In the electronics industry, the efficient recovery and capture of sulfur hexafluoride (SF6) from SF6/N2 mixtures is of great importance. Herein, three metal–organic frameworks with fine‐tuning pore ...structures, Cu(peba)2, Ni(pba)2, and Ni(ina)2, were designed for SF6 capture. Among them, Ni(ina)2 has perfect pore sizes (6 Å) that are comparable to the kinetic diameter of sulfur hexafluoride (5.2 Å), affording the benchmark binding affinity for SF6 gas. Ni(ina)2 exhibits the highest SF6/N2 selectivity (375.1 at 298 K and 1 bar) and ultra‐high SF6 uptake capacity (53.5 cm3 g−1 at 298 K and 0.1 bar) at ambient conditions. The remarkable separation performance of Ni(ina)2 was verified by dynamic breakthrough experiments. Theoretical calculations and the SF6‐loaded single‐crystal structure provided critical insight into the adsorption/separation mechanism. This porous coordination network has the potential to be used in industrial applications.
The metal–organic framework (MOF) Ni(ina)2 has pore sizes (6 Å) that are perfectly compatible with the kinetic diameter of sulfur hexafluoride (5.2 Å), affording the benchmark binding affinity for this potent greenhouse gas that is used in the electronics industry.
Current automated structural topology design methods can only deal with limited design spaces or simplified architectural layouts for lack of data or a proper representation of structure topology. To ...address this, the abundant information of manually designed architectural and structural layouts should be exploited to guide the topology design. To achieve automatic generation of structural topologies according to real‐world architectural layouts, this research introduces StrucTopo‐generative adversarial network (GAN), an end‐to‐end generative model with node and edge generation stages based on proper graph representation. Nodes are generated using an image‐to‐image translation model, and edges are generated with a GAN‐based approach. The model is trained and tested on a dataset of 300 complex architectural and structural layouts. Measured against the manually designed topologies, the results indicate that the proposed model can generate reasonable structural topologies, with a recall of 97% and an intersection‐over‐union of 80% in node generation, with a precision of 92% and a recall of 91% in edge generation. Additionally, the joint generation shows a graph similarity of 72%. The proposed model is the first of its kind to consider complex architectural layout constraints in the generation of structural topology, marking a step forward in applying artificial intelligence to practical structural design.
•A test on a large-scale composite frame with wide floor slabs is conducted.•The effect of floor loads on the seismic behaviour of the frame is considered.•The weld fracture near exterior joints ...impacts the global performance greatly.•The effective slab width is 0.75 times column width with obvious shear lag effect.•Deformation characteristics and force mechanism under cyclic loading are discussed.
The steel–concrete composite frame systems are widely used in multistory and high-rise buildings owing to good mechanical performance and high construction efficiency. In previous research on the composite frame systems, many lateral cyclic tests were conducted on specimens with small-width floor slabs without floor loads, which could not precisely reflect the actual behaviour of composite frames in spatial multistory buildings. Therefore, this paper presents an experimental study on the seismic behaviour of composite frames with wide floor slabs considering the effect of floor loads. The specimen was a two-story two-span composite frame with the scale ratio of 0.5, and three load cases, including the vertical floor loading test, the lateral cyclic loading test and the pushover test, were respectively applied to investigate the mechanical performance of the composite frame. The slab crack development, mid-span deflection and strain distribution of slab reinforcements in the vertical floor loading test were discussed. The overall responses of the specimen in the lateral cyclic loading test and pushover test were analysed, including failure phenomena, load–displacement curves, strength and stiffness degradation, energy dissipation capacity and deformation characteristics. Moreover, the seismic performance of columns, beams, slabs and joints in the specimen was discussed in detail and the force mechanism of the composite frame was revealed based on the structural analysis of components. The results indicated that the specimen exhibited sufficient load-bearing capacity, good ductility, stable strength and stiffness degradation and excellent energy dissipation capacity under the combination of vertical floor loads and lateral loads. The welds at the bottom flange near the exterior joint fractured under cyclic loading, which was found to have significant influence on the deformation pattern and force mechanism of the composite frame. The shear lag effect was obvious in the wide floor slabs and the effective width of the slabs was estimated to be nearly 0.75 times the column width.
•The S-C–W-B criterion is inadequate for avoiding the column hinges in RC frames.•A biaxial bending strength model of RC columns under axial load is developed.•A biaxial overstrength factor is ...proposed to improve the S-C–W-B criterion.•The inelastic response of RC frames under biaxial seismic excitation is investigated.•The effect of the biaxial overstrength factor is validated by FEM analysis.
In several earthquakes, numerous reinforced concrete (RC) frames subjected to seismic excitation exhibit a collapse pattern characterised by column hinges, although these frames are designed according to the strong-column–weak-beam (S-C–W-B) criterion. The effect of biaxial seismic excitation on the disparity between the design and the actual performance of RC frames is investigated in this study. First, a modified load contour method was proposed to derive a closed-form equation of the biaxial bending moment strength, which was verified based on numerical and experimental results. Subsequently, a group of time-history analyses of a simple frame modelled using fibre beam-column elements subjected to biaxial seismic excitation were conducted to verify that the current S-C–W-B criterion is inadequate for preventing the occurrence of column hinges. A biaxial overstrength factor was developed based on the proposed equation, and the reinforcement of columns was appropriately amplified using this factor to prevent the occurrence of column hinges under biaxial excitation; this approach was proved to be effective through another group of time-history analyses. Thus, the findings of this study can serve as a basis for improving the seismic design of RC frames, which will enable the construction of safer engineering structures.
AbstractThe steel–concrete–steel (SCS) sandwich composite structures with orthogonal longitudinal and transverse (bidirectional) steel webs exhibit superiorities in strength, ductility, impact ...resistance, blast resistance, and construction efficiency compared with the traditional engineering structures, offering a competitive alternative for applications such as submarine tunnels, nuclear shells, protective structures, offshore structures, etc. While there were several practices in engineering, the current design method is an application of the concrete code and there are few experiments that could support the design theory especially for the shear resistance. Unlike RC beams or steel beams, the SCS composite structures with bidirectional steel webs have multiple shear force transferring mechanisms, and it is of importance to investigate the contributions of the different mechanisms and how they work together as a composite structure. To address this problem, 16 shear tests of SCS composite structures with bidirectional steel webs were carried out and theoretical analysis was conducted. The shear resistance is categorized into three mechanisms: the composite truss, the pure shear of the axial web, and the dowel action of the flange. Then the theoretical method to predict the shear resistance considering the coworking of different mechanisms is proposed and compared with existing methods. It is proved that the proposed method reveals the antishear mechanism and is of satisfactory accuracy.
AbstractFour shear-critical RC shear walls were tested under a tension-bending-shear load to replicate seismic behavior of the bottom shear wall in high-rise buildings. The axial tension ratio ranged ...from 0 to 0.5 and the aspect ratio was 1.06. The shear compression failure mode was observed for each specimen, characterized by the formation of an inclined crack at 45° and direct strut action. The shear displacement was a dominant deformation component throughout the loading history. When the axial tension force increased from 0 to 1,293 kN, the ultimate drift ratio increased from 0.90% to 2.38%, while shear capacity linearly decreased from 1,507 to 895 kN. The load–displacement curve showed a significant pinching effect and strength degradation effect. In addition, this paper reports an innovative experimental method to obtain shear resistance of transverse reinforcement (Vs) based on the plasticity theory and strain measuring result. Test results using this method show that not all horizontal distributed rebar yield simultaneously at the ultimate capacity. The US code-specified shear strength contribution of horizontal distributed rebar was found to be unsafe for each test specimen. Finally, a database of RC shear walls subject to combined tension-bending-shear load was established to evaluate shear strength formulas in design codes. The comparison showed the Chinese code predicted spuriously higher tension-shear capacity, while the US code predicted conservative capacity. Based on the developed database, a simplified design formula is proposed with adequate safety concerns and accuracy.
AbstractSteel-concrete-steel (SCS) composite structures with bidirectional steel webs and ribs exhibit superior performance in capacity, rigidity, ductility, blast resistance, waterproofness, and ...construction efficiency compared with traditional engineering structures, making them especially suitable for megaprojects, such as submarine tunnels, nuclear shells, and offshore structures. The current design method is mainly an adaptation of reinforced concrete code, and studies to investigate the distinctiveness of the structure considering the composite action are needed. Seven bending tests were conducted and numerical models developed to study the bending behaviors of SCS composite structures. The major concerns were local buckling behavior and casting imperfection, which are rarely studied but of importance in practice. It was found that the biaxial strengthening effect due to lateral constraint plays an important role and should not be neglected especially in the tension flange, which typically offers an enhancement of about 15% in strength at the ultimate state. Based on the experimental, numerical, and theoretical analyses, suggestions are proposed to modify the current design method which clarify construction requirements considering local buckling and casting imperfection. These modifications have been proven to provide approximately 10% improvement compared with the experiments.
Shear strength of trapezoidal corrugated steel webs is an important issue for the design of box girder bridges with trapezoidal corrugated steel webs. Eight H-shape steel girders with trapezoidal ...corrugated webs are firstly tested to investigate the shear behavior of webs. An extensive parametric study based on the linear elastic buckling analysis is then conducted to derive the simplified formula for calculating the elastic shear buckling strength of trapezoidal corrugated steel webs considering three different shear buckling modes. The proposed formula can give more satisfactory results for predicting the elastic shear buckling strength than some available formulae provided in the literature when compared with the numerical results. Furthermore, the nonlinear buckling analysis is conducted to intensively investigate the shear strength associated with initial geometric imperfections, and the formulae of the shear strength are proposed. Good agreements can be observed between the results calculated using the proposed prediction formula in this paper and the experimental results, and a design formula is also recommended for the routine shear design of trapezoidal corrugated steel webs.
•Test on shear behavior of trapezoidal corrugated webs is conducted.•Formula for calculating elastic shear buckling strength is derived.•Influence of initial geometric imperfections on shear strength is investigated.•Prediction formula and design formula of shear strength are proposed.
An innovative composite structural system with separated gravity and lateral resisting systems (SGLR system) was proposed to overcome the shortcomings of existing prefabricated structural systems. ...Two representative frame specimens with a scale ratio of 0.5 were tested under vertical floor loads and lateral cyclic loads to investigate the mechanical behaviour of the SGLR system. The slab crack patterns, failure modes, load–displacement curves, strength and stiffness degradations, energy dissipation capacity, deformation characteristics and strain development were analysed. The experimental results showed that the bent frame specimen (SGLR-1) exhibited good and stable seismic performance and the shear wall–bent frame (SGLR-2) with higher stiffness and capacity demonstrated obvious degradation due to buckling and fracture of steel plates at the bottom of shear walls. From test observations, flexural deformation was the dominated deformation pattern of the SGLR system under lateral loads. On the basis of test data, seismic performance assessment indicated that the SGLR system had larger safety margin than the conventional composite rigid frame (RF) system with the same design criteria of inter-storey drift ratios. The internal force analysis of the SGLR system showed that the base shear distribution in shear walls and columns varied with the increase of overall drift ratio. Moreover, it was revealed from the experimental analysis that the semi-rigidity of connections was significant and had conspicuous influence on both gravity and lateral force transfer mechanisms of the SGLR system.
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•An innovative structural system is proposed to improve prefabricated construction.•Tests on two representative frame specimens with a 0.5 scale ratio are conducted.•The new system has larger safety margin than the conventional rigid frame system.•The base shear distribution in walls and columns varies with loading amplitude.•Semi-rigidity of connections is significant and affects force transfer mechanisms.
AbstractSteel plate reinforced concrete (SPRC) composite shear walls, which are composed of steel columns embedded in boundary elements and an embedded steel plate in the wall web, have been used in ...super-high-rise buildings. When subjected to rare earthquake loads, combined tension-bending-shear actions are often generated in the shear walls of super-high-rise buildings because of the increasing demand for a greater height–width ratio. Based on quasistatic tests on seven SPRC shear walls under tension-bending loads, the seismic behavior of SPRC shear walls with various steel-content ratios and axial tension ratios was investigated. The failure mode, strength and displacement capacity, stiffness degradation, shear deformation, damping coefficient, strain, and cracking of each test specimen are presented in detail. The failure mode is divided into tension-bending failure, anchorage failure, and torsional buckling failure according to the test results. The strength, stiffness, and ductility of the SPRC shear walls were significantly reduced with an increase in the axial tension ratio. The fiber beam-column finite-element (FE) model was simulated using MSC.MARC software. A comparison showed that the FE model predicted the load-displacement relationship, stiffness degradation, and ultimate capacity with a reasonable level of accuracy. Based on the test results, a design method is proposed for predicting the ultimate strength of the SPRC shear walls under tension-bending combined loads, and recommendations for improved anchorage design are proposed.
