly used glazing systems. Efficiency improvements of semi-transparent PV modules would further increase the energy saving potential of a PV-DSF and thus making this technology more promising.
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•High-efficient buildings and NZEB need operable and adaptive building components.•Multi-objective requisites are energy-saving, use of renewables, and indoor comfort.•DSF and ...responsive components can be useful for both retrofits and new buildings.•Recent examples of applications to both new and retrofit designs are reviewed.•Experiments and numerical studies should optimize design and management.
The building sector is – directly or indirectly – the first pillar for application of technologies aimed at reducing energy wastes. To achieve sustainable growth goals, worldwide, the building stock needs to be re-developed from the energy viewpoint. This study focuses the attention on the building envelope, since it is the primary subsystem through which energy losses occur between inside and outside environments, by reviewing and discussing the most recent and cutting-edge researches in matter of double-skin and responsive façades for the building retrofit. Each study is investigated by characterizing the technology, the location (i.e., the climatic conditions) and season of analysis, the building intended use and the main findings. The objective is identifying potentialities and recurrent benefits related to the discussed retrofit solutions – such as reduction of energy consumption and CO2-equivalent emissions, exploitation of renewables, conceptual transformation of the building envelope – but also barriers and criticalities – such as overheating risk, lower efficiency of transparent photovoltaics compared to traditional ones, high cost of responsive elements – which have to be addressed and solved in the future. In this vein, a comprehensive snapshot of the evolution of building envelope retrofit solutions is provided with original insights into current and future trends with a view to low- (or zero-) energy buildings. Despite the critical aspects and barriers to overcome, the potential advantages make most of the addressed technologies an important tool to achieve the sustainable renovation of the existing building stock, and therefore their potentialities must be deeply investigated and understood.
With the global target to promote energy saving in buildings, various studies draw attention to the role of environmentally benign building envelopes. In this regard, double-skin façades (DSFs) have ...been proposed as a promising passive building technology to enhance the energy efficiency and improve the indoor thermal comfort at the same time. A comprehensive analysis of the current design of DSFs, and their technical aspects is presented in this paper. Construction characteristics of DSFs are also reported. The impacts of DSFs on the energy efficiency and thermal performance are discussed by looking at measured and simulated performances. Findings confirm that significant benefits result from using DSFs. Finally, research opportunities are outlined for further investigation.
Abstract
Double Skin Facades (DSF) are regaining popularity as a way to increase the climate resilience of buildings. Building Performance Simulation (BPS) is commonly used for their assessment, but ...modelling DSFs with BPS is challenging due to their complex thermophysical behaviour. Several research works have evaluated the capabilities and limitations of BPS for modelling specific DSF configurations. This work presents a validation study based on experimental data from a full-scale naturally ventilated double-skin façade, compared against results from the BPS software IDA-ICE. The study found that in periods with low solar irradiation, the different modelling strategies had a minor influence on the results, with a high agreement between measurements and simulation. In contrast, periods with solar irradiation showed a higher sensitivity to the modelling strategy, with more significant deviations from the measurement results.
Cold-Formed Steel (CFS) section for several decades was not considered as a structural member in building and civil engineering constructions due to inadequate technical information available about ...its usage, despite the potentials it demonstrated as proven by current research studies. Therefore, this paper aimed at demonstrating the structural capability of CFS section as a sustainable structural member in building and civil engineering constructions. Some research studies conducted reported in this paper shows the possibility of CFS section to be utilized as a structural member in the construction industries. Results from the research studies reported shows that flexural capacities were found to be increased when the CFS section was integrated compositely. In conclusion, and as demonstrated in this paper based on the studies reported, the CFS section can be employed as a sustainable structural member in small and medium size buildings, civil engineering and in lightweight industrial constructions.
This article presents the state of the knowledge on the thermal analysis of double skin facades with integrated photovoltaic (PV) panels called the Building Integrated Photovoltaics (BIPV) in terms ...of the published studies carried out on these systems. The idea of integration of the PV panels by replacing building elements, increase the prospects of the renewable energy systems. Taking also into account the need to use more renewable energy systems in buildings, the investigation of the BIPV systems to improve their performance is of a great importance. The literature studies are separated into experimental and theoretical for naturally ventilated systems and mechanically ventilated with external means e.g. fan use. It is concluded that most researchers studied the systems with mechanical ventilation rather than the systems with natural ventilation because the latter are more complex in terms of the air flow behaviour in the air duct. Additionally, various researchers proposed Nu number correlations and convective heat transfer correlation under several assumptions and conditions every time, for different range or Ra number which are presented and compared in this paper.
•Various studies investigated the heat transfer analysis of double skin facades and air flow in open ducts.•Comparison of Nu number correlations from literature and discussion of the convective heat transfer coefficients.•The optimum air gap between for a BIPV system.•The range of the Nu number in double skin facades and the expected range of heat transfer coefficients.
Blasts resulted from industrial/residential accidents and deliberate attacks can impose extremely hazardous loading conditions upon nearby structures. The repercussions of these blasts encompass not ...only direct effects such as blast overpressure and fragments but also indirect outcomes like progressive collapse of structures. In the pursuit of enhanced protection for concrete structures, substantial endeavors have been directed towards developing innovative construction materials with outstanding properties, among which the ultra-high performance concrete (UHPC) has emerged as a notable representative. Drawing from existing experimental, numerical and theoretical studies, this paper presents an inclusive overview of recent progress in UHPC structural members (slabs, beams and columns) and UHPC-based composite structures (mesh reinforced UHPC, UHPC-filled steel tube and UHPC strengthening of normal reinforced concrete (NRC) structures) in their ability to withstand blast loads. While discussing the exceptional material and structural dynamic performance of UHPC, recommendations are offered for the further research directions in utilising UHPC structures to resist blast loads, which include exploring eco-friendly UHPC, integrating 3D printing technology and employing machine learning analytical methods.
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