This study investigates the crashworthiness of corrugated beam guardrails through nonlinear dynamic simulations. A novel design incorporating double anti-blocking blocks is proposed and evaluated. The analysis reveals that while conventional guardrails satisfy basic buffering requirements, they exhibit problematic wheel-column blocking phenomena. Key findings demonstrate that vehicle kinetic energy is predominantly transformed into deformation energy, with reduced energy variation facilitating safer vehicle redirection. Critical thresholds are identified at impact velocities exceeding 120 km/h or collision angles >= 25 degrees, where blocking effects intensify significantly, often preventing successful vehicle redirection and causing substantial front-end deformation. Parametric studies establish an inverse relationship between structural thickness (both columns and plates) and energy absorption capacity. The research determines optimal material specifications: columns perform best at 4.5 mm wall thickness (with 5.0 mm as the upper limit), while guardrail plates should maintain a minimum 3.0 mm thickness. The innovative double-block design demonstrates remarkable improvements, achieving a 30.7 % reduction in peak collision forces while completely eliminating blocking issues. Energy distribution analysis shows the new configuration reduces the vehicle's share of total deformation energy from 75.7 % to 68.7 %, indicating enhanced energy absorption by the guardrail system itself. These findings provide valuable engineering guidelines for optimizing highway safety barrier performance under various impact scenarios.

This study investigates the stability performance of a single arch ribbed steel box tied arch bridge using the Zhengzhou Xincaihong Bridge as a case study. A comprehensive analysis is conducted employing both ANSYS beam element modeling and multi-scale plate-beam modeling of instability-prone regions. The elastic stability analysis reveals that the structure exhibits relatively low lateral bending stiffness, with the first five instability modes all manifesting as out-of-plane buckling of the arch ribs. While geometric nonlinearity demonstrates minimal influence on structural stability, material nonlinearity emerges as the predominant governing factor. Under combined dead load and full live load conditions, the most critical instability position occurs at L/5 (L refers to the span of the side span) of the side arch rib. Parametric studies identify the bending stiffness of side span arch ribs and the rise-span ratio as the most significant factors affecting overall stability. Comparative analysis between modeling approaches shows that multi-scale models predict lower live load ratios than conventional beam elements, with reductions of 2.21% at the mid-span segment and 13.09% at the L/5 section, demonstrating that simplified beam models are not conservative and overestimates structural capacity by neglecting local instability effects. The research further quantifies the impact of key design parameters: structural stability improves with increasing diaphragm quantity (1-3), longitudinal stiffener plate thickness (12-18 mm), and number of top plate stiffeners (2-5 per side), as evidenced by corresponding increases in live load ratio coefficients.

To address the challenges of high cost and poor durability of steel temporary bridge decks in marine "highhumidity + high-salinity" environments, as well as the heavy self-weight and low crack resistance of ordinary concrete bridge decks, this paper proposes a novel lightweight, economical, and high-strength thin UHPC bridge deck with cavities and investigates its longitudinal bending performance. Bending tests were conducted on two members with different UHPC fiber types and cover layer thicknesses. The effects of cavity spacing, bridge deck height, and cover thickness on flexural performance were investigated using finite element models. The results show that the fiber type of UHPC and the cover layer thickness at the bottom of the cavity exert a substantial influence on the longitudinal flexural performance of the member. Compared with member L-B, L-S exhibited a 265.4% increase in cracking load and a 162.7% enhancement in ultimate bearing capacity. Finite element analysis shows that increasing the bridge deck height significantly enhances both the ultimate load and ductility, while increasing cavity spacing reduces them, and cover thickness changes have minimal impact. According to the experimental results and failure modes, a predictive formula for the ultimate load of thin UHPC bridge deck with cavities in longitudinal bending was established. It was verified through experimental and numerical results, and the maximum deviation of the prediction results was 6.8%.

This study centers on the Binzhou no. 4 Bridge and proposes an innovative steel-ultrahigh-performance concrete (UHPC) composite joint, serving as a pivotal component of multilong-span continuous hybrid girder bridges comprising integrated prestressed concrete (PC) and steel-UHPC girders. The structural response was systematically analyzed and interpreted through negative bending tests on a 3:1 scaled-down model coupled with finite-element analysis, with particular emphasis on flexural performance, cracking load, failure modes, and force transfer mechanism. Finite-element analysis incorporating varying UHPC parameters was performed. The ultimate bearing capacity of the composite beam reaches 580.3 t. Attributable to shear-induced failure of the PC beam, the most unfavorable position of the steel-concrete composite beam transitions from the pure bending section to the shear span section. The bearing plate and shear studs dominate the force transmission. The incorporation of the UHPC layer substantially mitigates the loads borne by each structural component, while the extension length of the UHPC layer on the concrete beam exhibits negligible influence on the forces acting upon these components. Furthermore, the ultimate bearing capacity of the steel-concrete composite beams was computed, demonstrating excellent consistency with finite-element simulation outcomes. The disparity between the calculated and the simulated values remains below 10%.

The Ultra-High Performance Concrete (UHPC) Hollow-Core Bridge Deck (UHPC-HCBD) is a structural system for steel girder bridges, developed to address the poor corrosion resistance and cracking susceptibility of conventional decks in marine environments. This system features a hollow-core UHPC layer reinforced with a steel wire mesh. Initially, finite element analysis was conducted to determine the critical local load magnitudes and locations. Subsequently, four full-scale UHPC-HCBD specimens were tested for local compression stability. The main variables included the fiber type (steel or basalt) incorporated into the UHPC and the loading position. Specimen performance was evaluated through failure modes, load-deflection curves, strain distribution, and crack patterns, focusing on their influence on cracking stress and ultimate bearing capacity. Results show that steel fiber specimens, compared to their basalt fiber counterparts, exhibited significantly higher cracking stresses by 380.8 % and 88.8 %, and ultimate bearing capacities by 252.9 % and 353.1 %, when loaded at the midspan of the inverted triangle and the apex of the triangle, respectively. The inclusion of steel fibers effectively enhanced both ultimate capacity and ductility. A proposed design formula for the ultimate bearing capacity of the UHPC-HCBD shows good agreement with experimental values.

This study investigates the dynamic amplification effect of the main girder of cable-stayed bridges after cable rupture. The expression for the dynamic amplification effect is derived using the modal superposition method, and the influence of the duration of cable rupture on the dynamic amplification effect is investigated. The results indicate that, for a single-degree-of-freedom (SDOF) system without damping, the displacement dynamic amplification factor (DAF) can reach a maximum of 2.0. For the main girder of cable-stayed bridges, the dynamic amplification factor can exceed 2.0 and is related to the weight of the projection components of the response on the mode shapes. Using the modal superposition method of calculation, the higher-order modes have the greatest influence on shear force, followed by the bending moment, while they have the least influence on displacement. The theoretical derivation is validated using a simplified model, and it is shown that the commonly used equivalent static load calculation method with a factor of 2.0 for the static cable force poses potential safety risks. Furthermore, this study shows that the shorter the duration of cable rupture, the more pronounced the dynamic amplification effect. It is recommended that the duration of the cable rupture should not exceed 0.01 times the fundamental period of the structure when the maximum impact effect is calculated to ensure the rationality of the calculation results.

Metal halide perovskites have attracted much attention due to their properties and wide applications in optoelectronic devices. B-site ion substitution, especially heterovalency substitution, is proven to be one of the practical approaches to modulate lattice structure and improve physicochemical properties. Here, lattice and bandgap modulation in all-inorganic perovskites CsPbX3 are achieved by substituting Pb2+ with Bi3+. A series of CsPb1-xBixBr3 (0 <= x <= 1) microplates with the x values precisely tuned are prepared by a chemical vapor deposition (CVD) method. The lattice structure varies from single crystal CsPbBr3 with a cubic structure to the single crystal Cs3Bi2Br9 with a hexagonal structure. Correspondingly, three photoluminescence (PL) bands gradually emerge during the substituting: green, blue, and broad red-to-near-infrared emission. From micro-area photoluminescence spectra as a function of excitation power and temperature, combined with time-resolved PL characterization, the emission bands are confirmed from band-edge and self-trapped excitons (STEs) emission. From density functional theory (DFT) calculations, the STE emission in CsPb0.9Bi0.1Br3 and CsPb0.1Bi0.9Br3 is highly related to a combined defect contributed by bromide vacancy and the substitution of B-site ions. This study paves a new way for expanding the spectral range of perovskite emitters and even preparing white light-emitting devices.

The non-cell steel-concrete composite joint, serving as a critical nodal point in hybrid beam structures, features an innovative configuration and experiences intricate stress distributions. This study delves into the stress characteristics of the steel-concrete composite joint and scrutinizes the impact of key design parameters such as the thickness of steel flanges, web thickness and prestressing loads. The results indicate that augmenting the thickness of steel flanges promotes more uniform load transmission to the compression plate, with recommended thicknesses ranging from 18 mm to 22 mm. Furthermore, appropriately augmenting prestressing loads can effectively mitigate phenomena such as debonding between concrete and the compression plate and pullout of anchor bolts.

This paper proposes an innovative steel-UHPC-concrete composite joint (SUCCJ), which is a key part of multilong span continuous hybrid girder bridges (CHGBs) composed of PC girder and steel-UHPC girder. Structural responses were analyzed and discussed by a negative bending test of a scaled model (6333 mmx2084 mmx1354 mm) and finite element analysis (FEA), focusing on flexural performance, cracking load, failure mode, and force transmission mechanism. The results indicate that when the load is 3750 kN (2.6 times the design load of 1440 kN), the load-midspan displacement curve of the SUCCJ is still in the linear elastic stage, which exhibit sufficient strength and excellent deformation performance. The ultimate bearing capacity of the SUCCJ is 6366 kN and is destroyed due to extensive tensile damage to the top plate of the PC girder. The bearing plate and shear studs dominate the force transmission, and their force transmission proportions are 54.98 % and 24.03 % respectively. The proportion of axial force undertaken by UHPC layer slowly increased to 10.1 % as it away from the bearing plate. In addition, Combining FEA with theoretical calculations, the calculation theories of cracking moment and ultimate bearing capacity of the SUCCJ were proposed. The theoretically calculated values of the cracking moment and ultimate bearing capacity of the SUCCJ are in good agreement with the FEA values, and the differences are 4.8 % and 8.3 %, respectively.

UHPC provides a new solution for reinforcing damaged RC bridge decks due to its ultra-high strength and durability. However, the crack performance of RC beams with varying damage degrees reinforced by UHPC layers employing different parameters remains unclear, and there is a lack of predictive formulas for estimating the maximum crack width. This paper aims to elucidate the flexural behaviors (e.g., Flexural cracking behavior, ultimate capacity, and crack width) of RC beams with different pre-damage degrees strengthened by UHPC. The influence of main design parameters such as the pre-damage degrees of RC beams, the UHPC layer thickness, and the reinforcement ratio on crack behavior was investigated. The experimental results show that the cracking load and ultimate load of pre-damaged RC beams strengthened by the UHPC layer have been significantly improved. Reducing the pre-damage degree of RC beams and increasing the reinforcement ratio of the UHPC layer could enhance the strengthened beams' cracking load and ultimate load. However, as the thickness of the UHPC layer increases, the ultimate load increases, but the cracking load decreases. Based on the experimental results, a formula for the maximum crack width on the UHPC surface of the UHPC-RC composite beam was proposed. Experimental results and related literature verify the applicability of the formula, and the formula has good accuracy.

A strategy of lanthanide-ion doping into dual-halogen-alloyed perovskites CsPb(XxY1-x)3 (X, Y = Cl, Br, I) via chemical vapor deposition is introduced, obtaining a series of high-quality, stable microplates. Under continuous light excitation, each sample exhibits highly stable dual-band photoluminescence emission, whereby pairwise combinations of the three halogens enable photoluminescence to cover the red, green, and blue spectral regions. Corresponding high-performance dual-wavelength lasers are achieved. The segregated phase domains are tens of nanometers in size with well-defined boundaries. Theoretical calculations indicate that lanthanide-ion doping promotes phase segregation and facilitates ion migration in the alloyed case, while suppressing it in the phase-segregated state, producing a phase-pinning effect. This mechanism imposes opposite trends on the migration barrier in alloyed versus deployed domains, simultaneously driving halide segregation and pinning ion migration in segregated phases. Our work simultaneously enhances stability and broadens the bandgap-engineering for lead-halide perovskites, accelerating their entry into next-generation optoelectronics. He et al. report a lanthanide-doping strategy for dual-halogen-alloyed perovskite microplates, which promotes phase segregation and facilitates ion migration in the alloyed case, while suppressing it in the phase-segregated state, resulting in dual-wavelength lasing in visible spectral region.

Tin-based halide perovskites (ASnX3) have garnered substantial interest due to their unique photoelectric properties and environmentally friendly features. The A-site ions tuning strategy has been proven to promote material performance. However, there is a lack of systematic research on the optical properties, lattice structure variation, and band structure evolution in tin-based perovskites when the A-site ions tune from organic to inorganic. Herein, MA1-xCsxSnBr3 and MA1-xCsxSnI3 (0 <= x <= 1) flakes are synthesized through a one-pot reaction method. By controlling the Cs ratio, a tunable photoluminescence (PL) emission covering a wide range of 560-685 nm can be observed in MA1-xCsxSnBr3, with bandgap tuned from 1.8 to 2.15 eV, while the PL ranges from 900 to 950 nm with the bandgap 1.2-1.3 eV for MA1-xCsxSnI3. Besides, the PL intensity of MA1-xCsxSnBr3 significantly enhances with the increasing Cs ratio. First-principles calculations reveal that the octahedron shrinks gradually as the Cs ratio increases. It increases the orbital overlap between Sn and Br and causes a symmetry variation, thus decreasing the bandgap and increasing emission intensity. This work reveals the photophysical mechanism of improved optical properties and bandgap variation in tin-based perovskites, paving the way for their future applications.

One-dimensional (1D) perovskites have garnered significant interest due to their structural stability and self-trapped emission, with Sn-based and Pb-based perovskites being the primary focus. However, the reasons underlying the similarities and differences in the luminescent properties of these two types of perovskites remain unexplored in a systematic manner. Moreover, their properties can be influenced by external factors such as humidity, temperature, and illumination, which may induce subtle lattice expansions or contractions. In this study, we employ density functional theory (DFT) calculations to systematically investigate the similarities and differences in the optical properties and structural stability of 1D perovskites (C4N2H14)PbBr4 and (C4N2H14)SnBr4, as well as the effects of strain on these materials. Our results reveal that the molecular dissociation energy is higher for Pb-based perovskites than for their Sn-based counterparts, and both systems show increasing dissociation energies under greater lattice size. Under strain conditions, both the absorption and emission energies show a regular variation. This trend is more pronounced in Sn-based perovskites, whose optical characteristics are more sensitive to strain, indicating a higher degree of tunability. This enhanced sensitivity is attributed to the more active lone-pair electrons in Sn-based perovskites, inducing stronger lattice distortions and electron-phonon coupling. Furthermore, strain engineering can effectively modify the carrier mobility, optical absorption, and transition dipole moment of 1D perovskite materials, enabling improvements in both phosphor-based luminescence and electroluminescent applications.

Entropy engineering has emerged as a versatile strategy for designing metastable materials with synergistic properties and functionalities. Here, we present a facile solution method that yields a new series of high-entropy metal-halide double perovskites (HE-DPs). Single crystals of HE-DPs with a general formula of Cs2MIMIIICl6 (MI = Ag+, Na+; MIII = In3+, Sb3+, Ho3+, Er3+, Bi3+, Yb3+, Dy3+, or Tb3+) are obtained under mild conditions. Structural and elemental analyses demonstrate the formation of high-entropy single-phase single crystals with five elements occupying the trivalent MIII site. The incorporation of multiple trivalent metal ions in a high-entropy manner appears to drastically improve the ambient stability of double perovskites up to more than three months. The optical bandgap is found to decrease upon alloying at the MIII site. Additionally, the random distribution of lanthanide ions within the crystal structure results in synergic electronic interactions between the lanthanide host and lanthanide-lanthanide ions. The interaction between lanthanides and host induces both broadband emissions and sharp Ln3+ f-f transitions, while the lanthanide-lanthanide proximity leads to efficient NIR-to-visible photon upconversion. Our work underscores the high-entropy strategy for developing robust lanthanide perovskites featuring tailored, multichannel optical properties for advanced lighting, display, and sensing applications.

The large Stokes shifts usually result in open circuit voltage (VOC) reduction, which will affect the photovoltaic performance of the material. Recently, three-dimensional organosulfide-halide perovskites (CYS)PbCl2 and (CYS)PbBr2 [CYS: +NH3(CH2)2S−] have received much attention in the photovoltaic field due to their higher stability and similar photoelectric properties (desirable direct bandgap, band dispersion, and light absorption) than MAPbX3 (X = Cl, Br, and I). Unfortunately, both materials exhibit large Stokes shifts emission. Thus, to be clear about their application prospects in the photovoltaic field, the origin of the large Stoke shift needs to be investigated. Moreover, the bandgaps of (CYS)PbBr2 (2.17 eV) and (CYS)PbCl2 (2.32 eV) are higher than the ideal bandgap value of (0.9–1.6 eV) for photovoltaic materials. Based on density functional theory, this paper explores the cause of large Stokes shifts and further improves the photovoltaic performance of the materials by halogen substitution. The calculation results show that the large Stokes shifts come from defect emission rather than intrinsic self-trapping emission and the I atom substitution can reduce the bandgap [(CYS)PbI2; gap = 1.85 eV] and enhance the optical absorption and carrier migration ability without destroying the direct bandgap. Our research will promote the experimental synthesis of more excellent perovskite photovoltaic materials.

To study the mechanism of tsunami wave forces on round-ended piers and the force calculation method, a series of round-ended piers with different ratios of length to width (L/D, D is the diameter of the semicircle at both ends, L is the rectangular length between two end semicircles) are taken as the research object of this study. Firstly, a series of tsunami waves are experimentally generated over dry-bed and wet-beds with different water depths in a dam-break flume. Secondly, the pressure time histories on the outer sides of the round-ended piers are presented and explored. After that, the characteristics of the resultant force and moment at the pier bottom, the maximum force and moment as well as the force and moment in the quasi-steady stage, are obtained and analyzed successively, to explore the influence of L/D. Furthermore, the influences of L/D to the mechanism of tsunami wave forces on round-ended piers are exhaustively investigated. The study indicates that, with the increase of L/D, almost unaffected pressure time histories on front side, obvious time delay in the impulsive stage and a slight increase in amplitude in the quasi-steady stage on the back side, are observed, accordingly L/D has a significant influence on the generated force and moment on round-ended piers. Finally, the calculation method of the maximum tsunami wave forces on round-ended piers and the corresponding coefficients are provided. This study can contribute to the safety design of round-ended piers in tsunami-prone areas.

Ferroelectric photovoltaic materials have attracted great attention because of their unique photoelectric conversion mechanism, high photo-generated voltage, and adjustable polarization intensity. Traditional ferroelectric oxide perovskites such as BaTiO3, BiFeO3, and Pb(ZrTi)O-3 have attracted much attention but they are not suitable as light absorbing layers in solar cells, due to the large optical bandgap, low light absorption rate, and small photogenerated current. Therefore, it is necessary to seek prominent materials with both ferroelectric and suitable band gaps. Recently, the evidence of ferroelectricity in the typical three-dimensional all-inorganic halide perovskites CsGeX3, with band gaps of 1.6 eV to 2.3 eV has been confirmed. However, the spontaneous polarization of ferroelectric perovskite CsGeX3 is similar to 10 to 20 mu c cm(-2) which is weaker than that of ABO(3) (similar to 26 to 75 mu c cm(-2)). Strain engineering has a significant influence on the properties of semiconductor materials by controlling the lattice scaling and the internal atomic spacing. Hence, in this work, strain engineering is introduced to adjust the ferroelectric polarization and the photoelectric properties of ferroelectric perovskite CsGeBr3. The calculated results show that when the applied compressive strain increases from 0% to -4%, the spontaneous polarization of ferroelectric perovskite CsGeBr3 increases from 14.23 mu c cm(-2) to 51.61 mu c cm(-2), and the band gap reduces from 2.3631 eV to 1.5310 eV. The effective mass of electrons and holes gradually reduces, exciton binding energies decrease from 48 meV to 5 meV, and the optical absorption coefficient is strongly enhanced from 3 x 10(5) cm(-1) to 5 x 10(5) cm(-1) in the visible range. Besides, the power conversion efficiency(PCE) of CsGeBr3 is significantly increased from 16.95% to 26.77%. Therefore, the results indicate that the application of compressive strain can increase the ferroelectric polarization and enhance the original photovoltaic performance of ferroelectric perovskite CsGeBr3. Our theoretical calculations can provide useful insights and beneficial guidance into experimental studies of ferroelectric perovskites in photoelectric applications.

Two-dimensional (2D) metal halide perovskites have garnered significant attention in the field of lightemitting diodes due to their high photoluminescence quantum yield and tunability. In comparison with the widely studied 2D Ruddlesden-Popper (RP) perovskites, the 2D Dion-Jacobson (DJ) double perovskites, which offer higher stability and nontoxicity, have received relatively less attention. In addition, the regulatory effects of halogens on the luminescence mechanisms and performance of 2D DJ double perovskites remain unknown. Utilizing density functional theory, the stability and luminescence properties of 2D DJ double-perovskite (C 6 H 16 N 2 ) 2 AgBi X 8 H 2 O ( X = Cl, Br, I) are effectively modulated through halogen substitution. The findings indicate that the dissociation energy incrementally increases as the halogen changes from Ito Br to Cl, suggesting that the incorporation of lighter halogens enhances structural stability. The minimal self-trapping formation energy (i.e., 0.08 eV) of (C 6 H 16 N 2 ) 2 AgBiI 8 H 2 O facilitates easy detrapment of self-trapped excitons, leading to a tendency toward free exciton luminescence. The self-trapping formation energies of (C 6 H 16 N 2 ) 2 AgBiBr 8 H 2 O and (C 6 H 16 N 2 ) 2 AgBiCl 8 H 2 O are 0.77 eV and 0.96 eV, respectively, indicating substantial self-trapping depths; thus, favoring selftrapped exciton luminescence. In addition, the transition dipole moments of (C 6 H 16 N 2 ) 2 AgBiBr 8 H 2 O and (C 6 H 16 N 2 ) 2 AgBiCl 8 H 2 O are substantially higher than those of (C 6 H 16 N 2 ) 2 AgBiI 8 H 2 O, suggesting that substituting I with Cl and Br enhances the luminous efficiency of 2D DJ double-perovskite (C 6 H 16 N 2 ) 2 AgBi X 8 H 2 O ( X = Cl, Br, I). These results indicate that halogen substitution can not only affect the stability of 2D DJ perovskites but also modulate their luminescent properties. Our research provides theoretical insights for the experimental design of superior luminescent materials.

Two-dimensional Ruddlesden-Popper perovskites have garnered significant attention due to their excellent environmental stability, tunable photophysical properties, and other advantageous characteristics. Although two-dimensional perovskites have been extensively studied in the field of photoluminescence, their application in photovoltaics has been limited due to high exciton-binding energy. Recently, another Ruddlesden-Popper perovskite Cs2Pb(SCN)2Br2 has been synthesized. Compared to most twodimensional perovskites, Cs2Pb(SCN)2Br2 boasts the advantages of low exciton-binding energy and a narrow optical band gap. To explore the potential of two-dimensional perovskites in photovoltaic applications, an all-inorganic two-dimensional heterojunction Cs2Pb(SCN)2Br2/MoS2 was investigated using first-principles calculations based on density-functional theory (DFT). Our calculation results demonstrate that the heterojunction exhibits significantly enhanced optical absorption properties and carrier mobility compared to Cs2Pb(SCN)2Br2 material. The heterojunction features a typical type-II band alignment, making it highly suitable for photovoltaic applications such as solar cells. We also applied a longitudinal electric field to the heterojunction in calculations, thereby regulating its band alignment. The calculation results reveal that the type-II band alignment of the heterojunction can be transformed into type-I and type-III alignments. These findings significantly expand the application potential of the heterojunction in electronic and optoelectronic devices.