Existing resilient steel beam-column joints adopt a double-sided opening mechanism that resulted in slab damage during earthquakes. To address this, a novel single-sided beam-column joint with tension-compression bolts (TCBs) and a buckling-restrained flange cover plate (BFCP) was proposed, which features an opening-closing mechanism at the bottom flange. A theoretical hysteretic model of the joint was first established, and this was followed by conducting quasistatic tests of four full-scale samples to evaluate its cyclic behavior. The effects of the key parameters, including the presence of a BFCP, the TCB preload level, and the core plate strength, on the cyclic behavior of the joint were examined. A finite-element model (FEM) was subsequently developed and validated against the test results. The validated FEM was then employed to verify the theoretical hysteretic model and to investigate the influence of the top flange connection plates (TFCPs) on the cyclic behavior. The results indicate that the joint achieves the intended single-sided opening-closing mechanism, with reduced residual deformation and enhanced energy dissipation. The addition of a BFCP increased energy dissipation by 77.7 % but increased residual deformation by 29.5 %; the absence of TCB preloading led to greater hysteresis and increased residual deformation by 29.5 %; and the decrease in the core plate strength reduced peak moment but improved the self-centering performance. The form of the TFCP influenced the cyclic behavior of the joint by altering the location of its rotation center, and an overly thin TFCP may yield during loading and consequently reduce the self-centering performance of the joint.

This study presents a novel steel frame infilled with double skin composite wall (SFDSCW) system designed to enhance the seismic performance of steel moment-resisting frames while offering advantages in constructability and prefabrication. A full-scale SFDSCW specimen was tested under cyclic loads to investigate its failure modes, hysteretic behavior, energy dissipation capacity, and stiffness degradation. The experimental results demonstrated that the specimen achieved ultimate story drift ratios of 1/58 and 1/53 in the positive and negative loading directions, with a mean displacement ductility coefficient of 2.13. The specimen exhibited a dual-resistance mechanism, in which structural damage progressively transferred from the high-stiffness DSCW to the steel frame. The DSCW initially resisted approximately 68% of the total lateral shear force, while its contribution decreased to 38% at the ultimate state. A hybrid numerical model incorporating fiber-based beam-column elements and multi-layer shell elements was developed and validated against the experimental results. Parametric analyses identified the steel beam dimensions and the DSCW shear-span ratio as the most critical factors governing the initial stiffness, load-carrying capacity, and energy dissipation capacity of the system. Finally, theoretical design equations for load-carrying capacity and elastic lateral stiffness were derived.

To improve the seismic performance and shear capacity of joints between steel beams and reinforced concrete columns (RCSs), this paper proposes prefabricated concrete column-steel beam joints connected by tie bars. Five joint members were designed and fabricated for the proposed static tests, and the damage pattern, hysteresis performance, and load-carrying capacity of each specimen were investigated, with the diameter of the tensile reinforcement and the relative position of the tensile reinforcement and the flange of the steel beam as the main parameters. The test results show that the hysteresis curve shape of each specimen is fuller, the ductility coefficient is between 3.30 and 4.62, and the joints have a good capacity for plastic deformation. The bearing capacity of the joints increased as the diameter of the tie bars increased; the bearing capacity and elasticity of the joints decreased when the tie bars were arranged inside the steel beam flange. In this paper, three existing shear capacity calculation methods for RCS joints are compared and evaluated, and combined with the experimental results, a finite element calculation model for this kind of joint specimen is established and a shear capacity calculation formula for prefabricated concrete column-tension reinforcement connection joints is proposed. The new calculation method agrees with the test values and can be used to design tension reinforcement connection joints for practical engineering applications.

Beam-column connections are essential to the seismic behavior of precast concrete frames. This paper introduces a novel steel-concrete composite beam-column joint for precast concrete frames. The design purpose is to obtain a more efficient and convenient joint connection with superior seismic performance. Four full-size joints were designed and fabricated for the cyclic loading test, including three weak joints (WJs) and one strong joint (SJ). The test variables were the width of the face bearing plates (FBPs), the thickness of the steel beam flanges, and the height of the steel band plates (SBPs). This test investigated the joints' seismic performance and stress transfer mechanism. The test results indicated that these joints have favorable ductility and seismic performance. The addition of the steel skeleton enhanced the integrity and shear strength of the joints. The increase in the FBP width improves the bearing capacity of the joint. The decrease in the flange thickness of the steel beam changes the failure mode of the joint. The increase in the SBP height delays the stiffness degradation rate of the joint. The composition of the joint shear strength is discussed, and the applicability of the existing shear capacity calculation model to the joints in this paper is checked. The finite element simulation of joints was performed, and the results aligned well with the test results. Parameter analysis further investigated how the thickness of FBPs, the axial compression ratio, and the column reinforcement ratio affect the seismic performance of the joints.

The use of recycled coarse aggregates (RCA) in concrete is currently recognized for its positive impact on reducing environmental hazards and promoting sustainable development, a trend observed worldwide. However, despite these benefits, RCA’s disadvantages on concrete properties have led to limited attention and usage. Developing an optimal RCA mixture design in the laboratory is time-consuming and can cause construction delays. In this study, various artificial intelligence models were employed, including the group method of data handling neural network (GMDH-NN), combinatorial method of group method of data handling (GMDH-Combi), and multiple linear regression method (MLR), to address the challenge of estimating the compressive strength of RCA concrete. Performance evaluation of these models utilized metrics such as the correlation coefficient (R), mean square error (MSE), mean absolute error (MAE), and square root mean square error (RMSE). The GMDH-Combi model demonstrated superior performance compared to other methods. In the testing subsets, it achieved R, MSE, RMSE, and MAPE values of 0.89, 53.56, 7.32, and 13.61, respectively. In the training subsets, the model showed R, MSE, RMSE, and MAPE values of 0.87, 53.77, 7.33, and 12.77, respectively.

Beam-column joints are a crucial core part of prefabricated concrete structures. This paper presents a novel prefabricated steel-concrete composite beam-column joint. The design goal was to achieve high ductility and good energy dissipation capacity while improving construction efficiency. Five full-scale fabricated concrete mid-joints were designed and manufactured, including four tensile reinforcement joints (TRJs) and one inner diaphragm joint (IDJ). Tests were conducted to determine the effects of wrapped steel tube thickness, reinforcement plate settings, and typical failure modes of internal connection measures. Seismic performance was analyzed. The results showed that the joints exhibited excellent seismic performance. The increases in the wrapped steel tube thickness cause a failure mode to develop from the joint area’s bending failure to the beam-end bending failure. The joints can provide efficient and reliable connection methods for engineers to design prefabricated concrete structures. The numerical simulation was performed on TRJs based on the experiment, which agreed with the test regarding hysteretic response and typical failure modes. Parameter analysis was used to study the effects of the wrapped steel tube’s extension height, the tensile reinforcement’s diameter, and the layout measures.

Due to the limited application of the natural river sand in China, recycled sand (RS) has been considered as an important replacement of natural sand in sustainable construction. The morphology of recycled sand is critical to its effective application in mortar and concrete. An environmentally friendly approach is introduced in this work to improve the morphology of recycled sand during its crushing process. This paper presents a newly developed image acquisition device, which obtained 25,328 RS images to use as a dataset for the construction of a segmentation model based on deep learning technology with an automatic segmentation of RS characteristics. Evaluation indices including accuracy (ACC), Recall, intersection over union (IoU), and F1-score index are reaching up to 99.8%, 88.1%, 84.9% and 84.3%, respectively. RS morphological characteristics including the flat and elongation ratio (FER), angularity index (AI), roundness (R) are automatically extracted by the proposed model, and the predicted results agreed well with the experimental ones. Finally, the effect of FER of RS on mortar’s mechanical properties is investigated by a series of experiments. Results reveal that the flowability, flexural strength and compressive strength of mortar decreased invariably with the lower FER of sand.

In recent years, recycled aggregate concrete (RAC) has been used as a suitable solution to solve the problems related to the disposal of construction waste and contribute to sustainable environmental development. However, RAC has defects such as low modulus of elasticity and low compressive bearing capacity, which limits the use of RAC only in non-structural cases. Using composite columns in construction is an excellent way to overcome this limitation. Thus, increasing the use of these columns makes it possible to predict their compressive strength to assist in their design. As part of this study, several artificial intelligence algorithms, including the ANN, the GEP, and the MLR, have been analyzed to predict the compressive strength of recycled aggregate concrete-filled circular steel tubes (RACFCST). A total number of 103 valid experimental data were collected from earlier investigations and the models were trained by 75% of them; the rest were considered for testing. RACFCST's compressive strength was investigated as the target of the models. In addition, the proposed models were evaluated by contrasting them to code equations like ACI, Eurocode, AIJ and DL/T to determine whether or not they were valid and whether or not they were predictable. The findings of this research suggested that all three models utilized in this investigation produced accurate predictions when compared to the results of the experiments. As a consequence, the values of R2 in all three models were greater than 0.9, but the ANN model, which had an R2 value of 0.993, demonstrated the highest level of accuracy. While among design code equations, DL/T with R2 equal to 0.957 showed the best performance in predicting the results.

A double-skin composite wall (DSCW) with innovative L-shaped connectors was proposed, which can be simply constructed and quickly assembled to promote the development of a prefabricated steel structure. To further examine the seismic capacity of the novel DSCW, five DSCWs were designed and fabricated, each with a low shear-span ratio. The testing parameters include the welding spacing, distance between connectors, and the width-to-thickness ratio of the wall-to-steel faceplate. The failure mode of each DSCW specimen was observed, while determining the load-carrying capacity, the hysteretic curve, the skeleton curve, and the displacement ductility coefficient. Moreover, the distribution and development of the boundary column strains, steel faceplate strains, and L-shaped connector strains were researched. The test results showed that the DSCWs with a low shear-span ratio had excellent load-carrying capacity and ductility, and all specimens experienced flexural-shear failure. Decreasing the welding spacing of L-shaped connectors or reducing the distance between L-shaped connectors can enhance the capacity of energy dissipation and ductility, but such a distance reduction has a slight effect on the shear strength. When the thickness of the steel faceplate on different specimens is the same, the load-carrying capacity of the DSCW specimen obviously improves as the width-to-thickness ratio of the wall-to-steel faceplate increases. Finally, shear strength calculation formulas of the novel DSCW under the low shear-span ratio were established.

在新时期课程思教育改革的背景下，工程结构抗震是土木工程本科教学的重点。如何坚持以学生为中心，立德树人，教育教学过程中融入思政教育，并激发学生学习工程结构抗震的兴趣，实现以能力为导向的教学目标，探索相应的教学改革和教学设计是十分必要和迫切的。为此，本文以特定章节为例，进行了详细的教学设计，以期将知识传授、能力培养、思想引领融入课程教学的全过程，为社会主义建设培养德才兼备、具有工匠精神、敬业精神、科学精神高素质土木人才。

为改善型钢与混凝土之间的粘结性能和协同工作能力,将花纹钢板引入型钢混凝土组合结构中,利用花纹钢板的凸起花纹来提高接触面的粘结强度.制作了 10个花纹工字型钢混凝土试件和1个普通型钢混凝土试件进行推出试验,研究花纹高度、花纹钢板设置位置和横向配箍率三个因素对粘结滑移性能的影响.对试件的破坏过程、破坏机理以及加载端荷载-滑移曲线、型钢应变沿其锚固长度的分布曲线进行了分析,回归拟合出各特征粘结强度的计算公式.试验结果表明,将花纹钢板引入型钢混凝土结构中,可显著提高型钢与混凝土接触面的粘结强度,同时试件的极限粘结强度和残余粘结强度随花纹高度和配箍率的增大而增大;花纹钢板设置在型钢不同位置时,对粘结强度的贡献不同,其中设置在型钢外翼缘对粘结强度的提高最为有利,设置在型钢内翼缘次之,设置在型钢腹板最小;建立的特征粘结强度计算公式能够较好地预测试验结果.

Global copper slag (CS) emissions reached 57.2 million tons in 2021. Despite the increasing reuse of CS, the treatment of CS is still dominated by landfill so far, which not only occupies land resources but also causes damage to the environment. The application of CS to cement-based materials (CBMs) is one of the main approaches to its comprehensive utilization and has important economic and social implications. This article reviews the physicochemical properties, activity excitation, and heavy metal leaching properties of CS and summarizes the effect of CS on the working properties, mechanical properties, and durability of CBMs. At the end of the article, the existing problems in the research are analyzed, and the development trend is proposed, which provides technical guidance and reference for further research and application of CS in CBMs in the future.

In order to investigate the bond slip behavior of checkered c-shaped steel encased concrete composite beams with braces under load, a total of 12 checkered c-shaped steel encased concrete push-out specimens were tested based on the orthogonal design method, with the consideration of the bonding performance of steel and concrete affected by the height of the patterned steel plates, the concrete strength grade, the spacing of the brace, the width of the cross-section, and the flange form. Each specimen's relevant data, including the load-slip curves of the steel plate, the strain of the steel plate distributed along the longitudinal direction, and the characteristic bond strengths were all analyzed during the test. The experimental results show that the effect of increasing the pattern height is the most beneficial way to improve bond performance; the characteristic bond strength increases with the increase of the concrete strength and decreases with the increase of the sectional width-height ratio and brace spacing. Under the same conditions, the bonding of the specimens with the inward-bent flange outperforms that of the specimens with the outward-bent flange. With different effects being considered, the formula of characteristic bond strength is calculated by statistical regression and the average bond strengthloaded end-slip constitutive model is presented. Based on two introduced position functions, the local bond strength-relative slip constitutive model (tau-S) of different longitudinal positions are established. In general, the calculation results of the statistical regression formula are in good agreement with the experimental result, the average bond strength-loaded end-slip constitutive model fits in well with the test curves, and the tau-S model of different embedded positions satisfies the accuracy of the finite element analysis.

为实现知识传授与价值引领相结合的课程思政,推进专业课程的课程思政建设,根据"工程结构抗震设计"课程的教学内容和专业素质要求,充分挖掘课程的思想政治内涵和德育元素,提出了本门课程的课程思政目标和实施思路.结合授课章节内容探索了课程思政目标的设计融入点,将专业知识教育和思想政治教育进行有机融合,提升了思想政治教育的亲和力和感染力,激发专业教师进行思想政治教育的积极性,提高学生学习的主动性和认同度.

An innovative double-skin composite wall (DSCW) with L-shaped connectors which can be quickly assembled and simply constructed was proposed. Taking the boundary column length and shear span ratio of the wall as parameters, the failure mode and seismic behavior of the composite shear wall were studied through quasi-static tests of four specimens. Based on the open-source software, OpenSees, the fiber model of the DSCW with Lshaped connectors was established, and the parametric study applied for the fiber model. The common failure phenomenon of each specimen lied in the steel plate tearing at the bottom of the end column, the concrete crushing at the tearing place, and local bulging at the bottom of the steel plate. Test results showed this type of composite shear wall had excellent bearing capacity and ductility, and the peak load range is 734.2 kN-991.3 kN, and the ductility coefficient is between 3.07 and 4.70. According to the analysis of the test results, the deformation performance and bearing capacity of the specimen were affected by both the length and the length -thickness ratio of the boundary column; the change in the shear-span ratio significantly affected the stiffness of the specimen in the elastic stage. With the comparison of the simulation results and the test data, the difference between the peak loads is less than 6%, which verifies the correctness of the model. Thus, taking the specimen model as the benchmark model, the parameters of the model were analyzed, as the supplementary verification of test results.

对节点区附近的钢管柱壁进行加厚,设计了一种无横向加劲肋的节点域柱壁加强型方钢管柱-H型钢梁节点.通过5个节点试件的低周反复加载试验,研究了轴压比、节点区柱宽厚比和有无竖向加劲肋对节点试件抗震性能的影响.结果 表明:各试件的滞回曲线形状较为饱满,刚度退化较为平缓,位移延性系数在3.0～4.1之间,等效黏滞阻尼系数在0.27～0.31之间,节点具有较好的塑性变形能力和抗震性能.随着轴压比的增大,节点的承载能力、延性和耗能能力均有所减小;随着节点区柱宽厚比的减小,节点的承载能力、延性和耗能能力均有所提高;节点区柱内设置竖向加劲肋,节点的承载能力显著提高,但延性和耗能能力相对较低.

In this paper, the authors' research group propose a novel double-skin composite wall (DSCW), which is composed of boundary columns, steel faceplates, L-shaped connectors and infill concrete. To further study the seismic performance of DSCW specimens, six high shear-span ratio DSCWs were designed and manufactured for a quasi-static test. In the experiment, the welding spacing, welding forms, and the thickness of the steel faceplate are used to set forth parameters; moreover, the failure mode, deformation performance and energy dissipation capacity of the DSCWs are analyzed. Test results show that the failure mode of each specimen was flexural failure, as shown by the fractured steel plate at the bottom of the boundary columns, the crushed infill concrete at the tear, and the specimens' buckled steel faceplates in different degrees. The average value of the yield drift ratio was 1/177; the average value of ultimate drift ratio was 1/39, and the average value of displacement ductility coefficient was 4.46. A good energy dissipation capacity was shown by the specimens as it increased gradually during the testing process. The results show that the local buckling of the steel faceplate can be delayed by reducing the welding spacing and adopting the blossom-form or dense bottom welding arrangement; thus, improve the ductility and energy dissipation capacity of the specimens. When the thickness of the steel faceplate is increased, the local buckling of the steel faceplate is less likely to occur, and the bearing capacity is improved. Based on the theoretical analysis, a buckling stress calculation model is proposed to calculate the buckling stress of the steel faceplate at the bottom of the specimen.

为了满足装配式建筑发展的需要,本文提出一种设置L型拉结件的新型双钢板-混凝土组合剪力墙.设计并制作了6片L型拉结件双钢板-混凝土组合剪力墙试件,对其进行了低周往复荷载作用下的拟静力试验.对试件的破坏现象、滞回性能、承载能力和延性进行了分析.试验结果表明:L型拉结件既可以有效地抑制两侧钢面板的局部屈曲,也可以增强对内填混凝土的约束作用,该新型组合剪力墙具有较高的承载力和一定的延性.基于开源软件OpenSees,建立了L型拉结件双钢板-混凝土组合剪力墙的纤维-分层壳模型,通过将其与传统的纤维模型和试验结果进行对比,验证了该模型的正确性,可为多腔体组合结构的数值模拟提供参考.

运用建筑节能软件PKPM对理想化建筑模型的各类型外遮阳进行全年能耗值计算.对比无外遮阳的全年能耗值,发现不同材料外遮阳均有利于建筑的节能.对比不同材料外遮阳的节能量,发现不同材料外遮阳的节能效果不同,钢筋混凝土外遮阳节能效果最优,玻璃外遮阳节能效果最差.对比各遮阳形式间不同材料的节能量最大差值,发现不同形式外遮阳节能效果对材料的敏感性不同,挡板式外遮阳对材料最敏感,垂直式外遮阳对材料最不敏感.

To meet the requirements of good seismic behavior, rapid assembly, and economic feasibility for a high-rise steel residential apartment, the authors developed two innovative double-skin composite walls (DSCWs) with L-shaped and C-shaped connectors. DSCWs are composed of concrete-filled double steel faceplates, which are divided into several compartments by connectors and two boundary columns filled with concrete at the ends of the composite wall. In this paper, eight DSCWs were tested under cyclic loads to investigate the seismic behavior of these new composite walls considering the effect of low axial compression ratio and spacing-to-thickness ratio. Results show that no significant buckling of steel faceplates was observed before the peak load was reached. No obvious pinching effect was observed on the hysteresis curves for all specimens. Ultimate drift ratio ranged from 1/59 to 1/45, and the ductility coefficients varied from 2.45 to 3.80. The equivalent viscous damping coefficient versus drift ratio curves were close to an exponential distribution, and all specimens exhibited great energy dissipation capacity. The strain on connectors was below the yield strain throughout the experimental process, indicating the connectors have a good working performance. Finally, formulas were established for calculating the load-carrying capacity.