Search Results (84)

During the 28th Conference of the Parties (COP28), organized under the United Nations Framework Convention on Climate Change and hosted by the United Arab Emirates, member nations reached a global agreement to begin transitioning away from fossil fuel dependence, forcing the Gulf Cooperation Council (GCC) countries to balance their commitment to a green transition with the need to secure short-term energy supplies. This study highlights the challenges facing the GCC’s efforts to expand renewable energy, even as the region continues to have a significant influence over international energy markets. This study utilizes dynamic panel estimation over the period 2003 to 2022, focusing on the core pillars of the Energy Transition Index to analyze the evolving renewable energy use in the GCC. The results present a clear and optimistic perspective on the region’s renewable energy prospects. Despite the continued dependence on fossil fuels, the findings indicate that, if effectively managed, oil and gas revenues can serve as strategic instruments to support the transition toward cleaner energy sources. These insights offer policymakers robust guidance for long-term energy planning and highlight the critical importance of international collaboration in advancing the GCC’s sustainable energy transition. Full article

A novel endplate bolted rigid joint is proposed in this study for connecting circular concrete-filled steel tube (CCFT) columns to wide-flange (WF) steel beams. The seismic performance and potential failure mechanisms of the proposed joint were investigated through quasi-static cyclic tests and finite element (FE) simulations. This study aims to address several engineering challenges commonly observed in existing joint configurations, including an irrational force-resisting mechanism, complicated detailing and installation, on-site construction difficulties, constraints on beam size, and limited repairability. By optimizing the force transfer path, the new joint effectively reduces the number of critical tension welds, thereby enhancing the ductility and reliability. The experimental results indicate that the joint exhibits adequate flexural strength, stiffness, and ductility, with stable moment–rotation hysteresis loops under cyclic loading. Moreover, full restoration of the joint can be achieved by replacing only the steel beam and endplate, facilitating post-earthquake repair. FE analysis reveals that, under the ultimate bending moment at the beam end, multiple through cracks develop in the high-strength grout—which serves as a key load-transferring component—and significant debonding occurs between the grout and the surrounding steel members. However, due to confinement from adjacent components, these internal cracks do not compromise the overall strength and stiffness of the joint. This research provides an efficient and practical connection solution, along with valuable experimental insights, for the application of CCFT columns in moment-resisting frames located in high seismic zones. Full article

This study addresses the optimization of actuator arrangements in adaptive cable–strut tension structures to enhance structural controllability and performance. Two novel optimization criteria are proposed: (1) a weighted sensitivity criterion that integrates nodal displacements and internal force increments, and (2) a system strain energy criterion reflecting overall structural stiffness. Nonlinear optimization models are formulated for these criteria, with actuator positions as design variables, and solved using a robust multi-population genetic algorithm. The weighted sensitivity criterion prioritizes targeted control of specific nodes and members, while the strain energy criterion ensures balanced global response. Numerical validation is conducted on a Geiger cable dome and a four-layer tensegrity structure. Results demonstrate that both criteria yield actuator arrangements satisfying geometric symmetry while achieving high sensitivity in displacement and internal force control. The proposed framework offers practical insights for optimizing adaptive structures under static control requirements, and advances the field by bridging localized and global response optimization, enabling smarter, more resilient tension structures. Full article

Steel frame infilled with composite plate shear wall (SF-CPSW) is an effective structure for lateral-load resisting. In the structural design, the vertical loads are primarily carried by the boundary SF, while the horizontal loads are expected to be totally carried by CPSW. CPSW incorporates the steel web and the concrete encasements. For the CPSW bays, the boundary SF also inevitably withstands the lateral-loads due to the coordinated deformations between boundary SF and CPSW. The available researches, however, have not given a certain shear force assignment between the boundary SF and CPSW. Furthermore, their interactions under the cyclic lateral-loading are unclear. This paper conducted a study on the load-resisting mechanism of SF-CPSW by a structural model test and finite element analyses. The deformation pattern, failure mode, internal forces, and interactions of structural members were investigated. The effects of steel web and concrete thicknesses, cross-sections of boundary SF, and axial compression ratio on the lateral-load resistance of SF-CPSW were assessed. The results indicated that the interactions of CPSW and boundary SF caused significant normal stresses at the corners of CPSW, reducing the shear strength of steel web. However, the concrete encasements and boundary SF compensate it and mutually improved the stiffness and ductility. According to the analysis results, the formulas of the lateral stiffness and strengths of SF-CPSW were proposed for its seismic design. Full article

An important way to realize urban–rural integration and regional coordinated development is to attract labor forces back to rural areas. Most of the existing studies consider the impact of individual factors on population migration, they lack a systematic framework to analyze the combined impact of different factors on rural return migration. Furthermore, in practice, the interaction within the rural social ecosystem as an important driver of return migration is always ignored. Using data from 131 villages in 14 cities in Guangxi, China, combined with the Coupled Infrastructure System framework and the sustainable livelihoods framework, this paper analyzes the comprehensive impact of internal components of the rural social ecosystem on return migration. Qualitative comparative analysis is used to identify four condition combinations that can effectively promote return migration and five condition combinations that make return migration vulnerable. The main conclusions are as follows. First, high-level public infrastructure providers are an important driving factor for labor return to rural areas, and a substitution effect exists between them and livelihood capitals. Second, sufficient human capital and social capital are crucial for return migration, highlighting the importance of the structure of rural members and the collective atmosphere. Third, natural capital and economic capital emphasized by previous research are not key conditions for forming a high level of return migration. Fourth, the vulnerability of return migration is mainly caused by the decline of social capital, the loss of public infrastructure providers, and excessive dependence on economic or physical capital input. To attract return migration, rural areas need to pay attention to the integration and synergy of multi-dimensional capital and public infrastructure providers, and special emphasis should be placed on the cultivation of public leadership to promote the enhancement of human capital and social capital. This paper provides a more comprehensive and instrumental analytical perspective for understanding and promoting rural return migration. While deepening the understanding of the dynamic relationship between rural social ecosystem and labor mobility, it also offers policy insights for developing countries to achieve integrated urban–rural development. Full article

Split reinforced concrete column (SRCC), recognized for their exceptional ductility as seismic members, have faced developmental challenges due to the complexities of on-site casting. This study presents an innovative steel sleeve dry connection assembled SRCC, which is highly modular and simplifies construction, aiming to promote the engineering application of this innovative ductile seismic structural system. This study used a validated 3D finite element (FE) method to analyze internal joint forces. Key parameters influencing joint performance, such as the axial compression ratio (u) and cross-sectional equal division ratio (n), were analyzed in detail. Subsequently, a comparative of dynamic analysis of SRCC and normal reinforced concrete column (NRCC) frames was conducted, leading to recommendations for structural strengthening. The analysis revealed that the sleeve can provide effective protection for the core area of the joint. The ductility of SRCC is 2–3 times higher than that of NRCC. A detailed formula for calculating the shear-bearing capacity of SRCC joints was derived, showing strong agreement with numerical simulations. At a high seismic intensity of 9°, the acceleration response of the SRCC frame is significantly reduced compared to the NRCC frame, with the maximum base shear (MBS) decreasing by approximately 4 times, which significantly enhances its seismic performance. However, due to the larger inter-story displacements, it is necessary to incorporate energy-dissipating braces to comply with code requirements. Collectively, these findings underscored that the proposed SRCC system significantly enhances seismic performance by improving ductility and energy dissipation, providing a robust foundation for future studies and practical applications in seismic design. Full article

This study investigates the construction methodology of large-span cable-stayed tensioned metal thin-sheet structures, introducing the “integrated enclosure and load-bearing” design concept. By applying in-plane prestress, the out-of-plane stiffness of the metal thin sheet is effectively enhanced, enabling it to simultaneously serve as an enclosure and a load-bearing component. Through experimental studies and finite element analysis, the study systematically examines the effects of various construction methods on internal forces and displacements. The tensioning of back cables is identified as the safest and most efficient construction method. Subsequently, through simulations of a three-span structure and tensioning forming tests, the research examines displacement, stress, and cable force distribution patterns, demonstrating that increases in the tensioning level result in corresponding increases in sheet surface stress, cable forces, and displacements. The structure exhibits a concave middle section, upward curvatures at both ends, and outward-leaning end columns. Structural members with lower cable forces show minimal impact on displacement and are therefore identified as suitable targets for design optimization. This study offers a theoretical foundation and practical engineering insights to guide the optimization of design and construction for cable-stayed tensioned metal thin-sheet structures. Full article

According to conclusions agreed to in the 1995 Report of the World Summit for Social Development and the 2015 Sustainable Development Summit, seventeen sustainable development goals (SDGs) have been ratified and published as the 2030 Agenda for Sustainable Development. In 2022, the 8th Environment Action Programme was legally agreed upon, following the six European Green Deal priorities. These SDGs serve as a constant reminder of the importance of globally coordinated actions in compliance with the theory of sustainable development. However, more than a constant reminder, this international agreement should become the foundation for necessary change. On 22 July 2024, the daily global average temperature reached a new record high. The EU treaties signed between 1951 and 2007 laid the foundation for the creation of EU environmental policy. However, those EU treaties, along with environmental policy, form merely a non-binding and minimum set of priorities without any sanctions imposed for illegal practices. In 2021, EU member countries adopted the European Climate Law as the first legally binding document seeking to achieve goals set by the Paris Agreement and the European Green Deal. Any further EU sustainable development policies are dependent on global cooperation as a key element of survival. With the EU’s dependent on the rest of the world for its energy, the forcing of any obligatory change will be hard to achieve. This proves the importance of the 17th SDG, agreed in 2015. Only global partnership for sustainable development can prevent further damage to our ecosystem and achieve priorities set by the EU and UN agendas. The review aims to present the connection between sustainable development (SD) goals defined by the European Commission, for which the most important aspects are the need to meet the environmental requirements to protect future needs in the long run, and to confront the shortcomings of European law-making practices, in which most crucial reforms are presented as non-binding legal acts. Finally, in 2024 members of the European Parliament established an extended list of environmental crimes to be regarded as punishable offences and replaced the Environmental Crime Directive, making criminal activities and offences potentially legally punishable; however, it is yet to be seen how this initiative will be incorporated within the national legislations of each EU member country and to what extent. Full article

Small- and medium-sized companies depend heavily on their internal configuration to achieve their goals, generate profit, and remain competitive. The performance of the sales department is often crucial for this. Decision-makers need to understand how to coordinate the sales force’s operations while considering team members’ communication and commitment. This article presents an approach to prioritize factors that will improve the operations of the sales department in small- and medium-sized companies in the industrial sector. To achieve this, we adopted the soft modeling approach by (1) outlining a conceptual model that identifies the factors that can lead to improvements based on the literature and (2) using the analytical hierarchy process to validate a construct and prioritize the factors. This study is focused on the organizational domain and involves the participation of sixty employees from medium-sized Mexican companies with at least five years of experience. The results indicate that the factors that foster improvement in sales department operations are communication improvement, failure prevention, workload alignment, and adequate integration of human efforts with technology without neglecting coordination and management mechanisms. This article could encourage academics and practitioners to adopt the soft modeling approach to adopt new courses of action based on continuous learning and improve organizational cohesion. Full article

Although bolted joints may appear simple and are easy to manipulate, they are challenging to model and analyze due to their complex structural patterns and statically indeterminate nature. Ensuring the structural integrity of these joints requires maintaining proper bolt preload and clamping force, which is crucial for preventing failures such as overload, excessive bearing stress, fatigue, and stripping caused by seizing or galling. Achieving the necessary clamping force involves carefully controlling the input tightening torque, which is divided into the pitch torque and the friction torques at the bolt or nut bearing surfaces and in the engaged threads. The resulting clamping force is critical for generating the required force within the bolt. However, the achieved bolt force depends on several factors, such as friction at the joint’s contact surfaces, grip length, and the relative rotation between the bolt and nut during tightening. Friction at the contact surfaces, particularly beneath the bolt head or nut and between the threads, consumes a significant portion of the applied tightening torque—approximately 90%. This paper explores the three existing bolt internal pitch, bearing, and thread friction torques that are generated by the external applied torque in a bolted joint, as well as their contributions and variations throughout a loading cycle composed of three phases: tightening, settling, and untightening. An analytical model is developed to determine these torque components, and its results are compared with those obtained from finite element (FE) modeling and experimental testing from previous studies. Finally, this study examines the torque–tension relationship during bolt tightening, offering insights into the required accuracy of bolt and clamped member stiffness. The bolt samples used in this study include M12 × 1.75 and M36 × 4 hex bolts. Full article

Frequent seismic events have demonstrated that building collapse is primarily caused by the loss of load-bearing capacity in vertical structural members. In response to this risk, various national design codes have been established. This study conducted field investigations at an earthquake site in Luding County, Sichuan Province, which was struck at a magnitude of 6.8 on 5 September 2022. In this case, the lower x-direction load-bearing wall of the Tianyi Hotel suffered severe shear damage, and the building was on the verge of collapse. However, no obvious damage was seen in the elementary school dormitory. Numerical simulation analysis revealed that during the earthquake, the buildings primarily experienced y-direction displacement in the x-direction, with significant differences in the stress state among different axes. In the model of Tianyi Hotel, the x-direction load-bearing walls suffered shear damage, while the frame columns were still in the elastic stage. At this point, the shear force of the walls was 6–9 times that of the frame columns. Comparing the damage characteristics of the two buildings during the earthquake, it was found that different structural forms lead to different internal force distributions. This phenomenon is further interpreted through the principle of “deformation saturation”, with core structural components being modeled and tested using quasi-static experiments. The results indicated substantial differences in material properties among different structural forms, including variations in lateral stiffness, ultimate load-bearing capacity, and maximum displacement. Moreover, at the same floor level, components with smaller ultimate displacements are decisive of the overall structural stability. To ensure seismic resilience and stability, it is essential to consider not only the load-bearing capacity but also the rational arrangement and cooperative interactions between different components to achieve a balanced distribution of overall stiffness. This approach significantly enhances the building’s resistance to collapse. Full article

The precise calculation and effective control of the horizontal displacement of deep foundation pit retaining structures are critical for foundation pit support design and construction. Based on stress–strain linear elastomer theory and considering the deformation coordination between an enclosure wall and its internal support member, a formula for the redundant restraint force acting on the retaining wall was derived through the unit load method and the principle of elastic superposition. Moreover, a method for calculating the horizontal displacement of the retaining structure of a deep foundation pit was formulated, which is convenient for engineering applications. The method can also be used to calculate the horizontal displacement of cantilevered and anchored retaining structures when the loading conditions of the deep foundation pit and the relevant parameters of the enclosure structure are known. A case study was conducted on a standard section with an excavation width H of 19.3 m and an excavation depth h of 17.8 m. The structural parameters of the enclosure wall, along with the elastic support stiffness coefficient and soil layer parameters of the pit, were inputted into a MATLAB calculation code. Then, four internal support constraint forces F_i and the calculated values for the horizontal displacement of the enclosure wall were obtained after running the code. The calculated curve closely matched the curve of values measured in the field. The horizontal displacements of the top of the wall of several cement–soil gravity enclosure structures mentioned in the literature were also calculated. The results of these calculations were then compared with the measured data and corresponding data from the literature. The examples provided clear evidence demonstrating that the proposed method is highly reliable for calculating the horizontal displacement of deep foundation pit enclosure structures. Full article

The “321” prefabricated highway steel truss bridge is widely used for highway rescue, disaster relief, and emergency traffic. This paper uses a 33 m double-row monolayer “321” prefabricated highway steel truss bridge to analyze its mechanical properties and component stability. The actual traffic flow capacity of a total weight of 53.32 tons is used in this study. The results show that the maximum internal force in the truss chord (including the stiffening chord) occurs in the middle span section when a centrally distributed load is applied. Meanwhile, the maximum internal force of truss diagonal members and truss vertical bars appears at the fulcrum section. Under the eccentrically distributed load, the maximum internal forces of truss chords (including stiffening chords) appear in the middle span section, which is closest to the vehicle load, while the maximum internal forces of truss diagonal members and truss vertical bars appear in the fulcrum section, which is closest to the vehicle load. While the maximum internal forces under the eccentrically distributed load are greater than the maximum internal forces under the centered-layout load, under the vehicle load, truss chords (including stiffening chords) are prone to buckling instability, and the buckling mode is mainly reverse out-of-plane buckling. The inclined members of the truss are prone to buckling instability, and the buckling mode is mainly the combination of out-of-plane bending and two-way out-of-plane bending. Truss vertical bars have good stability and are not easy to buckle. The main conclusions of this paper can provide references for the optimal design and operation safety of prefabricated highway steel truss bridges. Full article

In this study, a refined model of the Shanghai Damaogang Bridge’s (hybrid beam type) box deck joints is established. The correctness of the model is verified by construction monitoring. For the front and back bearing plates, the force performance of the joint members under the most unfavorable loads is investigated, and the force transmission mechanism is analyzed. The influence of the bearing plate thickness and the joints’ stiffness on the stress distribution of the joint members, the internal force of the joints, and the force-transfer efficiency is investigated by the method of controlling variables, and the optimal structural parameters of the nodes are also studied. The results show that, within the proximity of the back bearing plate, the thickness of the back bearing plate affects stress distribution in the joint. The increased stiffness of the welding studs makes the range of shear force along the bridge direction of the top and bottom welding studs larger, and the longitudinal distribution of welding stud shear force is more uneven. The concrete structure bears a higher proportion of the internal force in the joint compared to the steel structure. Full article

The European Landscape Convention promotes the protection, management and planning of landscapes and organises international co-operation on landscape issues. Member states committed to implement measures such as promoting social education about landscapes. The convention stated that, although it was part of the education curricula in some countries, landscape education was to be expanded from a multidisciplinary perspective. The Education Act in force in Spain in 2008 (LOE, 2007), when the convention was ratified, included landscape in the syllabus, but not from as broad a perspective as that reflected in the ELC. Later education reforms have gradually increased the presence of the landscape in school curricula. This study examines landscape-related knowledge and awareness among current trainee primary school teachers, whose whole education has occurred under the umbrella of the ELC. This aims to assess whether the ELC’s targets have been met in terms of social awareness of landscape issues. A mixed questionnaire was designed, validated, and implemented in a sample of 322 students studying subjects related to the teaching of geography. The answers were analysed with descriptive and inferential statistics. The results reflect poor landscape-related knowledge and awareness, suggesting that the educational measures implemented since the ratification of the ELC have not been successful. Full article