Search Results (30)

Lateral buckling is the governing failure mode affecting the strength of cold-formed steel purlins. In industrial roofing systems, these purlins are frequently restrained by two or three anti-sag bars within their spans. Previous research by the authors indicated that under wind suction, the buckling behaviour of purlins with multiple anti-sag bars differs significantly from those with fewer restraints, primarily due to the semi-rigid nature of the bracing. This paper investigates the lateral buckling of C-section purlins with two or three anti-sag bars, explicitly accounting for lateral restraints provided by both the roof sheeting and the bars. Simplified analytical solutions are derived to facilitate practical design. Notably, a novel parameter is introduced to identify the controlling buckling mode, which significantly simplifies the calculation procedure. The proposed solutions show excellent agreement with results obtained from both commercial and custom-developed finite element codes. Full article

Hakka traditional vernacular dwellings embody regionally specific climatic adaptation strategies. This study takes the Meizhou Guangludi enclosed house as a case study to evaluate its climate adaptability with longevity and passive survivability factors of the Hakka three-hall enclosed house under subtropical climatic conditions. A mixed research method is employed, integrating visualized parametric modeling analysis and on-site measurement comparisons to quantify wind, temperature, solar radiation/illuminance, and humidity, along with human comfort zone limits and building environment. The results reveal that nature erosion in the Guangludi enclosed house is the most pronounced during winter and spring, particularly on exterior walls below 2.8 m. Key issues include bulging, spalling, molding, and fractured purlins caused by wind-driven rain, exacerbated by low wind speeds and limited solar exposure, especially at test spots like the E8–E10 and N1–N16 southeast and southern walls below 1.5 m. Fungal growth and plant intrusion are severe where surrounding trees and fengshui forests restrict wind flow and lighting. In terms of passive survivability, the Guangludi enclosed house has strong thermal insulation and buffering, aided by the Huatai mound; however, humidity and day illuminance deficiencies persist in the interstitial spaces between lateral rooms and the central hall. To address these issues, this study proposes strategies such as adding ventilation shafts and flexible partitions, optimizing patio dimensions and window-to-wall ratios, retaining the spatial layout and Fengshui pond to enhance wind airflow, and reinforcing the identified easily eroded spots with waterproofing, antimicrobial coatings, and extended eaves. Through parametric simulation and empirical validation, this study presents a climate-responsive retrofit framework that supports the sustainability and conservation of the subtropical Hakka enclosed house. Full article

The photovoltaic industry plays a critical role in promoting global sustainability. Enhancing the reliability of photovoltaic structures is essential for achieving sustainable development. This study involved the analysis of a photovoltaic power generation project in Hubei Province to compare differences in the structural loads of photovoltaic supports as outlined in Chinese, American, and European codes. Additionally, the ABAQUS numerical simulation was used to investigate the mechanical characteristics of photovoltaic support joint connections and analyze the causes of structural deformation. Innovative joint connections were proposed to optimize the structural performance of photovoltaic supports. The results showed that photovoltaic supports designed using Chinese codes exhibit lower reliability compared to those designed using American and European codes. Specifically, at least three bolts should be installed at the purlin hanger to connect the purlin and the beam. Z-shaped and Π-shaped purlin hangers are recommended for connecting beams and purlins, as they reduce joint deformation while preventing excessive stress in L-shaped purlin hangers. C-shaped steel is suggested for braces, offering both ease of construction and structural reliability. The proposed connection design minimizes additional steel consumption while enhancing overall performance. Full article

A swimming pool in Corrales de Buelna (Cantabria) was demolished in March 2017 due to the loss of mechanical performance of the laminated timber structure. The relevant deterioration was caused by rotting of the wood and corrosion of the metal connecting elements. The structure featured a barrel vault with five large tri-articulated arches enclosed on the sides by inclined facades formed by toral rafters and purlins. The corresponding diagnostic process involved data collection and structural assessments to verify the structure’s bearing capacity and serviceability. Data collection was carried out in December 2015 and consisted of a thermal camera inspection to determine the points of moisture accumulation and sampling openings, conduct environmental and wood hygrothermal measurements, and measure cross-sectional losses and deformations of the structural elements. Verification of the load-bearing capacity was carried out using matrix calculation structure software for both the original and deteriorated structure. The diagnosis indicated that the damage was caused by leaks in the joints of the aluminum composite roof panels and by the insufficient load-bearing capacity of the structure. The severity of the damage compromised the mechanical strength and stability of the building, leading to a recommendation that the use of the facilities be immediately discontinued. The degree of deterioration left the structure unrecoverable, making it very difficult to apply reinforcement measures. These factors led to the structure’s demolition to prevent its collapse. Full article

Thin-walled channel beams such as cold-formed steel purlins are primarily used to withstand wind forces in the roofing and walling systems of buildings. Traditionally, these types of members are usually designed for bending moments, with the effects of torsion ignored. However, the loading on thin-walled channels can be much more complicated than simple bending actions. Because of the position of the shear centre outside the section, channels can undergo bending and torsion when subjected to vertical load on the top flange. The applied torsion may cause significant stresses in the channel, which may need to be accounted for in design. There appears to be no research on quantifying the effects of torsion on thin-walled channels subjected to a uniformly distributed load acting on the top flange. In this paper, a theoretical solution is derived for calculating the longitudinal stresses in thin-walled channels subjected to torsion caused by a uniformly distributed load acting on the top flange. The theory is validated by modelling the channels in a finite-element analysis. The theoretical results include calculations of the twist rotation, bimoment, sectorial coordinate and longitudinal stresses, while the results from the finite-element analysis include the twist rotation and longitudinal stresses. The results show that the longitudinal stresses caused by torsion can significantly exceed those caused by the bending moment. Practical advice is also given for engineers on how to minimize torsion in cold-formed steel purlins. Full article

High thin-walled cold-formed steel purlins of the Z cross section are important elements of large-span steel structures in the construction industry. The present numerical study uses the finite element method to analyse the 300 mm and 350 mm high Z cross sections in-depth. The prepared numerical models are verified and validated at several levels with experiments that have been previously published. Significant agreement between the numerical models and the experimental results regarding Mises stress, proportional strain, failure mode, and force-deformation diagram have been obtained. With the verification, the presented procedure and partial findings can be applied to other similar problems. The results can be used to help research and corporate groups optimise the structural design of cold-formed thin-walled steel structures. Full article

Erdene Zuu is the oldest extant Buddhist temple in the country of Mongolia, founded following the reintroduction of Tibetan Buddhism to Inner Mongolia in the sixteenth century. The subject of this paper is the building activities of the sixteenth and seventeenth centuries, particularly of the complex centering on Gurban Zuu (Three Temples), which are the main buildings of Erdene Zuu. The author first confirms Gurban Zuu’s ground plan based on measurements, and then interprets the “black-ink inscription” discovered on the ridge purlin of the Central Buddha Hall. This complex is then compared with Inner Mongolian Buddhist temples of the same period. Finally, the author studies whether or not the spatial structure of the temple architecture of the Mongolian Empire of the thirteenth and fourteenth centuries was continued at Erdene Zuu, and analyzes the position that Erdene Zuu occupied in the Tibetan Buddhist sphere. This comparative study investigates the origins of Erdene Zuu’s architectural spatial composition within East Asia. Full article

This study demonstrates the design and field implementation of an innovative servo concrete bracing system in foundation pit excavation. The bracing system comprises concrete struts, revised purlins, and hydraulic jacks, and its field performance is evaluated in a deep foundation pit project in Shanghai, China. The field measurements demonstrate that the servo bracing system effectively reduces the maximum lateral displacement of the retaining wall by up to 31%. Moreover, the servo jacks modify the wall’s flexural behavior by introducing local inflection points at certain depths and driving the displacement peak upward. Furthermore, the system’s performance varies with strut configuration, and servo forces influence not only the corresponding acting strut but also the adjacent struts’ behavior, implying that the monitoring scope should be expanded when applying the servo bracing system in actual engineering. This study provides a meaningful technical reference for future servo concrete bracing system applications in foundation pit engineering. Full article

The construction industry has a notably negative impact on the environment; thus, the promotion of the use of timber structures is an alternative to mitigate its effects. This research develops an artificial intelligence-based decision approach in the calculation of timber structures focused on the enhancement of the sustainability of roof structures. Based on the optimization carried out through genetic algorithms and the framework established in Eurocode 5, a general set of equations has been proposed for a laminated timber roof structure. The tool, which determines the most suitable roof structure for each strength class of laminated timber, allows for the determination of the dimensions of beams and purlins and their respective separations in order to minimize wood consumption. The ultimate goal is to offer multiple solutions regarding strength classes and structural designs in order to foster sustainability-informed choices that promote efficient use of resources in construction. Full article

This study takes the wooden components of the different parts of the ancient buildings at the site of the Zhuangzishang Conference as the object of study, and investigates the deterioration state of the different wood components. To assess their degree of degradation, the wood anatomy, basic density (BD), maximum water content (MWC), cell wall major components, X-ray diffraction (XRD), infrared spectroscopy (IR), and thermogravimetry (TG) were used to compare the samples of new and old wood from the same species. The window (W) was identified by microscopic characterization as cypress (Cupressus sp.), the footing beam (FB) and the weatherboard (WB) as pine (Pinus spp.), the purlin (P) and the column (C) as Chinses fir (Cunninghamia spp.), and the floor (F) as spruce (Picea sp.). In terms of their physical properties, the old wood had a lower basic density of 2.58%–38.19%, a lower air-dry density of 2.87%–39.81%, and a higher maximum moisture content of 8.52%–41.38% compared to the reference wood. The degradation of the FB, which has been subjected to moisture and sunlight, and the P, which has been subjected to termite damage, was greater than that of their conspecifics. The integrated holocellulose of the ancient wood was 3.34%–16.48% less, and the hemicellulose was 1.6%–21.92% less compared to that of the reference wood, and the lignin was 1.32%–25.07% more. The XRD results showed that the crystallinity of the cellulose was greater in the different species of ancient wood compared to the control wood, which was caused by the decrease in the amorphous zones of the hemicellulose and cellulose in the ancient wood. The IR indicated that the degradation of cellulose and hemicellulose occurred in the old wood of all species, from the new lignin uptake peaks in the UV-exposed W, FB, and WB compared to the control timber. The pyrolytic behavior of the ancient and control timber is mainly related to the degradation of the tree species and the ancient wood holocellulose. These results show that the differences in the wooden components of the different parts of the ancient buildings at the Zhuangzishang Conference site are mainly related to the species of trees used in the components, and are secondly related to the location of the ancient wood members, which provides useful information for the protection and repair of the ancient buildings at the site. Full article

Previous research has agreed that standard modular methods in Song Yingzao Fashi and Qing Gongcheng Zuofa were not applied to Korean wooden architecture. This study notes the size of bracket arms as a standard modular method by investigating the proportion systems of Sungnyemun, Paldalmun, and Heunginjimun Gates, the official government buildings of the Joseon Dynasty. The purlin direction bracket arms in the intercolumnar bracket sets apply a proportional system in the ratio of a regular integer relationship to the front and side facades and building height. Challenging current assumptions, the application of the bracket arm width as a modular rule is divided into more subdivided values than the measurement units. A particularly important finding is that, unlike the height of the bracket arms, the width and length of the brackets are standard members that determine the height of the side facades. This is very similar to the official government building styles in the Song and Qing Dynasties, premodern China. Therefore, this study is meaningful in reassessing wooden frame structures of the Joseon era, deriving parametric measuring rules universally applied in East Asia to provide basic data useful for heritage conservation. Full article

Exact interaction formulae for the plastic resistances of Z-sections under a combination of three internal forces, i.e., the bending moment about the strong axis M_y,Ed, bending moment about the weak axis M_z,Ed and bimoment B_Ed, were created and analyzed. The exact interaction curves obtained by linear programming have enabled us to create and verify the proposed approximate interaction formulae. An interaction formula that takes into account these three internal forces is missing in the Eurocodes. A large parametric study was performed for rolled Z profiles. The differences between the values of the approximate interaction formulae and exact interaction curves were analyzed and summarized. The importance of correct analyses of Z-sections in Part 3 is described and examples of incorrect calculations in many publications are collected and corrected. Several researchers have analyzed plastic resistances of I-, H-, T- and U-sections under the combination of internal forces, but nobody has studied Z-sections which are frequently used as purlins. Another motivation is to show how to calculate the properties and normal stresses in the sections without axes of symmetry, which are frequently calculated in incorrect ways, when using non-principal axes of the section. Full article

This paper addresses the lack of attention paid by the scientific community to the optimization of timber structures, specifically in the context of large-span agro-industrial constructions. The study focuses on the optimization of a three-dimensional roof composed of GL32h glulam regular double-tapered beams and purlins. Firstly, MATLAB was employed to develop a calculation software and then run the proposed optimization model based on genetic algorithms, in order to optimize the different geometries of the construction elements based on cost, as well as the optimum arrangement of the purlins and the number of beams. Moreover, statistical analyses were carried out on more than 200 optimization data points to uncover the influence of different variables in the optimization process. It was found that the snow load and span have a significant influence on the prediction of the height and width of beams and purlins, as well as the purlin spacing; while, as expected, the roof length also influences the optimal number of beams. All these findings could promote the use of timber structures; thus, achieving more sustainable and efficient construction practices. Full article

This study investigated the structural behavior of a beam–slab member fabricated using a steel C-Purlins beam carrying a profile steel sheet slab covered by a dry board sheet filled with recycled aggregate concrete, called a CBPDS member. This concept was developed to reduce the cost and self-weight of the composite beam–slab system; it replaces the hot-rolled steel I-beam with a steel C-Purlins section, which is easier to fabricate and weighs less. For this purpose, six full-scale CBPDS specimens were tested under four-point static bending. This study investigated the effect of using double C-Purlins beams face-to-face as connected or separated sections and the effect of using concrete material that contains different recycled aggregates to replace raw aggregates. Test results confirmed that using double C-Purlins beams with a face-to-face configuration achieved better concrete confinement behavior than a separate configuration did; specifically, a higher bending capacity and ductility index by about +10.7% and +15.7%, respectively. Generally, the overall bending behavior of the tested specimens was not significantly affected when the infill concrete’s raw aggregates were replaced with 50% and 100% recycled aggregates; however, their bending capacities were reduced, at −8.0% and −11.6%, respectively, compared to the control specimen (0% recycled aggregates). Furthermore, a new theoretical model developed during this study to predict the nominal bending strength of the suggested CBPDS member showed acceptable mean value (0.970) and standard deviation (3.6%) compared with the corresponding test results. Full article

In this study, the flexural performance of a new composite beam–slab system filled with concrete material was investigated, where this system was mainly prepared from lightweight cold-formed steel sections of a beam and a deck slab for carrying heavy floor loads as another concept of a conventional composite system with a lower cost impact. For this purpose, seven samples of a profile steel sheet–dry board deck slab (PSSDB/PDS) carried by a steel cold-formed C-purlins beam (CB) were prepared and named “composite CBPDS specimen”, which were tested under a static bending load. Specifically, the effects of the profile steel sheet (PSS) direction (parallel or perpendicular to the span of the specimen) using different C-purlins configurations (double sections connected face-to-face, double separate sections, and a single section) were investigated. The research discussed the specimens’ failure modes, flexural behavior, bending capacity, bending strain relationships, and energy absorption index of specimens. Generally, the CBPDS specimens with the PSS slab placed in a parallel direction achieved approximately a 13–40% higher bending capacity compared with the corresponding specimens with a perpendicular PSS direction (depending on the configuration of the beam). Fabricating the beam of the CBPDS specimen with double C-purlins (face-to-face) led to more effective concrete confinement behavior compared with the double separate C-purlins beam. The related specimen recorded a 10% higher bending capacity. Finally, the suggested composite CBPDS system exhibited a sufficient energy absorption capability of the static bending load because it demonstrated high strength and high ductility. Full article