The concept of multiscale fibrous reinforcements in cementitious matrices is characterized by a wide range of scales from distributed nanomaterials and chopped short fibers to continuous fibrous reinforcements. Based on fibrous reinforcements at multiple scales, this study elaborately optimizes mechanical behavior by tailoring the types and volume fraction of fibers and develops a cementitious composite, flexible ultra-high performance reinforced cementitious composite (FHPRC), with 160 MPa compressive strength, 36 MPa tensile strength, over 1% ultimate tensile strain, less than 0.1 mm crack width, and significant post-yield stiffness. FHPRC combines the superior strength and durability of ultra-high performance concrete (UHPC) with the high ductility and crack control capacity of engineered cementitious composite. We demonstrated the effectiveness of the material design strategy through experimental and numerical examinations. The effects of the types of short fibers (steel with a designed length of 13 mm and glass with a length of 50 mm), fiber-reinforced polymers (FRPs) (carbon and glass), and textile configuration on the flexural behavior were analyzed. To capture their flexural behavior, several numerical models have been developed to optimize FHPRCs. Furthermore, the layered shell finite element model (FEM) based on the smeared crack approach considerably simplifies the numerical effort required to simulate intense matrix cracking. However, no realistic constitutive model for any composite containing one or more reinforcing fibers for layered shell FEMs has been developed. Hence, an equivalent constitutive model for layered shells was established to analyze the flexural behavior of FHPRCs. The model proved that the combination of UHPC and carbon FRP textiles yielded a superior composite. The research results provide valuable insights into the evolving field of advanced construction materials and engineering.
Biology has been a brilliant teacher and a precious textbook to man-made construction for thousands of years, because it allows one to learn and be inspired by nature's remarkable and efficient structural systems. However, the emerging biomimetic studies have been of increasing interest for civil engineering design only in the past two decades. Bridge design is one of aspects on structural engineering of biomimetics that offers an enormous potential for inspiration in various aspects, such as the geometry, structure, mechanism, energy use and the intelligence. Recently built bridges and design proposals in which biological systems have produced a range of inspiration are reviewed in this paper. Multidisciplinary cooperation is discussed for the implementation of bio-inspired methods in future design. A case study about using bio-inspired strategy is trying to present a problem-solving approach, yet further cooperation is still needed to utilize biomimetic studies for design inspiration. This paper aims to call a close multidisciplinary collaboration that promotes engineers to build more sustainable and smart structural systems for bridges in the 21st century.
In quasi-static tests of large-scale structural columns and/or columns under large axial loads, the lateral friction force between the column and the loading system can become a significant problem: they may cause considerable deviation between the measured lateral force and the actual reaction force of the column, especially under large axial compression load. Many researchers have come up with different methods to reduce or eliminate the influence of such friction force. In this article, previous treatments on the lateral friction force in quasi-static tests are first discussed. A shear force measurement device, for accurate measurement of the friction force, is then presented and calibrated. Based on the friction forces measured by the device in real tests, a simple model is proposed to predict the lateral friction force in quasi-static tests. Using the model, the measured lateral force in such tests can be corrected to obtain the actual reaction force of the column when a friction measurement device is absent. The proposed model and the correction method are then validated using results from several previous tests.
<title>Abstract</title> <bold>Ethnopharmacological Relevance:</bold> Zuo Gui Wan (ZGW), a traditional Chinese medicine (TCM) formula, shows potential for treating postmenopausal osteoporosis (PMOP), combining traditional herbal knowledge with modern scientific validation. <bold>Background:</bold> Postmenopausal osteoporosis (PMOP) is a metabolic bone disorder caused by estrogen deficiency, leading to decreased bone mass and increased fracture risk. ZGW has shown promise in managing PMOP, but its active metabolites and mechanisms remain unclear. <bold>Methods:</bold> Ovariectomized (OVX) rats were used to model osteoporosis. ZGW's efficacy was evaluated through micro-CT, HE staining, and serum ELISA. Active metabolites in serum were identified by UPLC-MS/MS. A "botanical drug-metabolite-target-disease" network was built using network analysis. Pathway enrichment was performed using GO and KEGG in R. Molecular docking of key metabolites and targets was conducted using AutoDock Vina and PyMOL. In vitro assays, including MTT, ALP, Alizarin Red S staining, PCR, and Western blotting, validated osteogenic effects. <bold>Results:</bold> ZGW improved bone microstructure and serum bone metabolism in OVX rats. UPLC-MS/MS identified 209 metabolites, with 20 transferring into the serum. PPI analysis revealed 144 key targets, and molecular docking showed strong binding between active metabolites (e.g., Remycin A, Farnesecin) and their targets, such as ALB and EGFR. GO and KEGG analyses identified pathways like HIF-1, estrogen signaling, and PI3K-Akt. In vitro, ZGW activated these pathways, enhancing osteogenic marker expression and promoting osteoblast proliferation and differentiation. <bold>Conclusion:</bold> ZGW treats PMOP through multiple mechanisms involving active metabolites, targets, and pathways. It restores normal gene expression and modulates pathways such as HIF-1 and PI3K-Akt, while also inhibiting inflammation. This study highlights the power of combining UPLC-MS/MS with network analysis for exploring TCM formulations in PMOP treatment.
In RC buildings, the unexpected sudden failure of a corner column is more likely to cause severe progressive collapse than the failure of an interior column or a side column due to the relatively weak tie force from the surrounding elements. Effective strengthening methods can improve the progressive collapse resistance of these structures. Fiber-reinforced polymer (FRP) has been widely used to retrofit RC structures due to its high strength, light weight, and corrosion resistance. In this study, the progressive collapse behaviors of glass FRP (GFRP)–strengthened RC beam–slab subassemblages under corner column removal were investigated. First, a quasi-static experimental test was adopted to study the progressive collapse resistance of the beam–slab subassemblages, including a control specimen and strengthened specimens. Two techniques applying externally bonded GFRP laminates and near-surface-mounted (NSM) GFRP bars were adopted to strengthen the subassemblages. The influences of the strengthening schemes on the behavior of the tested specimens were studied by comparing all the test results. The experimental results demonstrate that this strengthening technology can enhance the progressive collapse resistance of RC beam–slab structures. Finite-element (FE) analysis of the progressive collapse resistance of the beam–slab subassemblages was also conducted using the software package MSC Marc. The numerical model can predict the progressive collapse resistance of the subassemblages. In addition, the calculated results were used to better understand the stress distribution of the GFRP in a corner column–removal scenario.
No abstract is provided for this article.
Wet-bonding is a technique of connecting fiber reinforced polymer (FRP) profile and cast-in-place concrete, which is characterized by the simultaneous hardening of concrete and adhesive. The mechanical properties of wet-bonding interface have been investigated by researchers, but none of them considers the influence of lateral confinement which is commonly present in structures. The insufficient knowledge on wet-bonding consequently hinders its application in FRP-concrete hybrid structures. To this end, this paper investigates the bond properties of wet-bonding interface in confined concrete through pullout and pushout tests. Test results indicate that the interfacial behavior of wet-bonding interface can be divided into three stages. In the first stage, the interfacial resistance comes from the chemical bond of adhesive, and the lateral confinement is hardly activated. This stage comes to an end when the interface between adhesive and concrete fails. In the second and third stage, the interfacial resistance is mainly contributed by the friction between fractured surfaces of adhesive and concrete. The relative movement of fractured surfaces which are microscopically rough induces vertical movement and then activates the lateral confinement, resulting in lateral pressure and tangential friction. The significant friction behavior further damages the FRP-adhesive interface, leading to the final delamination of adhesive from the FRP plate. Based on the above force-transfer mechanism, a bond stress-slip model depending on the lateral pressure is developed. This interfacial model is implemented into Abaqus and its effectiveness is verified by comparing with test results.
To improve construction efficiency in offshore engineering and extend service life of offshore platforms, a novel bamboo-raft-type floating structure (BRT-FS) assembled by FRP reinforced concrete tubes is proposed. It comprises four fundamental components: concrete tube, carbon fiber-reinforced polymer (CFRP) cable, holding beam, and bellow. This paper presents the structure system and structure design of BRT-FS. Separating load-bearing and buoyant functions ensures structural safety and ease of design. It has broad application perspectives in offshore construction due to its high corrosion resistance, designability, construction efficiency, and low crack control requirement. Furthermore, to obtain the operation conditions of BRT-FS, the mechanical performance is analyzed from two levels, which are hydroelastic analysis and structural analysis. Hydroelastic analysis is conducted under different wave directions, wave periods, water depths, and structural dimensions using a new finite element-boundary element (FE-BE) method. In a specify study case, a sensitive period around 11 s for head sea, around 7 s for oblique wave, around 5 s for beam sea are noted. The hydroelastic response is not significantly affected by water depth or transverse dimension. Structural analysis indicates that the structure can work in clam harbour sea with breakwater protection. Even after concrete tubes crack in higher waves, this new structure can still float with the inside bellows in theory. These preliminary findings confirm the feasibility of this novel structure. Structural details such as tube-tube joints, tube-beam joints, CFRP cable anchorages, and other connections will be further designed and tested in the future.
FRP strips, which are light-weight, high-strength and anticorrosion, are crossed and woven to form a flexible plane FRP web. The web can acquire the adequate stiffness and bearing capacity in the results of the tension applied by tendons in out-plane direction. Then the tensed FRP web can act as roof structures. It is an innovative structure for the FRP application for large-span buildings. In this paper, the basic configuration of FRP woven web structure is introduced, and its structural characteristic is investigated. Three key states of a simple FRP woven web structure from the construction to the service, including the initial prestressed state, the out-of-plane tensioned state and the service loading state, are analyzed. The response of strips within a simple FRP woven web structure is finally examined, which confirms the feasibility of the structure form.
The three dimensional (3D) printing technology has undergone rapid development in the last few years and it is now possible to print engineering structures. This paper presents a study of the mechanical behavior of 3D printed structures using cementitious powder. Microscopic observation reveals that the 3D printed products have a layered orthotropic microstructure, in which each layer consists of parallel strips. Compression and flexural tests were conducted to determine the mechanical properties and failure characteristics of such materials. The test results confirmed that the 3D printed structures are laminated with apparent orthotropy. Based on the experimental results, a stress–strain relationship and a failure criterion based on the maximum stress criterion for orthotropic materials are proposed for the structures of 3D printed material. Finally, a finite element analysis was conducted for a 3D printed shell structure, which shows that the printing direction has a significant influence on the load bearing capacity of the structure.
Cellular materials, widely found in engineered and natural systems, are highly dependent on their geometric arrangement. A nonuniform arrangement could lead to a significant variation of mechanical properties while bringing challenges to material design. Here, this proof-of-concept study demonstrates a machine-learning-based framework with the capability of accelerated characterization and pattern generation, which also opens new avenues for the programmability of function at the system level.
No abstract is provided for this article.
9月28日 晴 现代社会总是以国民幸福感来评价一个国家是否真正的发达，尽管这个衡量标准比以GDP金钱作为衡量标准要“高尚”得多，但我始终觉得，一个人乃至一个国家的幸福感都不是别人给得了的，自始至终，是否幸福只有自己给的了自己，
No abstract is provided for this article.
Against the backdrop of high-quality development in the new era, the expanding scale of Chinese college graduates, coupled with economic slowdown and industrial restructuring, has led to structural employment pressure. Flexible employment, though a key transitional choice for new graduates, lacks a sound supporting system. This paper focuses on college students' employment policies, screening 18 authoritative documents via keywords "college students," "employment," and "policies," and categorizes them into four types: policy issue analysis, orientation & countermeasures, situation & evolution, and research in special periods/new perspectives. A policy focus, government-market roles, and research methods. Existing studies contribute significantly through interdisciplinary frameworks, scientific methods, structural problem diagnosis, and multi-level countermeasures. However, they have shortcomings: insufficient discussion on adapting to emerging occupations, lack of group need subdivision, over-reliance on Western models disconnected from China's reality, and inadequate policy dynamic adjustment and long-term evaluation. Accordingly, it proposes research directions on labor relations identification, skill training, social security connection, and inter-departmental collaboration in college students' gig and flexible employment, designing a framework including literature review, policy analysis, and mixed research. Future research should consider emerging technologies, regional differences, and long-term tracking, with theoretical significance in enriching policy research and promoting interdisciplinary integration, and practical significance in guiding policy optimization, supporting employment/entrepreneurship, and boosting social harmony.
With advancements in material properties and reduced costs, carbon fibre reinforced polymer (CFRP) cables are gaining popularity in engineering applications due to their superior strength-to-mass ratio and durability. However, the tensile strength of large-scale parallel CFRP cables remains a critical issue, warranting further research and engineering expertise. To address this issue, this paper proposes a method to rapidly predict and adaptively correct the tensile strength of large-scale parallel CFRP cables using multi-source experimental data and an integrated approach that incorporates Monte Carlo simulations, Neural Network algorithms, and Genetic algorithms. This comprehensive method takes into account the influence of various factors including small-scale material strength and its coefficient of variation, cable length, the number of parallel wires, installation errors, and anchorage errors. Validated by reported experimental data, the method demonstrates its effectiveness in accurately predicting the tensile strength of parallel CFRP cables. Moreover, a design method for large-scale parallel CFRP cables is proposed based on the reliability theory. Lastly, the efficiency and effectiveness of the proposed method are validated through the design and optimization of a cable-stayed bridge featuring a main span of 1984 m, utilising both parallel steel and CFRP cables.
