Rare Earthquake Research Articles

Shaking table tests on 0.5-scale multistory models of plate-type modular steel and composite buildings with semi-rigid corner connections

To study the dynamic properties and seismic response of global plate-type modular steel and composite structures with semi-rigid corner connections, shaking table tests were conducted on three 0.5-scale multistory plate-type modular models. This paper presents the testing program and results, including the dynamic characteristics and earthquake performance. Under the excitation of seismic loads, the bolts connected to the corners were easily loosened, the gaps between the composite wall plates increased, and the concrete surface layer of doorways and windows was damaged and fell off. The test results showed that as the peak ground acceleration increased, the fundamental frequency decreased, the damping ratio increased, and the acceleration amplification factor decreased. The initial lateral stiffness of plate-type modular composite structures with wall panels was eight to nine times that of plate-type steel frame structures owing to the strong skin effect of the wall panels. The stiffness of complete composite structures decreased by approximately 50% under a nine-degree rare seismic intensity owing to the deterioration of the bolt rotation stiffness and damage to the wall panel. The maximum interstory drifts of the complete plate-type modular building under rare earthquakes were small, which meets the requirements of the seismic design code.

A Seismic Fragility Assessment Method for Urban Function Spatial Units: A Case Study of Xuzhou City

Cities that experience earthquake disasters face a lot of uncertainties and unsustainability resulting from the fragility of their infrastructure, which should be considered in engineering. This study proposes a seismic fragility assessment framework for urban functional spatial units in order to improve the traditional structural fragility assessment criteria that are currently applied in urban planning. First, appropriate spatial units are classified for the study area, the functional categories of the study area are determined using urban Point of Interest (POI) data, and the functional proportion of the spatial units is calculated. Secondly, considering the classification of different seismic fortification levels represented by different construction ages, and considering the possible building forms and HAZUS’s classification system of building structures in order to establish the correlation between building functions and building structures, the methods of a field survey and a questionnaire survey are adopted to match the functions with the most likely building structures. After this, based on the assumption of the lognormal distribution of ground motion intensity, a mixed method is adopted to calculate the mean value μ¯ for the fragility of functional space units. The Monte Carlo method is then used to discretize the data and statistically obtain the standard deviation β¯ for the fragility of functional space units, and the fragility curve is then fitted. A district in Xuzhou City, China, was used as a case study to verify this assessment framework. The results showed that: (1) the fragility of functional space units was greatly affected by the proportion of defense standards in different periods in the unit, which reflected the average level of fragility within the unit. (2) The unit loss index of units built after 2001 with a proportion of less than 50% is basically above the average loss level of the study area. (3) The simulated damage ratio of the assessment results under the three levels, namely frequent earthquake, fortified earthquake and rare earthquake, is consistent with the previously experienced earthquake damage. The paper concludes that it is helpful to design and utilize seismic fragility predicting formulas and technologies at the functional spatial unit level for urban planning, which is meaningful for the formulation of planning strategies, reducing risks to infrastructure and delivering sustainable development.

Seismic Performance Comparison of Three-Type 800 m Spherical Mega-Latticed Structure City Domes

With changes in the city environment and advances in engineering technologies, there is an increasing demand for the construction of super-large span city domes that can cover a large area to create a small internal environment within a specific region. However, the structural design must overcome various challenges in order to break the current structural span limitations. Moreover, there is little research on structures achieving such large spans. The seismic performance of the selected Kiewitt-type, Geodesic-type, and Three-dimensional grid-type mega-latticed structures is further investigated upon previous studies of the model selection, static and stability analysis results of the 800 m span mega-latticed structures. Finite element models were established with ANSYS to analyze the modal properties and earthquake response of the structures. The study evaluated the impact of earthquake directionality on the structural response as well as the response pattern of the structure under frequent and rare earthquake actions. It was found that the overall integrity of the structures is good, with strong coupling effects in three directions. The multi-dimensional seismic input method should be applied to solve the structural response. Combining the plastic development of the structure under rare earthquakes, the top and the circumferential trusses of the third and fourth rings are relatively weak parts of the structures. According to this study, given the known static analysis results, the maximum displacement and maximum stress of the structures under frequent and rare earthquake actions can be estimated. Furthermore, the study highlights that Three-dimensional grid-type mega-latticed structures should be prioritized designing structures with spans of 800 m, providing helpful guidance for the practical application of this type of structure.

Running safety assessment of trains considering post-earthquake damage state of bridge–track system

A bridge–track system (BTS) is inevitably damaged during an earthquake; this is reflected in its stiffness deterioration and residual deformation, which affect the post-earthquake running safety of trains. The influence of the post-earthquake damage state of an actual BTS on train running safety remains unclear. Hence, this study mainly discussed the influence of post-earthquake bridge–track damage state and residual deformation on running safety and established a safe speed limit for trains under different seismic intensities. A finite element (FE) model of a simply supported railway BTS was established using the OpenSees software. A nonlinear seismic response analysis was performed under different ground motion intensities (0.1, 0.3, and 0.6 g for frequent, design, and rare earthquakes, respectively), and bridge damage, fastener damage, and residual deformation of the rail after the earthquakes were studied. An OpenSees-TRBF (train-rail-bridge-foundation coupled system dynamic analysis software, TRBF) co-simulation method was developed to analyze the running safety of trains after earthquakes under a damaged state of the BTS based on the TCP/IP communication interaction technology. A safe speed limit for trains considering the post-earthquake damage state and residual deformation was proposed, providing a reference for the post-earthquake capacity of trains. The results of the BTS seismic damage analysis showed that the residual displacement of the bearing was the fundamental reason for the change in the rail line shape, and fastener damage mainly occurred in the range of 2–4 fasteners at the end of the girder under the design and rare earthquakes. The results of the running safety analysis showed that, if damage to the BTS is ignored, the running safety after an earthquake will be misjudged. Based on the continuous overrun time limit index, the running safety indices for ground motion intensities of 0–0.4, 0.4–0.5, and 0.5–0.6 g could meet the speed requirements of 350, 300, and 150 km/h, respectively. This study provides some references and suggestions for the running safety of trains following an earthquake.

Adaptability of precast concrete external wall panels to steel frame deformation with flexible connectors

A cantilever holder–girth (CHG) flexible connector was proposed for improving the adaptability of precast concrete (PC) external wall panels to the deformation of the steel frame under severe seismic loads. Three specimens of full-size single-span two-story steel frames with PC external wall panels (composite, open-window, and integral) were designed and tested. Low cyclic loading was applied to the steel frame, and a horizontal force was applied to the external wall panels as inertial force. The results showed that the external wall panels with flexible connectors had good adaptability to the deformation of the steel frame. The maximum deformation of the CHG flexible connector reached 27.16 mm even when the external wall panels were subjected to rare earthquakes such as a magnitude 9 earthquake. The displacement angle of the external wall panels was only 0.0026 rad when the steel frame reached a 2.4 % story drift angle.

Mechanical Properties and Seismic Loss Assessment of Improved Isolation Bearing with Variable Stiffness

For improving the seismic isolation effect, traditional rubber isolation bearing provides a smaller horizontal stiffness. However, it is unfavorable for the displacement control of the seismic isolation layer under rare earthquakes. In this paper, an improved lead-core rubber isolation bearing is proposed. The improved isolation bearing can provide a small horizontal stiffness to enhance the seismic isolation effect under small earthquakes. Under large earthquakes, it can provide a large horizontal stiffness to prevent over-limit failure due to excessive displacement. The mechanical properties of the improved isolation bearing were investigated using the finite element method (FEM), and the restoring force model of the improved isolation bearing was established. Based on the FEMA P-58 theory, the earthquake loss assessment in terms of repair cost and casualty indexes was carried out for normal frame structures, normal isolation structures, and improved isolation structures. The results show that the improved isolation bearing maintains a smaller horizontal stiffness before the displacement is limited, giving full play to the isolation performance. After that, the horizontal stiffness of the bearing is enhanced, which can effectively control the displacement of the seismic isolation layer. The lead-core can give full play to the energy dissipation characteristics. Under the four performance levels, the improved isolation structure has the highest safety reserve and the best collapse resistance. The use of improved isolation bearings can reduce the repair cost of the structure and casualties.

Mechanical Analysis of Junction Pier of Fuzhou-Xiamen High-Speed Railway Rigid-Frame Bridge

The continuous rigid structure bridge on both sides of the Quanzhou Bay Crossing Bridge uses double-limbed thin-walled flexible piers for the junction piers between the links, and the whole bridge has no bearings. In China, the monolithic bearing-free prestressed concrete continuous rigid-frame bridge is used in railway bridges. The junction pier between the two adjacent couplets is a double-leg thin-walled flexible pier. The single leg thin-walled pier is connected with half of the pier-top segment. During the construction process, the block with numbered zero on the top of the pier is temporarily anchored and connected. Symmetrical cantilevered baskets are used on both sides for construction, and after the mid-pier cantilevered construction is completed, the temporary anchoring device for the block with numbered zero is removed. Because the structural system conversion is required in the construction, the mechanical properties of the junction pier will change greatly before and after the conversion, so it is very necessary to calculate and analyze it to master. In this paper, the finite element model of the connecting pier is established accurately, the stress and deformation of each part of the connecting pier under unfavorable working conditions is analyzed in detail, the seismic spectrum analysis under the action of common earthquake and rare earthquake is carried out, and the stress and deformation law of the structure is expounded, which can provide some reference for the construction of similar projects in the future.

Seismic Performance Analysis of Conjoined Structures with Inhomogeneous Stiffness Distribution

<p>Two or more independent towers are joined together through a connectome to form a conjoined structure. The deformation and internal force of the tower are complex, and the coupling effect between the two towers is remarkable when the earthquake is subjected. In this paper, elastic -plastic time -history analysis is adopted to research the dynamic dynamic response under the action of rare earthquakes. Moreover, in order to analyze the influence of symmetry and span parameters on the dynamic response of structures, elastic-plastic time-history analysis is carried out on structures with different symmetries, different stiffness distributions in planes and different spans.</p>

Seismic performance of RC frames with self-centering precast post-tensioned connections considering the effect of infill walls

This paper presents the seismic performance evaluation of self-centering precast post-tensioned concrete (SCPPTC) frames with infill walls. The SCPPTC connection system consists of all-steel bamboo-shaped energy dissipaters (SBED) and prestressed tendons, which provide energy dissipation capacity and self-centering capability, respectively. Using modeling parameters calibrated with experimental tests, nonlinear numerical models of SBED, SCPPTC connection, infill walls, and 2D SCPPTC frames were developed in OpenSees, to compare the performance of the structures with different types of infill wall layouts. Nonlinear static pushover and incremental dynamic analysis (IDA) were performed to study the effect of infill walls on the overall response of SCPPTC frames, in terms of stiffness, strength, maximum interstory drift ratio,θmax, the maximum residual interstory drift ratio, θr,max, and the normalized post-tensioned force. Using the IDA results, the study also developed fragility curves and estimated the collapse margin ratios. The results demonstrated that the shear strength of the SCPPTC frame was improved from 4.19% to 12.2%, and the initial secant stiffness of the SCPPTC frame was augmented from 22.9% to 88.3% with increasing filling rate. The totally infilled SCPPTC frame (SCPPTC-ToI) exhibits a 19.86% lower θmax than that of pilotis-infilled SCPPTC frame (SCPPTC-PiI) under rare earthquakes, and the maximum prestress of SCPPTC-ToI was also 7.14% lower than that of SCPPTC-PiI. With the increase in filling rate, θr,max increased by a maximum of 120.45%. The pronounced soft layer led to the highest failure and collapse probabilities of SCPPTC-PiI among all SCPPTC frames at the same performance level.

Structural Design and Analysis of a Super-High Building in Nanjing, China

This study analyzes a high-rise building with B-level height (i.e., a total height of 146.5 m) and a shear wall structure. Since the project contains many plane irregularities (including 1a torsional irregularity, 1b eccentric arrangement, and 2a plane convex irregularity), it should be treated as a super high-rise building. This study introduces the main characteristics and overrun conditions of the project and describes the structural design of the foundation and the basement, upper structural layout, force conditions under frequent, fortified, and rare earthquake actions, and structural performance-based objectives in detail. The following measures can be adopted to address the overrun problem. First, the floor at the thin waist of the structure was thickened to 150 mm and reinforced in the bilayer and bidirectional patterns, with a reinforcement ratio of no less than 0.25%. The damage condition on the floors under a great earthquake was analyzed. The vertical components at the waist were reinforced to constrain the extension of the edge components toward the top. Second, the structure’s peripheral stiffness was strengthened to enhance the anti-torsional performance and minimize the adverse effects on torsional irregularities. Third, using two software programs, the performance-based envelope design under medium earthquake action and dynamic elastoplastic analysis under great earthquake action were analyzed to ensure structural safety. Fourth, the edge components were constrained for the shear wall columns with axial-to-compressive stress strength ratios exceeding 0.3. For the overall structure and critical parts, force conditions under frequent, fortified, and rare earthquake conditions were calculated and examined with the SATWE, MIDAS GEN, and SAUSAGE software packages. The calculation results revealed that the structure shows favorable anti-seismic performance, with an overall anti-seismic C-level and a safe and reliable structure. The structural design method introduced in this article can promote the sustainable development of structural design.

Investigation on Seismic Performance of the Fully Assembled Steel Frame Applying Beam-Column Joints with Replaceable Energy-Dissipating Elements

Based on the application of a beam-column joint with replaceable energy-dissipating elements and hinged beam-column proposed by the author, the seismic performance of a fully assembled steel frame with this joint was investigated in this paper. Through two projects of a traditional steel frame (TSF) and an assembled steel frame applying beam-column joints with replaceable energy-dissipating elements (ASFWREE) and their numerical simulation calculation by SAP2000, the main structural design indicators such as natural vibration period, period ratio, mass participation coefficient, base shear force, inter-story displacement angle, rigid-weight ratio, and shear-weight ratio of two frames under frequent earthquake, and their influence factors were compared and analyzed. By carrying out the elastic–plastic dynamic time–history analysis of two projects under a rare earthquake, the maximum inter-story displacement angle, base shear force, stiffness between floors, maximum vertex displacement, and the occurrence sequence and distribution of plastic hinges of the two items were compared. The results show that the deformation of ASFWREE had the characteristics of the shear deformation of TSF and the deviation of the natural vibration period was less than 5% when the ratio of the linear stiffness of the energy-dissipating element to the steel beam was approximately 0.8, the ratio of horizontal length to span was about 0.25, which was close to the strength grade of the steel beam. The seismic performance under the rare earthquake was close to or higher to that of the TSF, can ensure that the beam and column are not damaged, and the structure does not collapse. The failure mode of the ASFWREE is consistent with the experimental research of the beam-column joints.

Longitudinal Seismic Analysis of Tunnels with Nonuniform Strata Considering the Effect of Karst

The longitudinal direction of shield tunnels is prone to seismic damage due to excessive deformation under seismic action, especially in nonuniform stratum. In this paper, the longitudinal dynamic response of the tunnel under different seismic effects is calculated based on the longitudinal equivalent stiffness model using the stratigraphic load model, and the seismic indexes such as longitudinal corner, tube sheet and joint bolt stresses are verified. The calculation results show that the longitudinal seismic weakness of the shield tunnel is in the interface between soft and hard strata and karst development. The longitudinal axial force of the structure is larger during the longitudinal excitation of seismic waves, and the maximum bending moment is mainly in the vertical plane, i.e., the vertical bending moment. The axial force of the tunnel is smaller during the transverse excitation of seismic waves. The maximum bending moment is mainly the bending moment in the horizontal plane, i.e., the transverse moment. The South Lake section of the Two Lakes Tunnel has good seismic performance in the event of a rare earthquake with a 50-year exceedance probability of 2%. The investigation can guide the seismic design of the South Lake section of the Two Lakes Tunnel.

Reliability analysis of an inter-story isolated structure under a main-aftershock sequence based on the Laplace asymptotic method

After a strong mainshock, subsequent ground motion is the result of a sequence of multiple aftershocks, and the damage to a structure under these conditions is more severe than from a single earthquake. Most seismic studies are based on a single earthquake event. To explore the influence of a main-aftershock sequence on an isolated inter-story structure, we constructed a three-dimensional finite-element model of such a structure and subjected it to repeated main-aftershock sequences. The Laplace asymptotic method of second-order second-moment was used to calculate the reliability of the structure under the action of a single mainshock and after a main-aftershock sequence at different seismic levels. The effects of the number of aftershocks, the location of the isolation layer, and the stiffness of the isolation bearing in the structure were analyzed. The results showed that aftershocks increased the failure probability of each sub-structural part of the inter-story isolated structure. The failure probability of the lower structure had the greatest influence, which was about 3.89 times that for the mainshock alone. The probability of failure from multiple vs single aftershocks was similar, but the magnitude of the aftershock plays a major role in failure. The number of aftershocks reduced the overall reliability of an inter-story isolation structure. In the case of different isolation layer positions, the placement of the isolation layer at the top of the seventh story under an extremely rare earthquake level resulted in a reduction of 6.01%. With isolation bearings of different stiffness, the largest decrease was 7.88% when the stiffness was 50%.

Seismic performance of damaged frame retrofitted with self-centering and energy-dissipating rocking wall

This paper proposes the novel concept of retrofitting damaged reinforced concrete frame with self-centering and energy-dissipating rocking wall. Parametric studies were carried out base on pushover and time-history analysis. In both pushover and time-history analysis, the soft-story mechanism was effectively mitigated through the rocking wall retrofit of the damaged structures. The results demonstrated that the stiffness and bearing capacity of the retrofitted system were improved compare to its intact state. Additionally, the seismic response of the damaged frame retrofitted using rocking wall in combination with post-tension and shear-type damper fell within the relevant design limits. Pushover analysis of the rocking wall indicated that there is a linear relationship between the wall thickness and the initial stiffness of the retrofitted system. The addition of post-tension tendon to the rocking wall system enables the wall to self-center and increases lateral stiffness and bearing capacity of the retrofitted system. When the shear-type damper was installed, the energy dissipation of the system was increased, and the stiffness and bearing capacity of the retrofitted system were also improved. In the time-history analysis, it was found that the thickness of the rocking wall is directly related to the maximum inter-story drift and the distribution patterns of inter-story drift of the frame. As the post-tension was added to the system, the maximum inter-story drift under rare earthquake excitation improved significantly. With the addition of shear-type dampers, the overall drift magnitude of the retrofitted system was fundamentally decreased.

Cyclic Response of Sloped Extended End-Plate Moment Connections

Bolted extended end-plate (BEEP) moment connections are extensively recommended in design standards to be used as a prequalified beam-to-column connection in steel portal frames and special moment frame buildings. These standards assume that in such a connection, the beam is perpendicular to the steel column or that the slope angle of the steel beam is very small. To expand the engineering applications of BEEP connections in large-slope angle buildings, in this study, three one-sided specimens at half scale with 0°, 15°, and 30° slope angles, respectively, were designed and tested under cyclic loading. All dimensions of these specimens were identical, except the slope angles of their steel beams. The experimental results showed that the maximum rotation angles of these sloped BEEP connections exceeded 0.05 rad, and they were remarkably larger than those of other types of sloped rigid-moment connections tested by Mashayekh and Uang. However, the force concentration that occurred in the flange at the heel location was similar to that observed by them, and it led to the development of brittle fractures. Particularly, with the increase in the slope angle, the force concentration tended to become more severe. Three strengthening schemes for reducing the force concentration and enhancing the deformation capacities of the sloped BEEP connections subjected to the extremely rare earthquake, i.e., less than 2% probability of exceedance in 50 years, were evaluated using the finite element approach. These were Scheme I: stiffening the rib in the acute-angle zone, Scheme II: employing a reduced beam section (RBS) connection, and Scheme III: forming a curved web cut in a non-RBS beam. The analytical results showed that the three schemes decreased the von Mises stress level in the acute-angle zone of the connection web. Scheme I enhanced the initial rotation stiffness, flexural strength, and deformation rotation capacity. For Scheme II, a RBS configuration was employed, which effectively improved the connection rotation capacity, whereas it decreased the flexural strength of the sloped BEEP connection. Scheme III without a reasonable design led to a degradation of the hysteretic performance, moderate rotation capacity, and low flexural strength. Therefore, Schemes I and II leading to much better seismic behavior than Scheme III are recommended.

Hysteretic model and seismic energy response of CFST columns in diagrid structure

The mechanical performance of the diagrid concrete filled steel tubular (CFST) columns is significantly different from that of the traditional bending components, and very few research has been conducted on their hysteretic performance. In this study, the axial cyclic test results of eight CFST columns were presented. Based on the experimental results, the degenerate trilinear model was used to establish the dimensionless skeleton curve model, and the calculation formulas for the peak bearing capacity and the corresponding displacement of the CFST columns were proposed. On account of the observed damage characteristics of the CFST columns, different hysteretic rules were selected to establish the unloading stiffness functions in the tension and compression directions. Thus, a hysteretic model suitable for CFST columns under axial cyclic loading was proposed, and the rationality of the hysteretic model was verified by comparison with the test results. Afterwards a refined finite element model of the diagrid structure was established using the proposed hysteretic model of the CFST columns. Through elastic–plastic time history analysis, the energy distribution of the diagrid structure was studied, and the interlayer distribution of the inclined CFST columns under rare earthquakes was analyzed. The results shown that the energy had an obvious mutation at the junction between the bottom module and the secondary node layer, so it is necessary to avoid large stiffness mutations in the design of the diagrid structure.

Diagrid Core-tube Structure Seismic Performance Based on Equivalent Stiffness Ratio of Inner and Outer Tubes

To study the relationship between the stiffness ratio of the inner and outer tube of the diagrid core-tube structure of high-rise buildings and the redistribution of the storey shear force, the structural ductility, overstrength factor and the seismic performance, a total of 12 kinds of diagrid core-tube structures of equivalent stiffness ratios were established at 71°, 77° and 80° diagonal angles. Based on the static pushover analysis method, combined with the principle of capacity spectrum and demand spectrum, the characteristics and laws of the position change of the weak layer, the redistribution of the storey shear force, the shear lag effect of the bottom compression flange and the overall ductility of the structure are analyzed under the action of the frequent earthquake (70 gal), fortification earthquake (200 gal), rare earthquake (400 gal), extremely rare earthquake (510 gal) and huge earthquake (620 gal). The results show that under different earthquake actions, there is an obvious redistribution of floor shear force in the diagrid core-tube structure, and the storey shear coefficient decreases with the increase of earthquake level and equivalent stiffness ratio. The diagonal angle is the main factor affecting the location of the weak floor and the shear lag effect. The shear lag effect of the structure increases with the increase of the seismic fortification level. The structural ductility with a diagonal angle of 77° is generally optimal. When the equivalent stiffness ratio is 0.64, the structural ductility reaches the optimal value of 1.46, which is 1.1 times that of 71° and 80° diagonal angles. In the structure with the same diagonal angle, the overstrength factor increases with the increase of the equivalent stiffness ratio.

Hybrid Test of Precast Concrete Frame with Energy-Dissipation Cladding Panel System

To investigate the influence of an energy-dissipation cladding panel system (EDCPS) on the dynamic responses of a precast concrete (PC) frame structure, a six-story, three-span planar frame structure with an EDCPS (called “damping structure”) and a counterpart planar bare frame structure (called “bare frame structure”) were designed. The middle span and bottom two stories of the frame were selected as the test substructures, whereas the rest were considered using the numerical substructure. Hybrid tests were conducted on the two structures under four earthquake levels. The test results indicated that the damage evolution characteristics of the PC frame were not affected by the introduction of EDCPS. The dampers in the EDCPS successfully yielded and dissipated seismic energy under the four earthquake levels. Moreover, the maximum inter-story drift ratio of the damping structure was reduced by 12.59%, 17.68%, and 10.34% under the design-basis earthquake, maximum considered earthquake, and very rare earthquake, respectively, exhibiting a satisfactory damage-control effect. The cladding panels remained intact under the four earthquake levels, indicating that this structure effectively prevents damage to the cladding panels. Finally, a numerical simulation method is recommended according to the damage characteristics of the damping structure and is validated against the test data.

Shaking table test on suspend-dome structure with the center-hung scoreboard under three-dimensional seismic

In order to meet the demand of watching games, the LED display, i.e., the center-hung scoreboard, has been widely used in large stadiums. To investigate the mechanical properties of the suspend-dome structure with the center-hung scoreboard under the action of earthquake, a dynamic scaled model with a geometric similarity ratio of 1:20 was designed. And the shaking table test was performed to study the seismic performance under the actions of 8 degree frequent, seismic precautionary and rare earthquakes. The acceleration, displacement and internal force responses under three-dimensional seismic were analyzed. The results show that the Z-directional acceleration amplification factors of the reticulated shell vertex region are significant and decrease fastest under actions of rare earthquakes, which is the weak point of the model. The influence of the center-hung scoreboard on the structure cannot be ignored in the study of seismic performance. The vertical displacement is the largest in the center and gradually decreases from inside to outside. The maximum displacement under actions of frequent earthquakes is 2.061 mm. The maximum displacement under actions of seismic precautionary earthquakes is 1/556, the maximum displacement under actions of rare earthquakes is 1/242, both of which satisfy the requirement of seismic specifications. The maximum internal force of the ring rod first decreases and then increases from the center to the surroundings. The internal force of the radial rod gradually increases from the edge to the center. Under actions of rare earthquakes, the center-hung scoreboard has more influence on the internal force of the rod. The accuracy of the finite element modeling method is verified by comparing the simulation results and test results of the scaled model, and the reliability of the scaled model is verified by comparing the simulation results of the scaled model and the prototype structure. The structure does not collapse under actions of 8 degree rare earthquakes and does not show apparent failure. The seismic principle that “the structure hasn’t damaged under frequent earthquake, repairable under precautionary earthquake, and doesn’t collapse under rare earthquake” is reached, thus the structural design of the Lanzhou Olympic Sports Complex is reasonable.

Research on seismic performance of honeycomb plate cylindrical reticulated shell structure

In previous research, an aluminum alloy honeycomb plate cylindrical reticulated shell structure was designed. The bearing capacity test and numerical analysis show that the numerical analysis model of honeycomb plate cylindrical reticulated shell structure is reliable. In this paper, the seismic performance of the honeycomb plate cylindrical reticulated shell structure was investigated by modal analysis and time-procedure analysis. The results show that the low-order vibration modes of the cylindrical reticulated shell structure are generally dominated by lateral translational, plane torsional or vertical vibration. The natural frequency of cylindrical reticulated shell structure with bottom plate is greater than that of cylindrical reticulated shell structure without bottom plate, which has more reasonable mass, stiffness distribution. The cylindrical reticulated shell structure with bottom plate has better seismic performance, and its deformation under rare earthquake meets the specification requirements.