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The energy trilemma is a critical global challenge requiring urgent resolution; however, existing solutions remain inefficient. This study utilizes a detailed environmental input-output indicator system, applying the SBM-DEA model for measurement and incorporating the Spatial Difference-in-Differences (SDID) model to assess the impact of Green Finance Policy (GFP) on environmental efficiency in Chinese cities from 2006 to 2021. The findings demonstrate that GFP significantly enhances environmental efficiency within a 500-km radius, as confirmed by various robustness tests. Mechanism analyses indicate that optimizing industrial structure, reducing energy consumption, advancing green innovation, and strengthening environmental regulations are critical pathways to improving environmental efficiency. Heterogeneity tests further examine the spatial policy effects under different factor endowments. Ultimately, the study concludes that improving environmental efficiency through GFP can alleviate the energy trilemma. This paper highlights the importance of implementing city-specific policies, offering new insights into energy economics, and providing fresh perspectives for policymakers, financial institutions, and enterprises. Despite the study's contributions, future research should further explore the comprehensive effects of GFP on energy, the environment, and the economy to provide more precise and holistic solutions for addressing the energy trilemma. • Utilizes a spatial double-difference (SDID) model, enhancing policy effect precision. • Demonstrates GFP's significant, positive impact on environmental efficiency nationwide. • Identifies a 500 km radius for GFP's optimal geographical influence. • Explores mechanisms like industrial optimization and green innovation driving efficiency. • Reveals heterogeneous effects of GFP across different urban areas. [ABSTRACT FROM AUTHOR]

Green credit plays a pivotal role in maintaining a balance between energy demand and the transition to low-carbon energy sources while considering energy conservation, emission reduction and the 'dual carbon' goal strategies. The SE-SBM model and the spatial Durbin model were used in this study to understand how green credit affects energy efficiency. The empirical approach was based on provincial panel data collected in China from 2005 to 2020. The results indicated that green credit significantly enhanced energy efficiency and had a substantial positive spatial spillover effect beyond the immediate region. Therefore, the enforcement of green credit policies could enhance energy efficiency within the region and concurrently encourage an improvement in energy efficiency in adjacent regions. Furthermore, the study unveiled significant regional disparities in the impact of green credit on the improvement of energy efficiency across the eastern, central and western regions. The green credit policies should be customized to align with the unique circumstances of different regions. Green innovation serves as the primary conduit through which green credit enhances energy efficiency. These insights offer a valuable reference for policymakers seeking to enhance energy efficiency via green credit policies. • SE-SBM,SDM and DSDM models are adopted in the analysis. • Spatial dependence exists in energy efficiency and green credit. • Green credit promotes energy efficiency through direct, indirect and spatial effects. • Green innovation play the mediation role on this relationship. • Some policy recommendations on the promotion of energy efficiency are proposed. [ABSTRACT FROM AUTHOR]

This paper presents a computational method for concrete-encased concrete-filled steel tube (CFST) columns under eccentric compression, which adopts the form of equivalent rectangular stress integrated by material constitutive curve. When establishing finite element model via ABAQUS, confinement provided by stirrup was considered to modify the constitutive law of encased concrete, so that the numerical modeling was in good agreement with tests. By analyzing the simulation results, the applicability of basic assumptions, such as plane section assumption, was discussed, and a database of 207 models with various parameters was created. The developed method took into account the influences of geometric nonlinearities of section shape, and its accuracy was verified against various collected tests and the database. It turned out that the formula presented was applicable to a wide range and had sufficient precision, while the predictions of N - M interaction curves of concrete-encased CFST columns in EC4, AISC and CECS were conservative due to the ignorance of the exact integration about irregular section-shape. • A practical design method for concrete-encased CFST columns subjected to eccentric load is introduced. • The accurate integration takes into account the irregular shape of sections. • The equivalent coefficients are uniformly expressed by simple equations, and cover the influence of important factors. • The proposed method can capture the N-M interaction of composite columns effectively. [ABSTRACT FROM AUTHOR]

When located at the base of a building experiencing high-intensity earthquakes or bi-directional earthquakes, shear walls may be tensile, resulting in tensile-flexural-shear (TFS) stress states after lateral load coupling. The Chinese code proposes the embedded steel to counteract such issues, but there are few relevant studies. Six concrete-encased steel plate (CES) walls were tested under the TFS load to investigate the effects of axial tensile ratio and steel content on seismic behavior. The results showed that TFS specimens failed in tensile flexural-shear mode. Compared to the tension-free specimen, TFS specimens with an axial tensile ratio of 2.5 had 21%, 56%, and 40% lower shear strength, initial lateral stiffness, and ductility. Comparatively, increasing the steel content in the boundary elements effectively reduced the strengthening effect of steel and the brittle fracture potential of boundary elements induced by TFS load, thus enhancing the overall behavior by 15–19%. Furthermore, the failure mechanism was proposed based on the development of deformation and strain. It demonstrated that the maximum principal tensile stress in the web caused severe shear strength degradation and highlighted the importance of the dowel action through the crack interface, depending on the variables. Through the comparative analysis of the shear strength design formulas for eccentric tensile CES walls, the steel proportion was proposed as a modified factor in Chinese code for better estimation. • Concrete-encased steel plate walls were tested under tensile-flexural-shear load. • Innovative tension loading device approximated the real loading condition. • Effects of axial tensile ratio and steel content on seismic behaviors were analyzed. • Failure mechanism revealed shear strength degradation. • Modified formula adopting the steel proportion provided better estimation. [ABSTRACT FROM AUTHOR]

Twenty four specimens were designed to investigate the axial compressive stiffness of the recycled aggregate concrete(RAC)-encased recycled aggregate concrete-filled steel tube (RACFST) composite columns. The working mechanism of the RAC-encased RACFST composite column was investigated and the full range load–displacement curves of the composite columns were obtained. The interaction of each component of the composite column, i.e. the effect of the outer RAC from the stirrup and the steel tube, and the effect of the core RAC from the stirrup and the steel tube, were analyzed. The constitutive models of the outer unconfined RAC, the outer confined RAC, the core RAC were discussed. Thereupon, simple formulas were proposed to calculate the axial compressive stiffness of composite columns. These formulas can assist engineers to predict the axial deformation of structure in high-rise buildings more accurately. • The whole load–displacement curves and failure patterns of specimens were obtained. • Working mechanism of RAC-encased RACFST composite columns was analyzed. • Constitutive models for each component of the composite columns were adopted. • The calculation methods of their axial compressive stiffness are presented and compared. [ABSTRACT FROM AUTHOR]

• The eccentric compressive behavior of RAC-encased RACFST composite columns was investigated. • The load-deformation curves of specimens were obtained, and the mechanical performance of specimens was evaluated. • A finite-element model was developed to analyze the behavior of specimens under eccentric loading. • Current design provisions were compared, and design recommendations for specimens were presented. Recycled aggregate concrete (RAC) was mainly limited to the nonstructural uses in practice due to its inferior properties. To expand the range of application of RAC, a novel structure type of concrete-encased concrete-filled steel tube (CFST) has attracted great interest due to its excellent performance. Since little literature about the behavior of the RAC-encased RACFST, it is imperative to conduct research about the new type of member for practical application to meet the requirement of the large market and sustainable development. This paper presents experimental and analytical studies on the mechanical behavior of RAC-encased, RAC-filled steel tube (RACFST) composite columns under combined compression and bending. In the experiments, sixteen specimens were tested under axial or eccentric compression to investigate the effects in the recycled coarse aggregate (RCA) replacement ratio (0%, 25%, 50%, 75%, 100%), eccentricity ratio (e/h = 0, 0.2, 0.4, 0.6), steel ratio (2.72%, 2.11%), and slenderness (l / h = 3, 6, 9) on their mechanical performance. The results indicated that the replacement ratio of RCA had little effect on the failure mode of the RAC-encased RACFST composite columns. Compared with the specimens under axial compression, reductions of 23.1%, 63.9%, and 72% were observed in the compressive strength for specimens with eccentricities of 0.2 h , 0.4 h , 0.6 h , respectively. Both the increase in the steel ratio and the reduction in the slenderness significantly improved the compressive strength of the specimens. A finite-element model of the specimens was developed to predict the load-deformation relationship and failure mode. The ultimate bearing capacity was predicted using existing design codes and the test result were compared. The values predicted by the design codes EC4, AISC360 PSD, and CECS188 showed deviations <15% (relative to the experimental values), which could be considered overconservative for the bearing capacity of RAC-encased RACFST composite columns. [ABSTRACT FROM AUTHOR]

• Axial compressive behavior of RAC-encased RACFST composite columns was investigated. • The whole load-deformation curves and mechanical performance of specimens were obtained. • The calculation methods of their bearing capacity are presented and compared. A new type of composite column, recycled aggregate concrete (RAC)-encased recycled aggregate concrete-filled steel tube (RACFST) composite columns, promotes the RAC extensive utilization considering synergistic effect between the RAC and the steel tube, which is an attempt to develop environmentally sustainable concrete in high-rise buildings. In this paper, experimental research investigated the axial compressive behavior of RAC-encased RACFST composite columns. Twenty 1:3-scaled specimens were fabricated to test until failure under axial compressive loading. The main variable parameters affecting the behaviour of specimens were recycled coarse aggregate replacement ratio (range from 0% to 100% with 10% increase), stirrup spacing (s = 50 mm, 70 mm, 100 mm, 120 mm), diameter of steel tube (D = 89 mm, 114 mm), concrete strength grade (RC40, RC60) and longitudinal reinforcement ratio (4 12, 8 12). The failure modes, the whole load-deformation curves and the mechanical performance of specimens were also obtained based on static loading experiments and theoretical analysis. It was found that RAC-encased RACFST composite columns, which were subjected to identical axial loads, exhibited more favorable bearing capacity and deformation than those of a comparative reinforced recycled aggregate concrete columns (RACC). The replacement ratio of RCA had a slight effect on the mechanical performance of RAC-encased RACFST composite columns, the optimal substitution ratio of RCA was 50–60%. Based on the previous theory of superposition, the concrete cover is considered, and a calculation formula with double reduction coefficients of the axial load-bearing capacity of composite columns is proposed. Compared to the simplified superimposition method and the Chinese code Technical specification for steel tube-reinforced concrete column structure (CECS188:2005), the calculated results of axial compression bearing capacity by the proposed formula are in more agreement with the experimental values, with errors no greater than 15%. [ABSTRACT FROM AUTHOR]

• A finite element model was developed to simulate the seismic performance of PFCFS walls. • Load-deformation curve, lateral stiffness, shear capacity, and ductility of the PFCFS walls with different design parameters were compared. • Formulas for predicting the lateral stiffness and shear capacity of PFCFS walls were modified. To conduct in-depth research on the seismic performance of phosphogypsum (PG) filled cold-formed thin-walled square steel tube (PFCFS) composite walls, a series of finite element analyses were conducted using the software ABAQUS. The study examined various factors, including PG strength, oriented strand board (OSB) configuration and thickness, stud strength and thickness, screw spacing, axial force ratio, wall sheathing coverage, and height-width ratio. After summarizing, the main findings are as follows: the lateral behavior of walls is significantly affected by PG strength and wall stud thickness, while wall sheathing configuration has a relatively low impact; increasing PG strength, wall stud thickness and strength, wall sheathing thickness, axial force ratio, and the number of wall sheathings (non vs. single vs. double sheathing), or decreasing self-tapping screw spacing and wall height-width ratio enhance the shear capacity of the wall; increasing PG strength, wall sheathing thickness, or reducing wall height-width ratio improve the lateral stiffness and ductility of the wall; increasing wall stud thickness and adding more wall sheathing can improve the lateral stiffness of the wall. However, this can reduce the wall's ductility; by decreasing self-tapping screw spacing or increasing axial force ratio, the lateral stiffness and ductility of the wall exhibit an increasing-then-decreasing trend; increasing wall stud strength does not significantly affect the lateral stiffness of the wall, but it does decrease the ductility. Finally, the simulated lateral stiffness and shear capacity of the wall were compared with the theoretical values, which showed good agreement. [ABSTRACT FROM AUTHOR]

• A rectangular spiral stirrup was proposed to improve the ductility of HSC structures. • The seismic resistance capacity of SRHC columns are investigated and analyzed. • The SRHC columns with rectangular spiral stirrup exhibit good deformation. In this paper, several experimental investigations on seismic resistance capacity of steel reinforced high-strength concrete (SRHC) columns with rectangular spiral stirrups are presented. Tests were carried out on eleven SRHC columns with rectangular spiral stirrups and one comparative SRHC column with an ordinary stirrup arrangement under low reversed cyclic loading to investigate their failure patterns, characteristic loads and displacements, hysteresis loops, skeleton curves, inter-story drift ratios and ductility coefficients, energy dissipation capacities and stiffness degradation. Range analysis and variance analysis methods were used to analyze the data from the experiments. The results showed that the failure patterns of the test specimens changed from shear baroclinic failure to shear-bond and flexural failure, as the shear span ratio was increased. In addition, the shear span ratio is the main factor that had a significant effect on the carrying capacity of the test specimens. The carrying capacity of the SRHC specimens increased gradually, but their ductility decreased as the axial compression ratio was increased. The ductility coefficients of the SRHC specimens with the normal stirrup and the rectangular spiral stirrup were 3.01 and 3.27, respectively, indicating that the columns with the rectangular spiral stirrup had better deformation capacity. Furthermore, the inter-story drift ratios of all the columns with the rectangular spiral stirrup in elastic phase and elastic-plastic phase were in the range of 1/200 to 1/66 and 1/26 to 1/17, respectively, which are much larger than the limit value specified by the seismic design code. In addition, the SRHC columns with rectangular spiral stirrups exhibited plumper hysteresis curves and higher energy dissipation than the SRHC column with ordinary stirrup. Thus, the SRHC columns with rectangular spiral stirrups showed good seismic resistance capacity. [ABSTRACT FROM AUTHOR]

Optimal selection of concrete aggregates can promote sustainable construction practice from the bottom line, which is a feasible strategy to cope with resources crisis and solid waste pollution. In this study, a two-level tree structure framework was thus proposed for the sustainability assessment of lightweight aggregates (LWA) based on the life cycle assessment concept. The evaluation system was divided into four criteria categories marked as society demands, economic costs, environmental impacts and technical performance, and each of them was assigned a number of sub-index. A qualitative questionnaire survey with seven sub-index and a quantitative calculation with eight sub-index were executed in the target system. Sintering fly ash aggregates (SFFAA), cold-bonding fly ash aggregates (CBFAA), waste clay brick aggregates (WCBA) and natural pumice aggregates (NPA) were chosen as typical artificial and natural lightweight aggregates objectives and evaluated in the framework. Impact and sensitivity analyses were conducted to comparably discuss the sustainability of various lightweight aggregates. The impact analyses represented that the waste clay brick aggregate has better sustainability. The sensitivity analysis shows that the supply-demand relationship of raw materials greatly impacts the sustainability of lightweight aggregate, and the transportation distance of raw materials is the critical factor in the production of LWA. At the same time, artificial lightweight aggregates are sensitive to cement binder consumption, and zero cement addition or waste cement powder is an optimistic option. From the sustainable life cycle assessment results, waste clay brick aggregates, sintering fly ash aggregates and cold-bonding fly ash aggregates are suggested as the alternative to the natural pumice aggregates for the lightweight aggregates concrete production. The emphasis on the weight of the social dimension will tend to prefer the selection of SFAA, and the economic or environmental dimension will lead to the preference of CBFAA for sustainable development. The framework proposed in this work could be used in choosing other sustainable construction materials or cleaner products. [Display omitted] • A two-level tree structure framework proposed for sustainability assessment. • Sintering, cold-bonding, recycled, and natural aggregates evaluated in framework. • Impact and sensitivity analyses conducted to comparably discuss sustainability. • Greater sustainability possessed by artificial aggregates than natural ones. • Sustainability of artificial aggregates impacted by binder and transportation. [ABSTRACT FROM AUTHOR]

Self-centering (SC) precast concrete wall structures have been developed as an earthquake resilient structural system characterized by low structural damage and controllable residual drift. Despite the superior structural performance, harmonizing to seismic performance between structural and non-structural components is expected to be considered for further comprehensive performance assessment. This paper extensively evaluates the seismic demands of structural and non-structural components, especially for those sensitive to accelerations in SC precast concrete wall structures. Factors considered include building heights, earthquake ground motion types and intensities, energy dissipation, as well as base rocking, and impact against the foundation. The seismic demands of SC precast concrete walls are firstly compared with conventional reinforced concrete (RC) walls by nonlinear time history analysis (NTHA) in terms of displacement and acceleration responses. Then, attention is focused on investigating the dominant factors for the seismic demands of acceleration-sensitive non-structural components in SC precast wall structures through floor response spectrum analysis and parametric analyses. The results confirm that the SC precast walls exhibit excellent lateral response, especially with limited residual drifts. However, for the floor acceleration response, which is highly related to the demands of non-structural components, the results show that higher modes have a critical influence on SC precast wall structures. It also indicates that the floor acceleration response of SC precast wall structures is strongly influenced by the location of the story levels but not strongly influenced by the base rocking impact and energy dissipation capability. • Seismic demands of structural and non-structural components for self-centering (SC) precast wall structures are evaluated. • Influences from higher mode effects to the floor acceleration responses of SC wall structures are investigated. • Effects of different conditions on the seismic responses of SC precast and conventional RC walls are studied. • The non-structural responses in SC precast wall structures do not significantly increase after impact on foundation. [ABSTRACT FROM AUTHOR]

This study primarily investigates the seismic fragility of mainshock damaged self-centering (SC) hybrid precast walls in aftershocks, and the results are compared with equivalent conventional reinforced concrete (RC) walls. A 5-story case-study structure is selected and designed comparatively using SC walls and RC walls to resist all the lateral seismic forces for design requirements. Thereafter, nonlinear time history incremental dynamic analyses (IDA) are conducted for the two analytical wall models using 44 artificially constructed seismic sequences. In the first step, mainshock IDA analyses are performed followed by aftershock IDA analyses considering different mainshock damages on the considered wall models. Three mainshock damage levels relating to three distinct post-mainshock inter-story drift ratios are induced in both wall models. The IDA curves in terms of maximum inter-story drift and residual drift are produced and comparatively studied for both wall models at predefined mainshock damage levels. The results are investigated and compared regarding seismic collapse capacity, residual drift, and effects of the polarity of aftershocks. It indicates from the study that in a general sense, the SC walls and RC walls exhibit similar collapse capacities for both undamaged conditions (i.e., subjected to mainshock only) and damaged conditions (with distinct mainshock damage levels). However, SC walls are intrinsically designed with significantly reduced residual drifts (proved again in this study), which results in much less influence from the aftershock polarity as compared to RC walls. • Seismic responses of self-centering (SC) hybrid precast concrete walls under mainshock-aftershock seismic sequences are extensively investigated. • Two different approaches are used to design case-study walls and the effects of that for the two wall systems are assessed through fragility analysis. • Effects of various initial mainshock damage levels and aftershock polarity on seismic fragility of SC hybrid precast walls and conventional RC walls are investigated. [ABSTRACT FROM AUTHOR]