To optimize space and maintain structural integrity, web openings are often introduced to accommodate building services, limiting their applications. Also, such stainless-steel members serving as I-beams are frequently susceptible to experiencing the localized loading (patch loading) induced by moving load. However, there is a lack of design provisions for the localized-loading resistance prediction of such stainless-steel I-beams with web openings under localized loading. Building on previous experimental work by the authors, this work addresses this gap by performing a comprehensive numerical analysis aimed at developing new design provisions for the localized-loading resistance of such I-beams. The novelty of this work lies in the development of new semi-empirical design equations that incorporate key geometric parameters influencing the strength of perforated stainless steel members. Two commonly used stainless steel (austenitic and duplex) were examined in this work. An advanced numerical model was developed, and the validation process involved a detailed comparison between the numerical results and corresponding experimental data. Following this validation, the same FE modelling approach was employed to perform an extensive parametric study. A total of 2128 numerical findings were reported, evaluating the effects of localized-loading width ratios, web aspect ratios, web slenderness, hole size ratios and initial geometrical deformations. The findings from the parametric analysis were further used to assess the accuracy of the existing design provisions. The comparison highlighted that the existing provisions could not accurately predict the localized-loading resistance of such I-beams. To address this limitation, new simplified design provisions were proposed, and the modified coefficients were applied to the existing design provisions. The comparison findings demonstrated that the new provisions proposed in this work could provide accurate and reliable predictions, offering a significant improvement over the existing design provision.

Cold-formed steel (CFS) channels with edge-stiffened web holes are widely used as flooring joists and bearers in industrial buildings and their flanges are fastened in most cases. This prevents the rotation of flanges and increases their web crippling capacity. In the literature, no information is available on the web crippling capacity of such fastened CFS channels with edge-stiffened web holes. This study presents the results of 36 new web crippling tests which were conducted on CFS channels with edge-stiffened web holes under fastened support subjected to two-flange loading. For comparison, specimens with no hole and un-stiffened web holes were also tested. Finite element (FE) models were then developed and validated against the experimental results. Using the validated FE models, an extensive parametric study involving 912 FE models was conducted. In the parametric study, web thickness, size of the web holes, length of bearing plate and length of edge stiffener were varied. Test results indicated that the specimens with fastened flanges have higher ultimate capacity than those with unfastened flanges. For the case of fastened flanges, the web crippling capacity increased by 71% and 33% for the end-two-flange (ETF) and interior-two-flange (ITF) loading, respectively. Finally, the test results were compared with the design strengths predicted by the proposed equations of Uzzaman et al. (2020) for channels with web holes, and against the design equations of current design standards (American Iron and Steel Institute (AISI) (2016), Australian and New Zealand Standards (AS/NZS) (2018), and European Standard (EC3) (2006)) for plain channels. Upon comparison, it was found that the web crippling capacity reduction factor proposed by Uzzaman?s equations (2020) gave close predictions to the test results for CFS channels with edge-stiffened web holes.

Recently, a new generation of cold-formed steel (CFS) channel section with edge-stiffened web holes has been developed by industry in New Zealand. However, no research has been reported in the literature to investigate the axial capacity of back-to-back channels with edge-stiffened web holes. This paper presents a total of 73 new results comprising 29 compression tests and 44 finite element analyses (FEA) on axial capacity of such back-to-back CFS channels. The results show that for back-to-back channels with seven edge-stiffened holes, the axial capacity increased by 19.2%, compared to plain channels without web holes. A non-linear finite element (FE) model was developed and validated against the test results. The validated FE model was used to conduct a parametric study involving 44 FE models. Finely, the tests results were compared with the design strengths calculated from the AISI and AS/NZ standards and from the proposed design equations of Moen and Schafer. From the comparison results, it was found that the AISI and AS/NZ design strengths are only 9% conservative to the test results for plain channels without web holes. While Moen and Schafer equations are conservative by 13% and 47% for axial capacity of CFS back-to-back channels with un-stiffened and edge-stiffened web holes, respectively.

This paper presents a finite element analysis of cold-formed stainless steel channels with circular web holes, subjected to end-one-flange loading condition. The material properties of stainless steel types EN 1.4509 (Ferritic), EN 1.4462 (Duplex) and EN 1.4301 (Austenitic) were taken from the literature. To investigate the effect of web hole size, web hole location and bearing length on the web crippling strength of such sections, a parametric study involving a total of 1728 FE models was performed. The parametric study results were used to propose new web crippling strength equations and strength reduction factor equations which outperformed the equations of American Society of Civil Engineers Specification (ASCE 8–02), American Iron and Steel Institute Specification and Australia/New Zealand Standard (AISI&AS/NZS) and Lian et al (2016). A reliability analysis was then performed, which showed that the proposed design equations can closely predict the web crippling strength of cold-formed stainless steel channels with and without web holes under end-one-flange loading condition.

以工程管理专业的人才培养模式适应建设行业的应用型人才培养规格的要求.针对"建筑结构"课程实验教学的需要,研究虚拟仿真技术在课程教学改革过程中应用的优势和实现途径,开设在线实验课程平台,虚实结合,优化实验课程体系,提升实验教学质量.从而也提高了学生的创新能力和综合实践能力,为全国同类院校工程管理专业实践课程改革建设提供思路和参考.

From the current teaching practices in civil engineering at Jimei University,a structural test platform is introduced for research universities,teaching-research universities,and teaching universities in China.Suggestions for the planning and construction of a pseudo-dynamic testing platform for MDOF(Multiple Degrees-of-Freedom) structures are put forward;these include the basic teaching loading test system for structural mechanics,the pseudo-dynamic testing of MDOF structures,and a planning index for architectural design,structural design,and equipment design.In addition,suggestions are made with regard to educational reform by means of testing platforms,including faculty construction using testing platforms and the optimal development of testing platforms,undergraduate learning,and scientific research.The results of this study can be applied in the planning and construction of pseudo-dynamic testing of MDOF structures in teaching universities.New methods of educational reform are outlined

The purpose of this paper is to investigate the effect of electroosmosis technology on durability of filtering concrete.The microstructures were compared by SEM.The ability to resist chloride ion penetration wase studied by chloride ion penetration test.The experimental results indicate that electroosmosis technology can further the filtering velocity markedly,reduce the water cement ratio of solidification and improve interfacial microstructures significantly.The compactness and ability to resist chloride ion penetration of filtering concrete would be greatly improved after electroosmosis.

Main influencing factors of electroosmosis such as voltage,types of cement and retarder are analyzed in this paper.The experimental results indicate that ZnO retarder can increase the filtering velocity markedly,which ensures the strength and durability of filtering concrete effectively.Relationship between filtering capacity and time is then deduced.A design method for mix proportions,which can be used in real engineering,is proposed.

By using high content of MgO expansion agent which produces self-stress,the problem of interface disengaging is solved.Experimental research on using MgO expansion agent self-stressing concrete-filled steel tube is carried out.The experimental results indicate that the characteristic of delayed expansion of MgO expansion agent can ensure the expansive deformation,keep the self-stress stable for a long time.MgO expansion agent can produce high value of self stress by restraint of steel tube,and thus enhance the ultimate strength of concrete core subjected to axial compressive loading.Meanwhile,the self-stress can further the compaction rate of concrete core.

Experimental research on using MgO expansion agent self-stressing concrete-filled steel tube subjected to axial compressive loading is carried out.The effect of initial self-stress tube on the ultimate strength and deformation capacity is discussed.The experimental results indicate that the self-stress can make concrete core compressed in three directions by restraint of steel tube,enhance the ultimate strength of composite columns subjected to axial compressive loading,delay the expansion of crack of concrete core during elastic-plastic stage and increase the tangent elastic modulus of concrete core.Meanwhile,the self-stress can make the concrete core more compact and resolve the problem of interface disengaging successfully so that it can ensure the concrete core and steel tube act together in resisting the axial load.

本文旨在通过组合柱的轴压试验研究模网钢管混凝土组合柱轴心受压时的基本性能。实验证明模网钢管混凝土组合柱具有卓越的工作性能、良好的强度和变形能力。分析了建筑模网、MgO膨胀剂等因素对组合柱强度和延性的影响。最后提出了模网钢管混凝土组合柱轴压承载力的简化计算公式。

The purpose of writing this paper is to investigate the fundamental characteristics of concrete columns reinforced with concrete-filled steel tube subjected to axial compressive loading.To accomplish this task,8 specimens are tested.The results from the experimental tests indicate that composite columns can produce higher load-bearing capacity and relatively ideal ductility.The effects of the parameters such as the steel proportion in the concrete-filled steel tubes and the volumetric ratio of transverse ties(ρ) on the strength and ductility of these composite columns are analyzed.And the simplified calculation formulas for predicting the ultimate strength of the composite section are proposed.

In order to realize the recycle use of concrete,the concept of concrete designed by the constituents of cement raw material(CCRM concrete for short) is put forward and the mix design method of this concrete is provided.In the mix design,sand percentage is divided into two parts,nature sand percentage and manufactured limestone sand percentage,and then the mix design of concrete is contacted with the three ratios of cement clinker,which make the oxide constituents of concrete to be similar to those of the cement raw material.After the concrete is abandoned,it can be directly used as cement raw material but not need or just need little materials to adjust the constituents.The experiments show that the workability of the CCRM concrete is lower than that of the corresponding normal concrete,but its mechanical properties are all better;the ratio of the abandoned CCRM concrete is similar to that of the cement raw material which has been designed before the concrete design.The concrete designed by the constituents of cement raw material resolves the problem of the recycle use of the concrete,and at the same time reduces the excessive exploitation of natural resources and the air pollution.

A new type of composite construction——concrete filled steel tube with construction formwork is formed by using the principle of process engineering of materials to optimize the factors of concrete.High water-cement ratio during construction and low water-cement ratio during solidification are realized by using electroosmosis technology to change the process of concrete construction.The experimental results indicate that concrete filled steel tube with construction formwork has excellent work performance,high strength and good deformation capacity.

The purpose of this paper is to solve the problem of high water cement ratio during construction and low water cement ratio during solidification.Utilizing the electric double layer produced by hydration of cement to gather in superfluous water at negative electrode and reduce the water cement ratio of solidification by using electroosmosis technology.The experimental results indicate that electroosmosis technology can further the filtering velocity markedly,increase the compressive strength of concrete significantly and have finer economical efficiency.Electroosmosis technology can solve the problem of high water cement ratio during construction and low water cement ratio during solidification effectively so that have expansive application prospect.

A green concrete construction technology-filtering concrete is studied.Filtering concrete is low bleeding concrete with high water cement ratio and high fluidity.High water cement ratio during construction and low water cement ratio during solidification are realized.Factors affecting the filtering and fluidity of filtering concrete such as water cement ratio,quantity of cement and quantity of fly ash are analyzed.The experimental results indicate that the compressive strength of concrete can be increased significantly after filtering.