Chinese construction industry has made remarkable achievements in technological progress and engineering practice. The comprehensive strength of construction enterprises has been continuously enhanced, with leading technological advantages and engineering practice in many aspects. A relatively perfect national engineering construction standard system has also been established in China. This paper studies the current engineering construction standards in the field of high-rise buildings in China, and establishes the Hall three-dimensional model of the design and construction technical standards. Through typical case studies of structural seismic design in high-intensity areas and super-thick raft foundation construction in desert areas, the highlights and experience have been analyzed for the application of Chinese high-rise building design and construction standards in international contract projects, and the significant impact of the selection of the standard system has been explored on project quality, construction organization, project progress and cost. It is indicated that China has accumulated rich experience in high-rise building design and construction in project planning and management, design optimization, building material development, construction technology improvement and innovation. The adoption of China's engineering construction standards is beneficial to improving the performance of Chinese enterprises in overseas projects and promoting the high-quality development of Chinese foreign contracting business.

The assessment of post-earthquake damage and seismic performance level of buildings is key process of performance-based seismic design. To solve the problem of the lack of an evaluation indicator for the earthquake-induced damage of double skin composite shear walls （DSCWs）, an experimental database including 37 flexural composite wall specimens under hysteretic loading tests is made in this paper. Based on the existing modified two-parameter Park-Ang damage assessment model, the empirical expression of the combination coefficient β about the design parameters （axial compression ratio, shear span ratio, section length-width ratio, steel content ratio, etc.） of the DSCW is established. Based on the seismic design concept in Chinese code that three-level performance target and two-stage seismic design, the damage states of the DSCWs can be divided into four levels： basically intact, slightly or moderately damaged, severely damaged, and failure, according to the feature points of the skeleton curves. The critical values of the corresponding damage indices are 0.086, 0.517, and 1.020, respectively. The research results of this paper can provide a necessary basis for the earthquake-induced damage evaluation, performance-based seismic design, and post-earthquake reinforcement of the DSCW structures.

Concerning the orthotropic steel bridge decks under above-deck explosions, a numerical simulation study based on steel plate explosion tests was conducted. The damage mechanism of the steel bridge deck of Taizhou Yangtze River Bridge was analyzed under explosions of five threat types specified by the Federal Emergency Management Agency （FEMA）, and the damage modes of different components of the bridge deck were revealed. The main conclusions are as follows. In all explosion scenarios, petal-shaped openings on the top plate, fracture and tearing of U-ribs, and plastic deformation of cross beams were observed. For scenarios with larger explosive charge （1 814 kg TNT, 4 536 kg TNT, and 13 608 kg TNT）, the failure modes of the bridge deck also include outward bending, local buckling, and fracture of cross beams, fracture of the U-ribs, and openings on the bottom plate. In scenarios with smaller explosive charge （227 kg TNT and 454 kg TNT）, the main energy consumption mechanism of the bridge deck was the top plate and top plate U-ribs, accounting for over 70% of the total energy consumption. In scenarios with larger explosive charge, the main energy consumption mechanism of the bridge deck involved the top plate, top plate U-ribs, cross beams, bottom plate, and bottom plate U-ribs, accounting for over 90% of the total energy consumption.

Prefabricated concrete building is a kind of green environmental protection building which can improve production efficiency and save energy. In order to study the seismic performance of prefabricated concrete bolt welding and Z-shaped joints, this paper carries out low-cycle reciprocating load tests on middle joints, observe the failure of specimens, and analyze the load-displacement hysteretic characteristics, ductility, stiffness and energy dissipation capacity of middle joints. The test results show that the hysteretic curve of the specimen is full in shape and has significant slip and pinch phenomena, and the ductility coefficient of each joint meets the requirements of the code for displacement ductility and has good seismic performance. The connection mode of joints has a great influence on the stiffness degradation of joints, and the joints of fully fabricated concrete frames have good deformation performance and anti-collapse ability under seismic load.

With the development of high-rise building related technology and the improvement of living standard, while the seismic safety of high-rise buildings being focused on, greater demands are put forward for their comfort under wind loads. Evaluation of building comfort is subjective and uncertain, which needs a huge amount of literature review and analysis to develop more appropriate comfort evaluation standards. In this paper, based on the existing codes and engineering cases of high-rise buildings, the comfort standards and evaluation methods worldwide were systematically sorted out and their applications were summarized. With the analysis of the standards and cases, the problems and deficiencies in the existing comfort evaluation standards in China are proposed. Then the solution and future research directions are put forward. It is expected to provide the reference for the development of building wind-induced vibration comfort standards for high-rise buildings in China.

In this work the temperature of two side walls of a subway station under construction in Shenzhen was monitored, and then the temperature fluctuation characteristics caused by the heat of hydration in the large-volume concrete structure of the side wall of the subway station were analyzed. Then the phenomenon of concrete interior and surface, surface and environment, cooling rate and other phenomena was further analyzed, and the temperature change law of concrete was obtained. ABAQUS finite element software is used to simulate the whole temperature change process. A three-dimensional stress field-temperature field coupling model of the side wall was established, and the result was compared with the experiment data to verify its reliability. The stress state of concrete was analyzed, the principle of temperature stress was verified, the stress concentration of the subway side wall was predicted, and relevant measures to prevent cracks was proposed.

Based on the theory of one-time sampling inspection, balancing the risks of the manufacturer and the user, and considering the protection of the interests of the manufacturer, it is proposed that the evaluation coefficient k for strength average value should be corresponded to 90% the equivalent assurance rate （0.9 Quantile value） for both the known standard deviation method and the unknown standard deviation method, and the sampling scheme when the standard deviation is unknown is determined based on Bayesian theory. When the sampling size is very small, the acceptance criteria of non-statistical method is established based on the average quality standard deviation, and the minimum value acceptance criterion is proposed according to the theory of one-time sampling inspection. Using the concept of Bayesian method, the samples in the previous inspection cycle and the current inspection cycle are combined to expand the sample size and improve the test efficacy of the acceptance criteria with known standard deviation. Bayesian method is adopted to comprehensively consider the average quality standard deviation and the standard deviation of measured samples to improve the test efficacy of acceptance criteria of non-statistical method. The acceptance criteria proposed in this paper have a more clearly statistical basis. The unified equivalent guarantee rate is used to keep the test efficacy close to each other, and the Bayesian theory is used to unify the various methods into the statistical method with unknown standard deviation. The case analysis shows that the acceptance criteria proposed in this paper are slightly stricter than those in GB/T 50107—2010, but the variation range is within the acceptable range; after adopting reasonable prior standard deviation, the Bayesian improved method proposed in this paper can obtain scientific and reasonable evaluation results.

Tunnel engineering accounts for a large part of the road and railway projects in the dangerous mountains in southwest China. This area has large tunnel burial depth, complex geological conditions and frequent seismic activities. There are several engineering problems with small angle crossings between tunnel engineering and active faults. In addition, near-field earthquakes have different influences on surrounding rocks with different burial depths. Therefore, near-field earthquakes of active faults have significant adverse influences on the smooth construction and safe operation of tunnel engineering. Therefore, based on the impact of multiple disastrous earthquakes at home and abroad on tunnel engineering, the influence rules of historical earthquake magnitude on the damage of surrounding rock （surrounding rock burial depth, lithology and grade） of tunnels passing through the seismogenic fault are analyzed and summarized. Combined with the characteristics of active faults, the ground motion records that can reflect the regional fault characteristics and pulse characteristics are obtained. Finally, the finite difference software FLAC3D is used to study the influence of the active fault near-field earthquake on the surrounding rock of deep tunnel engineering. The results show that the tunnel surrounding rock is more stable with the increase of tunnel buried depth, which can restrain the plastic deformation of tunnel surrounding rock. The trend of maximum shear stress and maximum principal stress under different ground motions is basically the same, and the stress of tunnel surrounding rock in fault section is greater than that in ordinary section. The surrounding rock of Grade IV and below has a great displacement and stress response when the depth of tunnel is 200m and PGA is larger than 0.3g. The response level increases with the increase of PGA, and there is a large increase of nearly 50% in the process of PGA from 0.2g to 0.39g. This process is the main process of tunnel plastic deformation, and the area of plastic zone gradually increases with the increase of PGA. Therefore, the influence of near-field earthquakes should be carefully considered in deep-buried tunnels through active faults. The research results can provide technical support for seismic optimization design of tunnel.

This paper presents an experimental study on the self-healing effect of Engineered Cementitious Composites （ECC） under various conditions. First, specimens were fabricated using two different categories of fibers, and subjected to uni-axial tensile loading to reach different levels of pre-damages （non-linear strain）. Then the specimens were treated in different curing conditions for self-healing. Finally, a series of tensile tests were conducted on the self-healed specimens to evaluate changes in peak tensile strength, tensile strain capacity, tensile modulus and etc. The test results shows the damaged ECCs after healing treatment restored their tensile strength, tensile strain capacity to a certain degree and partial tensile modulus. The damage level, fiber category and curing condition have significant effects on the mechanical properties of ECC after healing.

As a novel structural system, the continuous rigid frame bridge without bearings has the advantages of good integrity and no requirement for replacement and maintenance of the bearings. However, the pier-beam connection joints of this type of bridges are complex and prone to damage and destruction under seismic excitation, while the cross-section of girders are substantially greater than the pier cap beam. To date, seismic performance of such joints is scarcely investigated around the world. Utilizing a 4×40m continuous rigid bridge without bearings in a standard section of an intercity railway as prototype, quasi-static tests were conducted on a 1/3-scaled connection joint model, to investigate the damage mode, hysteretic energy dissipation characteristics, and ductility capacity, as well as the failure mechanism under closing and opening bending moment. The observed results show that at the beginning of the test loading, horizontal cracks were mainly generated at the loading surface of the pier, and then gradually extended through, with fewer cracks developing at the diagonal edges of the joint and girder. As the loading displacement increases, cracks with small width gradually appeared at the diagonal side. Since the longitudinal reinforcement of the pier extended into the joint is only transversely designed with tie bars and no hoops, the significant arch damage was observed for the concrete at the top of the joint when subjected to closing moment. The force-displacement hysteresis curve was observed with small area with severe pinch effect. Although the longitudinal reinforcement at the top of the pier yielded when the joint was damaged, the ductility capacity was limited. Under the closing moment, the skeleton curve did not contain an obvious yielding plateau, and the lateral force experienced a sudden drop after reaching the peak, indicating the damage of the joint. Finally, based on the damage mode and damage mechanism, the reinforcement configuration of the side pier-main beam joint is suggested in conjunction with the AASHTO code.

The pushover analysis has the advantages of being easy to operate, having low computational costs, and being able to describe the overall nonlinear behavior of structures well. It is an engineering practical analytical method worth promoting and applicable for seismic performance-based design of general multi-story and high-rise building structures. However, this method has limitations such as difficulty in considering the influence of higher modes, significant differences in structural responses under different pushover force distribution patterns, and errors introduced by single-degree-of-freedom equivalence, which restrict its application in complex and irregular high-rise building structures.This paper considers the contribution of both fundamental and higher modes to the seismic response and combines the modes corresponding to sensitive modes into a final pushover force distribution pattern. This method is used to analyze the nonlinear seismic response of an oversized podium offset single-tower super-high building structure and is compared with the results of dynamic nonlinear analysis. The results show that the proposed method has good accuracy in predicting both the overall response of the structure and the yielding damage patterns of local components, with the additional benefits of high computational efficiency and strong applicability.

In order to investigate the dynamic response of the airport taxiway base under the combined excitiation of aircraft taxiing load and underpass subway running load. Based on the real-time monitoring of a taxiway in a coastal soft soil airport, acceleration sensors were placed near the subway line crossing the taxiway to obtain the dynamic response of the taxiway. The response signals of long and short period frequencies corresponding to subway loads are obtained by separating the response signals, and the main frequencies of the dynamic response of subway and aircraft are separated by comparing the amplitude of the long and short frequency signals in the frequency domain. The results show that the main frequency of dynamic response of aircraft is 5‒30 Hz, and that of subway is 30‒60 Hz. The dynamic response produced by the aircraft taxiing load to airport runway is more than 6 times that produced by subway crossing.

The rebound method has the advantages of no damage to the structural components, a large number of samples and flexible layout of the test area. However, the mean value and variance of the inspected strength may have a large deviation, so the accuracy of the strength characteristic value of the inspection batch estimated by the sampling inspection by variables is poor. According to the principle of single sampling inspection by attributes, based on the analysis and comparison of sampling characteristic curves, the estimation method of characteristic value of concrete strength of inspection batch is established considering that the acceptance probability of 0.1 unqualified product rate is 50% （the confidence level is 0.5）. The comparison of sampling characteristic curves and case analysis show that the estimation results of the proposed method is basically equivalent to that of sampling inspection by variables based on Bayesian method. Suggestions are put forward for optimizing the layout of rebound test area when evaluating the strength of test batch concrete, as well as the core drilling correction method for inspection results of rebound method by sampling inspection by attributes. The proposed method has the characteristics of accurate probability definition, avoiding the assumption of strength distribution type and variance calculation, and reducing the number of core drilling checks. It can be used in engineering quality compliance assessment and existing structure safety assessment.

A method for calculating the reliability index of structural components, which is convenient for use in commercial structural design software, is proposed in this paper. The finite difference method is used to calculate the partial derivatives of load effects on basic random variables. The moment propagation method is used to calculate the first and second moments of components' load effects. The first order second moment method is used to calculate the reliability index β of structural components. A secondary development procedure based on PKPM is written according to this method, which can calculate K and β of beams considering ultimate bending and shearing capacity in RC frame structures. The reliability index of an RC frame structure with a seismic fortification intensity of 6 is calculated using this procedure. The result shows that a few beams' reliability indices do not meet the code requirement under an earthquake with an intensity of 6, and under an earthquake with an intensity of 7,the reliability indices of most of the beams are lower than the code limit.

Spatial-cable suspension bridges consist of main cables and hangers inclined either to the inner or outer side in the transverse direction of the bridge. The hangers play a vital role in load transmission; however, their resistance decreases with the bridge's service life, leading to an increase in component failure probability and structural safety concerns. In this study, a steel box girder suspension bridge with a main span of 1666m serves as the engineering background, and seven designs of the suspension bridge with different inclination angles of main cables are proposed. By establishing the time-varying probability models of the resistance, internal forces under dead load and internal force under wind load only, the variation of the reliability index of hangers with the service period under the condition of the dead load and the extreme static wind load is analyzed and compared. The study shows that within ten years of the steel wire starting to corrode, the distribution of resistance of hangers affected by uniform and pitting corrosion does not reject the gamma distribution. From the 10th to 30th year, the distribution of resistance of hangers does not reject the Weibull distribution. The distribution of internal force of hangers under wind load only does not reject the logarithmic normal distribution within 40 years of service. The time-varying reliability index of all the hangers of the suspension bridge is uncorrelated with the inclination angle of the cables, and the variation of the time-varying reliability index of the hangers at different positions of the same suspension bridge is consistent.

Rebound method, core drilling method and rebound-core drilling correction method are commonly used in-situ concrete strength non-destructive detection methods, but the variance of concrete strength detected by rebound method is smaller than that by core drilling method, which is a common phenomenon in engineering practice. How to use the reasonable variance in the estimation of the strength characteristic value of the measured concrete directly affects the accuracy and rationality of the estimation result. Based on the statistical analysis of 120 existing structural concrete strength rebound core drilling correction method, the statistical parameters and their distribution rules of core drilling method and rebound method are obtained. It is suggested that 90% equivalent assurance rate should be adopted for the characteristic value of concrete strength in situ, and the evaluation coefficient corresponding to 0.1 quantile value is obtained by using Bayesian total probability formula. According to the mixed variance of rebound and core drilling method in the check area, and the calculated posterior variance by combining with the prior variance, the Bayesian estimation method of strength characteristic value of rebound-core drilling correction method is established, and the Bayesian estimation method of strength characteristic value of rebound method and core drilling method is obtained after simplification. Through the verification and analysis of the measured data of new projects and existing structures, it is shown that the Bayesian estimation method of strength characteristic values proposed in this paper is reasonable and accurate, which overcomes the defects of large error in variance value and insufficient sampling quantity in the current standard, and can be used in engineering quality compliance assessment and safety assessment of existing structures.

As the civil engineering industry undergoes a significant transformation, intelligent technologies have introduced novel technical means and tools for the innovation and advancement of structural health Monitoring （SHM） in civil engineering, thereby broadening the research scope in various aspects of SHM systems. This paper systematically sorts out and comprehensively reviews the current status of research on intelligent technologies applied in the field of SHM, covering areas such as computer vision, machine Learning, intelligent robots, and drones. Based on the review of existing research results, this paper looks forward to the development trends and prospects of intelligent technologies in the field of SHM, and deeply explores the innovations and challenges brought about by the integration of SHM and intelligent disciplines.

The Wujiang Rolling Pedestrian Bridge project is located at the border of two provinces and one city in the eastern part of Wujiang District. It is the main exit for yachts entering and exiting Yuandang Lake at the planned water town market node. It has high landscape requirements and requires a landmark architectural landscape pedestrian bridge. The bridge also has requirements for opening, so the rolling pedestrian bridge scheme is finally adopted after considering various factors. This paper introduces the special geographical location, scheme conception, navigation conditions, overall design, structural design, hydraulic design, opening sequence, etc. Through research, the project has achieved the expected landscape and opening performance goals, and the specific analysis methods and conclusions can be used as a reference for similar projects.

To study the influence of pile-soil interaction （PSI） on the near-field pulse seismic response of high-speed railway bridge-ballastless track system, the finite element model of the bridge-track system was established by ANSYS. The influence of PSI on the seismic response of the system was analyzed from three aspects： the natural vibration characteristics of the system, the post-earthquake residual displacement of each layer of the system and the key components between layers and the envelope displacement during the earthquake. The results showed： the natural vibration period of high-speed railway bridge-ballastless track system is extended considering PSI; the post-earthquake residual deformation and the seismic peak envelope deformation of each layer of main beam, base slab, track slab and rail are different considering or not considering PSI, and the post-earthquake residual deformation and the seismic peak envelope deformation of each layer of the track structure on simply supported beam and continuous beam bridge change alternately along the mileage direction; the influence of PSI on the key components such as fasteners, mortar layer, sliding layer and lateral blocks is obvious, especially for the key components with small stiffness. The influence of PSI on the key components between layers of the bridge-ballastless track system should be focused on in the anti-seismic checking calculation.

Earthquake monitoring networks has been established in Yibin area. A dense earthquake monitoring network for town and township is formed by eight monitoring stations in the rural region prone to seismic activity. Different from traditional strong-motion arrays, each station contains ground point and floor point of adjacent school buildings. A total of 2 000 records of ground and floor acceleration signals induced by 136 earthquakes were obtained, categorized into four types based on signal characteristics： epicenter zone, near zone, far zone, and very far zone signals. The data from the epicenter and near zone signals are valuable strong ground and floor acceleration signals and of large amount, with 56 records of ground and floor signals in region with epicenter distance less than 10 km. This paper selects representative data to analyze the characteristics of ground average response spectrum. The typical attenuation curve of peak ground acceleration with respect to epicenter distance is given. The very far zone and far zone signals with relatively lower peak values of ground and/or floor acceleration are also discussed.

In order to investigate the effects of different factors on the seismic response of steel plate silos when considering the storage-wall interaction, this study analyses the structural acceleration response, displacement response, the structural energy consumption and the structural strain response of the steel plate silos under the full-filled storage and the half-filled storage state, by establishing three steel plate silos with different height-to-diameter ratios. Moreover, steel plate silos and reinforced concrete silos with the identical dimensions are modeled and exited by the same seismic waves to compare the differences in structural acceleration response, displacement response and energy consumption of the two silos in the half-filled and full-filled conditions. The results indicate that the peak absolute acceleration and peak relative displacement of the silo wall increase with the increasing height to diameter ratio and reach a maximum at the top of the silo. While the cumulative hysteresis energy dissipation and stain of the silo decrease with the increasing height to diameter ratio. Moreover, for different silo types, the response of the reinforced concrete silo is smaller than that of the steel plate silo.

In order to improve the safety of component hoisting construction, this study explores a three-dimensional reconstruction method for prefabricated building component hoisting construction scene under multi-directional threshold. This method uses a 3D laser scanner to obtain scene point cloud data, uses the minimum curvature region growth method for scene segmentation, and uses a random sampling consistency algorithm for image fine segmentation to obtain a set of several disjoint planar point cloud regions. Using the moving least squares method for surface fitting, a three-dimensional parameter optimization model for construction scenes is established. By improving the sparrow search algorithm to solve the model, the optimization results of 3D model parameters are obtained, and the iterative reconstruction of the construction scene of prefabricated building component hoisting is realized. The experimental results show that this method can effectively collect point cloud data from component lifting construction scenes and achieve high-precision 3D reconstruction of construction scenes.

The amount of domestic construction spoil emission is significant, but the resource utilization rate is low. One feasible and high value-added way to utilize construction spoil is to produce nonsintered bricks. Firstly, the classification and main disposal methods of construction spoil are introduced, and the bottlenecks such as low-carbon dewatering of construction spoil raw materials and the difficulty of determining the process parameters are pointed out. Then, the common production process of nonsintered bricks along with the influence of molding, curing and other processes on the performance of nonsintered bricks are introduced. Next, the type of cementitious material and mixing, moisture content, admixtures and other factors on the mechanical performance of nonsintered bricks are further analyzed, and the resource reuse and low-carbon advantages of nonsintered bricks are summarized. The defects such as smooth surface not easy to combine with mortar, low shear strength, large dry shrinkage deformation, etc. are also reviewed. Finally, the future direction of research on nonsintered bricks from the perspective of green building is put forward.

The integrity analysis of the reactor plant under steam explosion was numerically studied for the potential safety problem of the cavity.Firstly, a refined reactor plant finite element model （FEM） was established, and verified comprehensively based on a slab explosion test.Secondly, the damage scope of the reactor plant under steam explosion was determined qualitatively based on the damage contours.Then, the damage mechanism of the reactor plant was revealed based on the displacement- and strain-time histories quantitatively.Next, the tightness performance of the nuclear containment was analyzed according to the tensile strain contours and the damage threshold.Finally, the influence of foundation strength on the blast resistance of the reactor plant was analyzed and recommendations for the design of the nuclear power plant （NPP） were proposed.It derives that： under steam explosion, the cavity wall endures complete damage and the main damage mode is tensile failure.Besides, concrete at the cavity bottom within the depth of 2 m enters plastic state with shear failure; under steam explosion, the NPP containment is safe and the tightness of the containment is good.

The special-shaped building located on the steep slope is difficult to be realized with the conventional structure supported by foundations with different elevations or stilted building structure. Aiming at the special-shaped building under this terrain, a arch with inclined column structure was proposed and designed, which can not only better adapt to the architectural shape, but also solve the problem of foundation setting. Aiming at this structure, the influence of key parameters such as arch axis shape, arch rise-span ratio, arch tilted angle and column tilted angle on the mechanical performance and arch warping effect were analyzed in detail by using parametric analysis method. The results show that rise-span ratio has little influence on the bending moment of the arch and great influence on the axial force of the arch. Meanwhile, rise-span ratio also has great influence on the stability of the structure. Considering the architectural effect, structural force and structural stability, the rise-span ratio of the arch should be controlled between 0.2 and 0.3. When the rise-span ratio of arch is between 0.2 and 0.3, the influence of arch axis shape on structural stress can be ignored. With the increase of arch tilted angle, the section torque of arch increases rapidly, and the warping effect of arch foot and vault is obvious. When checking the strength of steel box section, the warping effect should be considered. The increase of column tilted angle reduces the internal force of arch, which is conducive to the stress of arch, and the stress of the structure can be improved by adjusting the tilted angle of the column.

Precast concrete double skin shear wall （PCDSSW） is a new-type semi-prefabricated concrete structure element with sound structural integrity, high construction efficiency and low demand for formwork and labour. It consists of two precast concrete panels and one cast-in-place （CIP） layer between them. In order to investigate its mechanical behavior under lateral loads, finite element simulations were conducted using the software ABAQUS after the models had been proved reliable by comparison with the existing test data. The parameter analysis of vertical connections, design axial compression ratios and the concrete strength of CIP layers were carried out on 21 PCDSSW models. Analysis results indicated that the load-displacement curves of the walls with single-row dowel bar connection, double-row dowel bar connection and those without dowel bars in the middle walls were similar. The lateral load capacities of the walls with single-row dowel bar connections were 1.5%~7.5% higher than those with double-row dowel bar connections, and the capacities of the walls without dowel bars in middle walls were 5.7%~12.3% lower than those with double-row dowel bar connections. Secondly, the initial stiffness and load capacities of walls increased significantly with the axial ratios, while the load capacities and stiffness declined more rapidly under high axial ratio. In addition, low concrete strength of the CIP layers caused by insufficient vibration would lead to low load capacities, which should be avoided in construction.

The application of cold-formed steel in prefabricated structures has inherent advantages. In order to expand the range of use of cold-formed thick-walled steel structures and avoid its shortcomings, this paper designed six new layered assembled “cross-shaped” beam-column joints and conducted cyclic loading tests to investigate the failure mode, initial stiffness, skeleton curve, equivalent viscous damping coefficient, energy dissipation coefficient, secant stiffness, hysteresis curve and strain distribution in key parts of the beam-column joints. The main conclusions were drawn as follows： Through the sliding of bolts and node plates, semi-rigid nodes have a certain energy dissipation capacity. Adding high-strength bolts can improve the bearing capacity initial stiffness and energy dissipation capacity of beam column joints as well as avoid bearing pressure on the bolt hole between the beam end and the connecting plate. Adding replaceable node flange plates has no significant impact on the failure mode of beam column joints, but significantly improves their bearing capacity, energy dissipation capacity, and initial stiffness.

The flat grid structure is widely used in large-span spatial steel structure system because of its good integrity, large spatial stiffness and flexible layout. The research focuses on the evaluation and reinforcement of a flat grid structure's bearing capacity, which is critical in cases of member damage due to factors such as material aging or construction issues. In this paper, SAP2000 finite element software is used to analyze the stress of a typical orthogonal square pyramid grid structure. According to the change law of mechanical index of grid structure after damage of different positions and numbers of members, a new calculation method of damage factor of grid structure is proposed. The calculation method has fewer parameters, simple calculation and high accuracy. The method of evaluating the bearing capacity of the grid structure and determining the repair measures according to the structural damage factor is proposed. For the grid structure that needs to be reinforced, this paper proposes a reinforcement method based on the importance of members.

In order to determine the performance difference of the network tied-arch bridge with different deck structure, three types of bridge deck structure, namely concrete deck, orthotropic steel deck and steel-concrete composite deck, are used to design and study the 300 m span bridge. The finite element software ANSYS was used to establish three trial design scheme models, and compare their overall mechanical performance. At the same time, the amount of materials was counted, and the unit price of materials was introduced to compare their economic performance. The results show that the concrete deck has better economic performance for the 300 m network tied-arch bridge. Compared with orthotropic steel deck, concrete deck or steel-concrete composite deck can improve the structural stiffness to a certain extent. The distribution of internal force and stress along the longitudinal direction of the network tied-arch bridge is similar in different types of bridge deck, while the axial force of the structure and cable force at the bridge completion stage is significantly different.

The beam deflection control in current structural design standards is to ensure the serviceability function of the building, while the deflection limit value in the reliability assessment of existing structures and the deflection early warning value in structural health monitoring also have the purpose of controlling the safety of structural members. Aiming at the safety control of structural members, this paper established a theoretical relationship between the deflection to span ratio of beams and the maximum tensile strain of steel bars,and the calculation methods and recommended values of the mechanics characteristic coefficient, the section neutral axis height coefficient and the long-term deflection growth coefficient of the beams were studied. The relationship between beam deflection and maximum tensile strain of steel bars was verified by the experimental data, which showed that the accuracy of the comprehensive coefficient of the deflection to span ratio proposed in this paper meets the requirements of engineering calculation. The graded control method of maximum tensile strain of steel bars was established, and the graded limit of deflection to span ratio of beams was proposed accordingly. Compared with the deflection limits in current standards, the results showed that the deflection limits proposed in this paper are significantly different according to the specific characteristics of the beams. The range of the deflection limits is wider and more stringent than the current standards. The research findings in this paper can provide references for reliability assessment of existing structures and structural health monitoring.

The frame-shear wall structure system was used in Photoelectric Information Building in Huazhong University of Science and Technology. A long-span structure with a span of 40 m was accomplished by using a multilayer vierendeel truss crossing 4 floors. The structure involved with structural irregularity problems such as the torsion irregularity, eccentric arrangement, slab with large opening, mutation of the bearing capacity, discontinuous structural elements, and regional skip-floor columns. A comparative study on the braced truss and multilayer vierendeel truss was conducted in this paper. The mechanical mechanism, internal forces of elements under vertical load and vertical seismic action, comfortability of the slab, design of the complex joint, the construction technique requirements, and behavior under rare earthquakes were analyzed. The measures were developed to reinforce the seismic capacity of the structure. The structure scheme of the multilayer vierendeel truss not only can meet the requirements of relevant codes and achieve the expected objective of seismic performance but also can meet the requirements of architectural function.

To study the bearing capacity, deformation, and failure pattern of steel tube specimens filled with aluminium foam under quasi-static axial load, specimens with different lengths and thicknesses were tested, and the final failure pattern and axial force-displacement curve were obtained. On the premise of the reliability of the finite element numerical model, the influence of the section height of the steel tube filled with aluminium foam was analyzed. The research results show that the peak load and average load decrease with the increase of specimen length, whereas increase with the increasing thickness of the steel tube. Compared with the pure steel tube, the total energy growth rate of the steel tube specimen filled with aluminium foam with a cross-section height of 40 mm, 50 mm, 60 mm and 70 mm fluctuates within a certain range, and the steel tube specimen filled with aluminium foam with larger height-to-width ratio of section can resist deformation more effectively. The mechanical properties of the aluminium foam-filled steel tube specimen with a length of 150~250 mm and a rectangular section aspect ratio of 1.5 are best after buckling.

GFRP bar-UHPC members have excellent mechanical property and durability, and have wide application prospects. The bond performance between GFRP bars and UHPC is a key issue for the two materials to work together. Pull-out tests were carried out on 12 and 4 GFRP-bar-UHPC specimens under monotonic and low-cyclic loading respectively to study the effects of GFRP bars' surface treatment, bond length and cyclic loading on mechanical properties such as failure mode and bond strength. The results showed that all specimens exhibited pulling-out failure. The bond stress-slip curves of wire wrapping GFRP bars specimens exhibited more significant fluctuations up and down after the peak load. The bond strength between GFRP bars and UHPC decreases slightly with the increase of bond length. The bond strengths of wire wrapping GFRP bars specimens were higher than these of sand coated specimens. Meanwhile, the effect of low-cycle loading on the bonding properties of GFRP bars in UHPC was mild. Finally, based on a model proposed by Yoo, a bond strength prediction model considering surface features of the bar has been proposed.

Based on the nacre toughing mechanisms, Engineered Cementitious Composites （ECC） were used as constructing mortar to improve the ductility and toughness of masonry structure. Five groups of masonry prisms with four types of bricks were carried out. The failure mode, stress-stain curve, ductility and toughness were comparably analyzed. The results demonstrated that the nacre-inspired masonry prisms had interface-slip and crack-deflection failure mode, which increased the ductility by a maximum of 10 times and the energy consumption capacity by a maximum of 77 times compared with conventional masonry. However, the brittle splitting failure occurred when ECC layer couldn’t provide sufficient confinement with the strength increease of brick layer. Based on the Digital Image Correlation （DIC） method,the collaborative work characteristics between brick and ECC lager was studied and the toughing mechanism was also discussed.

Based on scaled physical model tests and three-dimensional finite element numerical simulation, the lateral bearing capacity and failure characteristics of grouted sleeve connected bridge piers for overpasses were studied, and their energy dissipation characteristics were explored. The cyclic loading test results of the grouting sleeve connected pier column indicate that there was no node failure before the pier column failure, and its mode was column bending failure. A refined finite element analysis model for grouted sleeve connected bridge piers was established, and an elastoplastic damage constitutive model for concrete was introduced to simulate the mechanical response and damage process of the bridge piers under reciprocating cyclic loads. Further analysis was conducted on the influence of axial compression ratio and prestressing level on the bearing capacity of bridge piers. The results showed that a high axial compression ratio is beneficial for improving the lateral bearing capacity of grouted sleeve connected bridge piers, but it will reduce their energy consumption and ductile deformation performance. Pre stressing can increase the lateral bearing capacity of bridge piers, slightly increasing their energy dissipation capacity, but reducing their ductile deformation capacity.

On the basis of the parallel four-cable suspension bridge, four-cable suspension bridge with different sag solves the construction problem of limited height of the bridge tower, and lowers the main cable under the deck to maximize the sag of the main cable. As the critical load-bearing member of the suspension bridge, the axial force effect of the main cable under vehicle load deserves attention. Taking a four-cable super-span suspension bridge with different sag under construction in China as the research object, a structural finite element model is constructed by ANSYS, and the mechanical performance of four cables under vehicle load is analyzed. The results show that the distribution of dead load in cables with different sag is uniform. Under the action of symmetrical vehicle load, the lower cable will bear more vehicle load, with a distribution ratio of about 26.2% and the upper cable about 23.8%. Under the action of asymmetric load, the axial force of the lower cable on the action side can reach 34.6% of the total axial force, which is about 32% higher than that under the symmetrical load. The load distribution ratio of vehicles is independent of the change of traffic volume and the weight distribution.

Offshore wind turbines （OWTs） are subjected to random wind and wave loads for a long time during use and are in a state of continuous vibration. The design of their dynamic characteristics is very important. A three-dimensional finite element model for frequency analysis of an actual monopile support structure for the offshore wind turbine under actual seabed foundation condition was established by using ABAQUS. Compared to commonly used soil spring model,the model can consider the actual three-dimensional soil conditions directly and no need to simplify the soil artificially, avoiding errors caused by simplification.. The correctness of the method is verified by comparing the reference value. Unlike traditional optimization for the cross-section of support structures, the article considers changing the pile types. Four types of special-shaped piles, including an extended pile, a pile with a cover plate, and two types of piles with wings, were designed on the basis of the ordinary monopile. The influence of pile types on the natural frequency of monopile support structures for offshore wind turbines and the performance of support structures with different pile types under scour were studied. The results indicate that taking into account the effect of frequency increase and the difficulty of piling, the use of piles with a cover plate on any soil seabed is the optimal way to increase the frequency of support structures for offshore wind turbines. Scouring can reduce the frequency of the support structures, and the impact on the pile with a cover plate is the greatest, which requires special attention in design.

After long-term service on a long-span suspension bridge, the cable force of some hangers can easily deviate from that of the completed bridge. However, the effect of the change in local hanger cable force on the bending moment of the whole main girder is unknown. In this paper,the Wuhan Yangluo Bridge is taken as the research object, and numerical analyses of a long-span suspension bridge are carried out. The validity of the finite element model is verified by comparing it with actual bridge test data. Based on the verified numerical model,a parametric analysis was carried out to study the effect of 10%, 15%, and 20% negative deviations of local single and three suspender cable forces （less than the cable force of the bridge） on the maximum bending moment of each beam section of the steel box girder. The results show that the negative deviation of single or three suspender cable forces is linearly related to the bending moment variation of a steel box girder. When the single suspender cable force has a 20% negative deviation from the bridge state, the bending moment of the steel box girder increases by 40% to 97%. When the cable force of the three suspenders has a negative deviation of 20% compared with the bridge state, the bending moment of the steel box girder increases by 195% to 445%.

The construction details and working principle of viscous damper is introduced. Taking a kindergarten located in an 8-degree seismic fortification area as an example, five natural earthquake waves and two artificial earthquake waves are selected by using the Midas Gen finite element analysis software to analyze the dynamic response of the structure under frequent earthquake and rare earthquake, and the energy consumption of the viscous damper under the three-level earthquakes is given. The results indicate that with the addition of viscous damper, the main structure has good seismic performance and can achieve the "three-level" of seismic fortification goals. Under rare earthquakes, the overall plasticity of the structure is relatively low, and the damage yield mechanism is reasonable. Viscous damper exhibit good energy dissipation characteristics under earthquake action, providing a lower additional damping ratio under rare earthquakes than under frequent earthquakes,and the dispersion of additional damping ratios for multiple sets of seismic waves is also lower. This work can provide reference for similar projects.

Based on the OpenSees platform, a finite element model consisting of displacement-based beam-column elements and zero-length elements is developed for cyclic pushover analysis of columns, considering the plastic flexural deformation and bond-slip effect. The influence of the element length for the plastic region on the elastoplastic performance of columns is analyzed, and the reasonable element length is discussed. Finally, the numerical model is validated based on the quasi-static tests of three reinforced concrete cantilever columns with flexural failures in the PEER structural test database. The results show that the length of the displacement-based beam-column element in the plastic region has significant effects on the horizontal strength and displacement ductility of the column. The reasonable element length should be equal to the equivalent plastic hinge length, which can be calculated using the empirical formula proposed by Priestley et al.