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.

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 inverted Fink truss bridge, a novel structural system first appearing in the United Kingdom, has seen a gradual increase in its application in urban landscape pedestrian bridge construction over the past decade. This system presents significant differences from typical cable-assisted beam systems such as cable-stayed and suspension bridges, with the main design parameters' influence on structural performance remaining unclear. This paper first introduces the development of the inverted Fink truss structure. Subsequently, it focuses on a newly constructed inverted Fink truss bridge with uneven tower heights, employing finite element numerical simulation to analyze critical structural parameters such as tower height and cable tension within the cable-assisted beam structure. It summarizes the influence patterns of these parameters on structural performance and proposes feasible directions for stiffness optimization of such structural systems. The findings of this study provide a basis for the structural design of inverted Fink truss bridges with uneven tower heights.

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.

Due to the non-sufficient introduction on the derivation process of mass matrix of Timoshenko beam element in existed studies, the present study was initiated for the derivation of consistent mass matrix of Timoshenko beam element. Based on the Lagrange shape function and the virtual work, the theorical expression of mass matrix for each single motion state was given for the 2-node and 3-node elements separately, including the tension, torsion, bending-deflection and bending-rotation motions, and then the complete mass matrix was got by aggregation. Moreover, the simplified procedure in practical finite element calculation was also proposed for the tapered-section element. Another, the difference of the shape functions between the Timoshenko and Euler beam elements was also elaborated, as well as the difference in the derivation of the mass and stiffness matrixes concerning the bending condition. The results show that the Lagrange shape function was employed for all the deform conditions and especially the uncoupling of the deflection and rotation in bending conditions make the mass matrix for each single motion state shares the same form： each one is expressed by the corresponding section parameter and the same shape function. Additionally, the complete mass matrix based on this foundation is featured by the high degree of decoupling. For the tapered-section element, when the theoretical whole integration is simplified to be independent integration calculated by Gauss integration method in practical application, the obtained mass matrix shares the same form with the constant-beam element, just replacing the constant section parameters by the equivalent section parameters.

T-head Square-neck One-side Bolt （TSOB） is a novel fastener, which can be used for the connection of Square Hollow Steel （SHS） members, with its simple construction, easy installation, no additional aids, can adapt to the rough installation manners in construction site, and has a large application potential. In this paper, the Finite Element （FE） analysis software ABAQUS was used to establish the numerical model of TSOBs bolted beam to SHS column joints, evaluating the structural performance, and revealing the bearing and failure mechanism of such joints. Furthermore, the parametric analysis of TSOBs bolted beam to SHS column joints was carried out. The results show that the T-head aspect ratio of TSOB has a greater influence on the joint failure modes and bearing capacity. A suitable and optimal T-head aspect ratio can not only improve the punching bearing capacity of the bolt hole but also ensure that the mechanical properties of the joints are not affected by the slotted bolt holes. The influence of the rotation deviation and shank offset for TSOBs on the joint mechanical properties is minimal and can be ignored in the design. The arrangement pattern HVH for the slotted bolt holes results in optimum structural response of the joints and should be recommended in preference. Furthermore, medium assembly accuracy is recommended for the slotted bolt holes.

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.

The detachment and failure of openable windows of curtain walls have become one of the important reasons for curtain wall damage, yet there is still a lack of analysis and research on openable windows of oversized curtain walls and their connectors.In order to optimize the design of openable windows of oversized curtain walls and enhance their reliability during service life, this paper establishes a finite element model of openable windows of oversized curtain walls.By taking the opening angle, wind direction angle, number of window openers, and positions of window openers as research parameters, the stress distribution of components under different working conditions is calculated.The influence of each parameter on the stress of the components is compared and analyzed, and design recommendations for openable windows of oversized curtain walls are provided.For safety and economic considerations, it is advisable to install two window openers for oversized curtain walls, and for openable windows arranged according to the predominant local wind direction, the opening angle should be appropriately reduced.

A simplified analysis method for upper cover frame-shear wall structures of urban rail transit was proposed based on the flexure-shear type MDOF model in Opensees.This method can consider various structural schemes of upper cover frame-shear wall structure, including seismic-resistant structure, 15-meter-story individual isolation structure, 9-meter-story individual isolation structure and 9-meter-story monolithic isolation structure.The corresponding parameter calibration method was also presented.The accuracy of the proposed method was verified by comparing analysis with the finite element analysis results of an upper cover shear wall structure.Comparing the analysis results of the 15-meter-story individual isolation structure and the 9-meter-story individual isolation structure, it was found that the dominant vibration mode with the highest participation coefficient of the former is the third mode, mainly characterized by the vibration of the upper structure.On the other hand, that of the latter is the first mode, which has the longest period and mainly characterized by the vibration of the structure above isolation layer.The results of the elastoplastic seismic time history analysis show that the 9-meter-story individual isolation structure can reduce the inter-story shear force of the upper structure by 38.4% and that of the substructure by 71.4% compared to the 15-meter-story individual isolation structure, with 50% reduction of the inter-story drift.

The steel tower crown and the lower main concrete structure form the steel-concrete vertical hybrid structure. Due to the sudden change of mass, stiffness and damping ratio of the joint, the seismic whiplash effect is obvious, its overall dynamic characteristics under earthquake and the failure mechanism of components are still lack of in-depth research. In this paper, the seismic response of steel tower crown under frequent earthquakes is studied by numerical simulation method. The influence of structural damping ratio, equivalent mass ratio of tower crown and connection form between tower crown and substructure on its seismic performance is analyzed. The research shows that Rayleigh proportional damping can be used to simulate the damping ratio of the whole structure in the seismic analysis of the whole structure; for seismic analysis of the steel tower crown, the overall model can use the damping ratio of steel structure; for seismic analysis of the concrete structure, the overall model can use the average damping ratio of steel structure and concrete structure. With the equivalent mass ratio decreases of the steel tower crown, the influence of the tower crown steel structure on the seismic action of the whole structure is reduced. The steel tower crown and the lower concrete structure shall adopt the form of rigid connection as far as possible in the design, so as to control the deformation of the tower crown and the seismic shear force at the connecting part in the greatest extent.

The quality assessment of cement mixing piles has always been a controversial topic in the engineering field.To establish a more reasonable quality evaluation system for cemented soils, a rapid quality assessment method is proposed based on a comparison of existing research results and commonly used quality assessment methods.This method primarily utilizes cone penetration test （CPT） supplemented by core sampling strength test.Based on soil reinforcement projects in Shanghai, an experimental study was conducted on the relationship between the specific penetration resistance of cemented soil and the unconfined compressive strength （UCS） of the cores.The results indicate over 90% of the coefficients of variation of specific penetration resistance of cement mixing piles were found to be below 40%, which can serve as a quantitative evaluation index for the uniformity of piles.A clear segmented linear conversion relationship between the two parameters in the Shanghai area.This relationship was validated through indoor chamber tests, with a calculation error of about 13% A rapid quality assessment method for cemented soils in the Shanghai area is proposed.

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 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.

The externally inverted U-shaped steel-concrete composite beam （referred to as the USCC beam） has high bearing capacity, good ductility, steel saving, fire resistance and good corrosion resistance compared with the ordinary H-shaped steel composite beam （HSCC beam）. However, few study was conducted on the flexural performance of the negative moment zone of the USCC beam. In order to study the flexural performance of the negative moment zone of the USCC beam, the flexural test of 4 simply supported composite beams was carried out. The parameters studies included the type of steel beam forms, shear connectors and the arrangement of longitudinal reinforcement. Based on the test phenomena, load and deflection curves, load and slip curves were used to evaluate the mechanical performance of the beam. The analysis shows that the composite beam has complete shear connection performance, and the concrete slab and web are in good overall mechanical performance. Compared with HSCC beams, the USCC beam shows better ductility. In addition, the effect of channel steel connectors in resisting slip and controlling the development of section cracks is better than that of stud connectors. For the arrangement of longitudinal reinforcement, the shear-lag effect of the centralized arranged specimen is more obvious than that of the uniformly arranged specimen. To further study the performance of USCC beam, a finite element analysis （FEA） model was established based on the test results, whose effectiveness was verified. Based on the FEA model, parameters such as the thickness of U-shaped steel, the aspect ratio of concrete slab width to thickness and the aspect ratio of web height to width were analyzed. The results show that with the increase of U-shaped steel thickness, the yield height of the pure bending section decreases gradually, and the utilization rate of steel also decreases. The thickness of concrete slab has less impact on the bending performance. With the increase of web aspect ratio, the height of compression zone of web increases, and concrete utilization rate increases. When the width of concrete slab increases, stiffness and load-bearing capacity increase accordingly but shear-lag effect is obvious. Based on the plane section assumption and complete shear connection, a calculation formula for flexural capacity in negative moment zone was proposed. The calculated results are in good agreement with experimental and FEA results with a certain safety margin, which can be used for engineering design.

Four reinforced concrete （RC） I-girder specimens and three prestressed concrete （PC） I-girder specimens were designed with a shear span-to-depth ratio of 1.16 to investigate the effects of web reinforcement ratio, harped rebars, straight prestressing tendons, and harped prestressing tendons on the shear performance of prestressed concrete I-girders. The shear performance tests were conducted using a four-point loading method, and the failure modes, shear capacity, and load-deflection curves of each specimen were obtained. The results indicate that decreasing the web reinforcement ratio of stirrups can change the shear failure mode of RC I-girders from diagonal compression failure to diagonal tension failure. Harped rebars can enhance the shear stiffness and shear capacity of RC I-girders with minimal impact on the failure mode. Prestressing tendons do not significantly improve the shear stiffness of PC I-girders. Straight and harped prestressing tendons exhibit different mechanisms in enhancing the shear capacity of PC I-girders. Compared to RC I-girders of the same size and ordinary reinforcement, PC I-girders can achieve approximately 40% higher shear bearing capacity.

Aiming at the situation that the number of tension equipment and the maximum allowable tension force of equipment are limited during the construction of cable net curtain wall, and considering the influence of flexible boundary deformation on the tension forces, an automatic determination method of tension sequences and tension forces for cable net structures is proposed. This method changes the length of cable elements by adjusting the cable temperature to simulate the tension process of cables. Under the specified condition of limited number of equipment and maximum tension force, the tension sequences and tension forces were determined automatically through optimization iterations. Taking the cable net curtain wall of the Shanghai headquarters building of CCCC Group as an engineering case, the method was employed to carry out force-finding analysis of cable net structure. The tension sequences and tension forces of the cable net were determined, and the calculation results were compared with the conventional tension scheme. The analytical results show that the deformation of the main structure significantly reduces the value of cable forces, and the analysis of the shape-finding and tensioning process must consider the synergistic deformation of the main structure and the cable net. Compared with the conventional tensioning scheme, the proposed method can fully utilize the existing equipment, and effectively reduce the tension groups, ensuring that the cable forces do not exceed the maximum allowable tension force during the tensioning process.

The total amount of concrete pouring of Baojialin Yangtze River Spaning Crossing Tower completed is 2 304.8 m³, and the plane size of the pile cap is 14 m×12.8 m×2.5 m （thickness）, which is mass concrete. As the concrete is poured in one time, the temperature changes rapidly and the peak temperature is high. In order to avoid temperature cracks caused by the large temperature difference between the inside and outside of the concrete, this paper inverts the thermal parameters of the concrete for spanning tower in combination with the on-site measured data. In order to improve the efficiency and accuracy of the inversion, a new meta-heuristic algorithm, the crayfish optimization algorithm, is introduced. The performance of the new algorithm is validated by benchmarking functions and non-parametric tests. The inversion results are brought into numerical simulation, and it is found that the measured temperature of concrete matches well with the calculated temperature. Further verification was conducted using different temperature measurement points, which validated the performance of the new algorithm in practical engineering and the feasibility of parameter inversion. The inverse results can also be applied to the construction of large-volume concrete in future span tower projects.

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.

Based on project example, the stress state of curved box girder bridge with single-column pier was analyzed with different lateral offset values. A preliminary discriminating method for the degree of bridge disease was proposed, the disease situation can be acquired quickly and measures can be taken. The whole bridge jack-up scheme was put forward by analyzing the feasibility of jacking to correct the deviation, reconstruction scheme was proposed to improve the anti-overturning ability, effective solution for the anti-overturning strengthening of single-column pier beam bridges was provided. Site monitoring data shows the defect of torsion and bearing separation of the girder was improved after reconstruction, which can be referenced for other similar engineering.

The unbalanced force in a bended pressure pipeline results from the internal pressure acting at the bend location. The distribution of soil resistance to this thrust varies between sliding stability models in domestic and international practices, and there is no consensus formed in application. Combined with relevant engineering cases, the calculation principles of each algorithm are described, and the advantages, disadvantages and applicable premises of each model are analyzed. The fundamental principle of subsurface pressure pipeline anti-slip stability is proposed to be the interaction between the pipe and soil, based on a discussion and summary of recent experimental methods and theories by foreign scholars. It is recommended to use simplified formulas to fit the experimental data of pipe-soil interaction, with actual monitoring results used for verification, as a direction for further research on anti-slip calculation.

The total length of the Changchun indoor ski resort is about 443.4 m, which is divided into two structural units through the seismic joint.The length of the high-zone unit is 231 m, and the low-zone unit is 211 m.The width gradually changes from the straight section of 64.8 m to the widest section of 131 m and then decreases.The building adopts frame-shear wall system, and the roof of long-span pipe truss is supported by tall frame column above the ski run.The two independent structural units of the project are both out-of-code high-rise buildings, which have irregular torsion, low inter-story stiffness ratio, tower offset, inclined column, staggered floors, vertical dimension sudden change and so on.This paper introduces the macroscopic system optimization method of this kind of structure, as well as the analysis of the important and difficult points in the design of superstructure, such as the specific and reasonable arrangement of the lateral force resistance system of the structure, the type selection of special components such as large side columns, straddle columns, inclined columns, roof system, etc., and the key points of the analysis of temperature stress of ultra-long structures.The determination and analysis methods of seismic performance targets ensure the rationality and reliability of the superstructure system, components and joint forms.

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.

Connected structure is a common form of expression in modern architectural design. In this paper, the dynamic characteristics of towers on both sides of the connected structure are analyzed by taking a high-rise asymmetric twin tower as an example, which indicates the necessity of adopting the sliding connection in this project.At the same time, elastic analysis under minor earthquake, performance-based design, and elastic-plastic analysis under major earthquake are carried out for this project, with a focus on analysis of the connected structure, including force analysis, deflection analysis, finite element analysis of key points, and calculation of sliding support reaction and displacement. The results show that the structural design of this project is reasonable, the strengthening measures are effective, and the seismic performance can achieve the expected target. The connected structure has good mechanical properties, the structure is safe and reliable, and the design requirements for anti-collision and anti-falling are satisfied.

Isolated structures with rubber bearings have good seismic performance, and have been widely developed and applied at home and abroad in recent years. Scale model test method, as one of the important means to study and verify the performance of new structures or complex structures, plays an increasingly important role in the research and design of structural engineering and disaster prevention and reduction engineering. For model testing, using reasonable similitude method to carry out reasonable similitude design is the key to ensure the accuracy of the model test results. From three aspects of isolated superstructures, isolation layer and transfer layer, this paper focuses on the advances in the similitude design method for shaking table test of isolated structures with rubber bearings. At present, the dynamic similarity design of the superstructure model of the isolated structure generally refers to the traditional practical similarity design method. For the design of the isolation layer, it is necessary to revise the existing mechanical properties calculation formula of the isolation layer, and to select and arrange the number of supports according to the principle that the overturning stiffness of the isolation layer is similar. The reinforced transfer layer in the scale model can make the load area pressure of the support tend to be uniform and reduce the tensile probability of the support in rare earthquakes, and the effect should be considered in the seismic response analysis of isolated structures.