In order to create a column-free open space for architectural performance of Beijing Daxing International Airport Terminal, a mega grid structural system that seamlessly integrated the supporting structure and roof structure was proposed based on several large-scaled substructure units which have independent load bearing capacity. The key issues, such as vertical and lateral bearing capacity, anti-progressive collapse capacity, seismic resistance capacity of this structural system were studied and the vertical seismic response was analyzed. The results indicate that the structural system created through integration of several large-scaled substructure units which have independent load bearing capacity has significantly improved load bearing and anti-progressive collapse capacity. The triangular supporting system, which is created through combination of the C-shaped columns and two supporting cores or braced supporting frames, has significantly improved the bearing capacity by more than 300%. The connecting elements between substructure units have critical effects on the loading mechanism of the mega structure, therefore both individual substructure unit model and global model should be designed simultaneously to provide enveloped design. The seismic shear force apportioned by the roof supporting elements should be adjusted if the proportion is smaller than the proportion of gravity loading they withstand, so as to improve their lateral resistance capacity. The anti-progressive collapse analysis conducted for both supporting structural system level and structural element level can provide an effective assessment for the importance level of different C-shaped columns and structural elements. The vertical seismic response calculated through static method is underestimated, mode-superposition response spectrum method or dynamic time history analysis method should be used for validation. The combination of base and interlayer seismic isolation technology can effectively improve the seismic resistance capacity of the mega grid structural system.

Domestic-produced Galfan fully locked coil cables are used for the National Speed Skating Oval(NSSO) due to their advantages in procurement duration and cost efficiency. In order to obtain the fatigue durability of the cable, an experimental study for this fully locked coil cable series was carried out under a simulated loading state equivalent to the cable service state in NSSO. The cable loading ranges and bending angles in experiment were finalized to be consistent with the structural response (loading and deformation) of the cable net structure of NSSO calculated under 100-year return period wind load. The deviation of elastic modulus of fully locked coil cable under different fatigue cycles were measured. The test results demonstrate that under normal service condition, the fatigue cycles of the cable of NSSO can reach 2 million times under bending status, which can satisfy the 100-year design life requirements of the project. When the bending angle exceeds its maximum angle under design service condition and reaches 4°, the fatigue cycle can still reach 2 million times as well, but wire fracture is observed on the cable body. When the cable is further loaded to its design strength, wire fractures at the outermost layer can also be observed, the fracture location is far away from the anchor point and the cable clamp, and the fatigue cycle under this condition can reach 0.4 million times. The SEM micrograph of the fractured wire shows that the fatigue crack initially appears at the inner corner of the outer layer wire, which matches the location of the maximum principal tensile stress obtained through finite element analysis.The initial elastic modulus of the tested fully locked coil cable is around 170-180 GPa. An increasing trend of elastic modulus is observed with the increasing fatigue cycles, regardless of small amount of wire fractures.

In order to verify the seismic performance of a 522 m high-rise structure in the 8-degree seismic intensity zone, a 1/40 scale structural model was design and fabricated. By means of shaking table tests, the dynamic characteristics of the structure were studied under the action of 8-degree frequent, fortified and rare earthquakes. And the deformation and damage of the structure under the actions of one-dimensional and three-dimensional earthquakes were investigated. In addition, ABAQUS software was used to carry out an elasto-plastic time history analysis of the structure under the action of 8-degree rare earthquake. The displacement response and dynamic characteristics of the structure simulated by the finite element method were compared with the shaking table test results, and the damage status and weak parts of the structure were analyzed. The results show that the structure has good stability and structural efficiency due to the double structural lateral force resisting system formed by the outer frame cylinder consisting of the mega-columns, the mega-diagonal braces and the ring belt trusses and the core of the combined steel-concrete structure. The structure does not collapse under the action of the 8-degree rare earthquake (0.3 times of the gravitational acceleration), which well meets the performance requirement of ‘no damage under frequent earthquakes and no collapse under rare earthquakes'.

High-rise building with large aspect ratio and length-width ratio has the typical characteristics of low efficiency of resisting lateral force, difficulty in controlling torsional vibration and difficulty in ensuring wind vibration comfort. The key issues to be considered in the design of this kind of building are the selection of efficient lateral force resistance system scheme and the reasonable yield mechanism of the lateral force resistance system under earthquake actions associated with different level of exceeding probabilities. For a super high-rise steel structure building in Nanjing, the combined lateral resistant system composed of steel frames, steel braces and steel shear walls was adopted after multiple schemes comparison. The analysis and performance study were conducted on the combined lateral resistant system. The experimental study was conducted on a sub-structure consisted of concrete-filled steel tube column and steel plate shear wall with large aspect ratio as well. The results show that the combined lateral resistant system can meet the stiffness and torsion control requirements of structures with large aspect ratio and length-width ratio, meet the predetermined seismic performance objectives of structures, and realize orderly and controllable degradation of seismic defenses by arranging the lateral force resistant members reasonably. The steel plate shear wall structure has high bearing capacity and sufficient ductility, and the design concept of ‘preferential yield' and ‘high energy consumption' is realized.

To investigate the wind-induced torsional effect and wind-induced vibration control measures of the super-tall building with a large side ratio, a pressure test on rigid model in the wind tunnel was conducted. Base-moment coefficients, wind-induced acceleration responses and equivalent static wind loads of the building under varying wind directions were studied, and effects of torsion on comfort index were analyzed. Aiming at the large wind vibration acceleration and the coupling of translational vibration and torsional vibration, the active/passive switchable hybrid tuned mass damper (ATMD) was used to control the wind-induced vibration of the structure. The parameters of ATMD and the mass strokel under extreme conditions such as earthquake excitation were studied as well. The results show that the building with a large side ratio has larger base-torque coefficients, the correlation of wind-induced effect between torsion and y-direction (paralleled to building short side) translation is significantly strong. The wind-induced torsional effects have a prominent contribution to acceleration responses. The calculation of lateral and torsional wind loads of the building with large side ratio exceeds the applicable scope in current code and cannot be ignored, thus they have to be determined by wind tunnel test and wind vibration response analysis. ATMD can simultaneously control the translational and torsional vibration responses of the structure induced by wind, and improve the wind vibration comfort of structure.

The steel canopy structure of Beijing Workers' Stadium is an open single-layer flat thin arch shell structure with friction pendulum isolation bearings around it. In order to improve the structural overall stability efficiently, finite element modelling was conducted considering overall initial imperfection of the structure and four segments subdivision of the components. Univariate sensitivity analysis was carried out including eleven parameters in three categories, e.g., the overall shape of the arch shell, the sectional size of the components and the support stiffness. The mechanical properties of the structure were evaluated through buckling analysis, elastic and elastoplastic whole process analysis. The results show that a strong linear correlation between the critical coefficient of elastic whole process analysis and buckling analysis is found. The average ratio of the former to the latter is 0.535. The average plastic reduction coefficient is 0.418. Parameters on overall shape of the arch shell are relatively sensitive, among which the height difference of the arch ends is the most sensitive one. The sensitivity of arch and outer ring beam is relatively high among the parameters of sectional size of components. The sensitivity of support stiffness is relatively low. The design process of structural overall stability was proposed. The overall stability design efficiency could be improved by synthetic analysis of sensitivity analysis result of eigenvalue buckling analysis, load bearing capacity redundancy of the component and the failure member type in elastoplastic whole process analysis.

To solve the problems of large connecting force and complexity of large-span structure connecting high-rise buildings in coastal areas under wind and earthquake loads, a hybrid isolation technology based on the friction pendulum bearing and switchable fluid damper was proposed. The damping force characteristic of switchable fluid damper, combining viscous damper and hydraulic valve, was experimentally studied. And a multi-performance objective design method for large-span structure connecting high-rise buildings was proposed in this paper. The results demonstrate that the isolation frequency of the large-span structure should be taken as the optimal frequency of the tuned vibration system to minimize the displacement of high-rise buildings. The switchable damper achieves velocity-dependent damping force and displacement-dependent damping force. Compared with the friction force of the friction pendulum bearing, the displacement-dependent damping force of switchable fluid damper is not affected by the wind load, and the control effect on sliding displacement is better. The velocity-dependent damping force is employed to achieve the seismic performance in cooperation with the friction force of the friction pendulum bearing.

In large cable structures, cables are the main load-bearing members. The analysis of the influence of cable break on the structure is the key to the design of large cable structures against progressive collapse. A number of large cable structure projects, such as Five-hundred-meter Aperture Spherical Telescope(FAST), National Speed Skating Oval, Qatar Lusail Stadium, Sanya International Sports Industry Park, Rizhao Kuishan Sports Center Stadium, Dalian Barracuda Bay Soccer Arena, were selected to study the dynamic response of structures after cable break using the dynamic analysis method according to the situation of typical cable breaking in these structures, and the characteristics of dynamic response and dynamic coefficients of cable structures, such as cable net(bidirectional orthogonal, triangular mesh) and spoke-type cable truss(single ring cable, double ring cable, inner ring with rigid canopy), after cable break were summarized. The analysis results show that, except for triangular mesh single-layer cable net, the dynamic coefficients of other types of cable net and spoke-type cable truss are greater than the recommended values in code after cable break, so dynamic analysis method is recommended for cable break analysis. Rigidity, stability and internal force redistribution ability of bidirectional orthogonal single-layer cable net are less than those of triangular mesh single-layer cable net, so the dynamic effect caused by cable break is larger. Compared with the double-looped spoke-type cable truss structure, the mutual dynamic effect after cable break between radial cables and looped cables of the single-looped spoke-type cable truss structure with staggered arrangement is smaller. For spoke-type cable truss structures, when the top chord of the cable truss is provided with membrane arches and cross secondary cables which are arranged in the same direction as the radial cable, or when there is a rigid canopy around the ring cable, the dynamic effect of cable break can be effectively reduced.

Beijing Workers' Stadium is a large-span lattice shell structure with steel roof isolated by three-dimensional friction pendulum bearings (3D-FPB) at high position. Compared with traditional FPB, 3D-FPB shows much lower stiffness in vertical direction, which can reduce vertical earthquake action and adjust uneven vertical uplift between bearings. A finite element model of isolated large-span lattice shell was established in ABAQUS, which contained 3D-FPB to simulate the uplift of slider on sphere surface. The results of elastoplastic time history analysis under rare earthquake action indicate that, compared with the same lattice shell model equipped with traditional FPB, the vertical earthquake reaction force of lattice shell equipped with 3D-FPB and vertical acceleration of overhang components are reduced. Meanwhile, the stress level of components sensitive to vertical earthquake is decreased, and the vertical force of adjacent bearings distributes more evenly. Considering the non-uniform uplift of bearings during sliding, the vertical earthquake reaction force of lattice shell and vertical acceleration of overhang components are increased. The lattice shell of this project keeps elastic during loading process, thus is associated with enough sufficient safety reserve.

To improve the applicability of large span spatial structures, a large span structure with tie-down vibration-reduction cable is proposed. By connecting the structure and the fixed body with tensioned cable, the vertical deformation and vibration of the structure under service load can be reduced. Through theoretical derivation, the dimensionless parameter R which represents the key characteristics of the large span structure with tie-down vibration-reduction cable is proposed, and the calculation methods of the minimum tension force of the cable, internal force, deformation, natural vibration frequency and amplitude shape curve of the structure with the cable placed in the middle or not in the middle are derived. It is suggested that the cable should be placed in the middle to improve the work efficiency. The case study shows that the vibration acceleration of structure can be reduced by more than 50% with the existing of tie-down cables, and the vertical deformation of the structure can be decreased by more than 90%. Through finite element analysis, it is found the dynamic effect caused by relaxed cable will significantly amplify the vertical displacement and the acceleration of the structure, so the cable needs to be properly tensioned. Finally, the design process of the structural system is proposed. According to the difference between the characteristics of the structure without cable and the performance objective, it will significantly improve the design efficiency to set a reasonable R value before the cable design.

The prestress plays a major role in stabilizing the cable structure as well as in forming its stiffness and load-bearing capacity. To obtain a feasible prestress for cable structure, it is a necessity to find the prestress modes considering multiple factors such as the geometric symmetry. The meaning of the equilibrium matrix is reinterpreted, after which the concept of the generalized equilibrium equation and the generalized equilibrium matrix are introduced. The expanded generalized equilibrium matrix is then derived by combining the equilibrium matrix with the generalized equilibrium matrix. The prestress modes, which conform to the predetermined prestress pattern, can be obtained by the singular value decomposition (SVD) of the expanded generalized equilibrium matrix. The feasible prestress modes for three examples are calculated using the proposed method. The results show that the method, provided with a proper prestress pattern, offers a simple and direct force-finding process in which the SVD is performed only once to calculate the feasible prestress mode. The prestress pattern can be determined flexibly as required, thus making it easier to find the feasible prestress mode that meets the design idea.

The perimeter of the outdoor grandstand and the cornice ring beam of Beijing Workers' Stadium is about 800 meters, which is a super-long concrete structure, and the temperature expansion joint was cancelled during the reconstruction. In this paper, the temperature effect of the grandstand plate was analyzed by consider the influence of different closure time of the post-pouring belt. The induced joint was adopted to guide the structure to crack at the joint and further release the thermal stress. Aiming at the problems of discontinuous reinforcement and complex construction of conventional induced joints, a novel type of concrete induced joint structure with S-shaped bending steel bar was proposed, the calculation method of the maximum spacing of induced joint was determined, and the bending steel bar was measured in the field. The results show that the concrete at the induced joint first cracks, which can further release the thermal stress. The steel bar at the induced joint has a greater demand for deformation, and the configuration of bending steel bar can make full use of its deformation capacity.