Collapse of the spatial double-layer cylinder shell by experimental study

In order to analyze the performance of large-span spatial structures made of new building materials, improve the seismic resistance of large-span spatial structures made of new building materials, analyze the random vibration of large-span spatial structures made of new building materials, and determine the mechanical properties of large-span spatial structures made of new building materials. The paper takes carbon fiber reinforced polymer (CFRP) as an example, and prepares CFRP large-span structural specimens through surface coating treatment of carbon fiber and composite material preparation process; Enhancement effect of interfacial bonding strength of CFRP large-span spatial structures through bidirectional shear experiments; Design large-span spatial structures of carbon fiber composite buildings and establish multi-scale finite element models of vibration reduction systems; Analyze the random vibration of large-span spatial structures, improve the Kanai Tajimi model through the random vibration power spectral density function, calculate the structural response power spectrum, analyze the response of CFRP large-span spatial structures through the H-V coherence function model, and verify the mechanical properties of CFRP material large-span spatial structure specimens through experiments. The test results show that after the tensile test, the CFRP specimen connecting plate did not fail, indicating that the CFRP specimen has a significant impact on its connection strength in this situation. However, the compression and shear failure of the CFRP large-span spatial structure specimen will occur in local areas due to the compressive action of the specimen.

In the identification process of SSI–DATA method, the stabilization diagram is generally used to determine the order of the system. However, in the modal parameter identification of spatial grid structure, there are few stable points that meet the requirements, and the stability axis is not obvious. So, the location of the modal stability point cannot be determined. Furthermore, the QR decomposition of the Hankel matrix is computationally inefficient and difficult to use for online identification when analyzing the spatial structure. In order to solve the above problems, this paper proposes a time-saving random subspace method of spatial grid structure based on an improved stabilization diagram. On the basis of the traditional random subspace method, the projection of the Hankel matrix is transformed into the projection transformation of its R matrix, and then the subsequent calculation is carried out. Then, the frequency search domain is set and the auxiliary stability axis is made. According to the spectrum peak, stabilization diagram and the auxiliary stability axis, the position of the stability axis is comprehensively judged. The modal parameters of the structure can be identified more accurately, which improves the calculation efficiency and avoids modal omissions or misjudgments to a certain extent. Using a spatial structure model (upper chord [Formula: see text][Formula: see text]m, lower chord [Formula: see text][Formula: see text]m, grid [Formula: see text][Formula: see text]m), the advantages of this method were compared and verified. The results indicate that the calculation time of the traditional SSI–DATA method is 29.077[Formula: see text]s, while the improved calculation time is 3.752[Formula: see text]s, resulting in an 87.1% improvement in calculation efficiency, while also preventing mode omission and misjudgment. By further applying this method to vibration monitoring of spatial grid structure hangars, its applicability, higher computational efficiency, and precision have been proven.

Substructure hybrid test examining the seismic response of point-supported glass façades attached to large-span spatial steel structures

Associations among trauma exposure, post-traumatic stress disorder, and depression symptoms in adolescent survivors of the 2013 Lushan earthquake

On 20 April 2013, an Mw 6.6 Lushan earthquake occurred on the southwestern segment of the Longmen Shan fault belt, which is the tectonic block boundary between the eastern Tibetan plateau and the Sichuan basin. Seismic reflection profiles and aftershock relocation indicate that there exists a back thrust fault in the source region but whether it is ruptured during the Lushan earthquake remains controversial. Here the precise leveling data are firstly used together with Global Positioning System (GPS), Interferometric Synthetic Aperture Radar (InSAR), and strong motion data to invert for the fault geometry and slip distribution associated with the earthquake. The joint inversion result shows that the Lushan earthquake occurred on a blind thrust fault with strike N208.5 °E and dip 42.1° to the NW and did not rupture the back reverse fault. The coseismic slip model reveals the Lushan earthquake involves the rupture of one major asperity. The coseismic slip is mainly concentrated on a steeply dipping fault plane. The coseismic rupture terminates on the southwestern side of the seismic gap between the Wenchuan and Lushan earthquakes. Topographic stress may be the dominant mechanism of coseismic rupture termination.

With the development of science and technology in recent years, the large-span spatial structures is one of the fastest growing form of the structure. Because large-span spatial structures are very complex and the construction cycle is long, the impact of internal forces and deformation is relatively large for construction of structures. The constructional mechanic combines structure mechanic and construction technology together, the large-span steel structure construction′ s process simulation must be done to make use of mechanical methods of construction. And it is necessary to take reasonable construction procedures to guarantee the stress and deformation of the construction-completed structure to meet the requirement given by designers. In this paper, the analytical methods and the construction schemes have been discussed by some practical projects on the large-span steel structure, in order to provide a reasonable basis for the construction.

Teachers and students often suffer from the same disaster. The prevalence of PTSD in students has been given great attention. However, in acting as mentors to students and their families, teachers are more likely to have vicarious and indirect exposure via hearing stories of their aftermath and witnessing the consequences of traumatic events. There are limited data pertaining to the prevalence of PTSD and its risk factors among teachers. A total of 316 teachers from 21 primary and secondary schools in Baoxing County were administered a project-developed questionnaire which included the items regarding demographic characteristics, earthquake-related experiences, somatic discomforts, emotional reactions, support status, and everyday functioning 2 weeks after the Lushan earthquake, and they finished a 1-to-1 telephone interview for addressing the PTSD criteria of the Mini International Neuropsychiatric Interview (MINI) 3 months after the earthquake. The prevalence of PTSD was 24.4% among teachers. Somatic discomforts (odds ratio [OR] 1.89, 95% confidence interval [CI] 1.06–3.37) were positive risk factors of PTSD. Perceived social support (OR 0.30, 95% CI 0.14–0.62) and being able to calm down (OR 0.25, 95% CI 0.09–0.75) in teaching were negative risk factors. PTSD is commonly seen among teachers after an earthquake, and risk factors of PTSD were identified. These findings may help those providing psychological health programs to find the teachers who are at high risk of PTSD in schools after an earthquake in China.

Seismic design and inelastic seismic response of lumped mass mdof dual structure

Columns are the primary load carrying members in buildings and bridges. Hence for better seismic performances the permanent drift after severe earthquake has to be reduced to make the structure functional with less maintenance. The use of the shape memory alloys in critical region can reduce the residual displacement due to its super-elastic nature. Super-elastic shape memory alloy bars have higher linear elastic range of 4–12% and can return back to its initial shape upon removal of load. In this numerical study full scale circular column with various types of nickel, iron and copper based shape memory alloy (SMA) bars in the critical region under reverse cyclic loading with constant axial load of 10%. The seismic performance of the SMA-steel reinforced column was compared with the steel reinforced normal column. The column reinforced with FeMnAlNi SMA in critical region shows better seismic performance considering load carrying capacity, displacement ductility, maximum displacement, lesser permanent deformation and energy dissipation capacity.

The study analyzes the seismic performance of spatial steel frame structures by creating a three-dimensional nonlinear finite element model and designing vibration table model experiments. This is done to ensure the seismic performance of the steel framing-bracing system in spatial steel frame structures and to raise the level of seismic and disaster prevention technology of steel structures. The outcomes revealed that under the experimental load consisting of simulated seismic waves generated by the shaker, the initial natural frequencies of the bidirectional bracing arrangement in white noise in the X and Y-directions were larger, 53.18 Hz and 72.49 Hz, respectively. The decrease of the vibration frequency of the bidirectional bracing arrangement structure was smaller under the increase of the excitation acceleration. In El Centro seismic waves, Taft seismic waves and Wenchuan seismic waves, the changes of damping ratio, acceleration amplification factor and relative displacement of bidirectional bracing arrangement were smaller than those of unidirectional bracing arrangement. The bidirectional bracing was beneficial to the overall stiffness and seismic performance of the structure, and helps the steel frame structure to resist lateral displacement. At the same time, the bidirectional support was more favorable to the seismic performance if the support structure was arranged according to the wave, which could effectively reduce the strain. Under the simulated seismic action of the 3D non-linear finite element model, the finite element model results were tested by inputting the parameters of Wenchuan seismic wave, the fit between the finite element model results and the vibration table experiment results was high, and the acceleration time-course curve and displacement time-course curve were basically the same. The simulation errors of the maximum values of acceleration and displacement were 7.0% and 4.0%, and some of the larger errors were within the acceptable error range. This study provides reference and theoretical guidance for the research on the seismic performance of steel framing - bracing system under seismic action, which is conducive to the expansion of the application field of steel seismic structures.

A risk-averse distributionally robust optimisation approach for drone-supported relief facility location problem

The influence of professionals on the general public in the choice of earthquake disaster preparedness: Based on the perspective of peer effects

Large-span wooden spatial structures in the form of domes, developed in JSC Research Center of Construction under the leadership of A.A. Pogoreltsev, are built in large numbers for roofing various buildings. Such designs have high performance indicators and continue to improve. In 2020 the Manual on accounting for the joint work of the frame and fencing in wooden spatial structures of buildings and structures was developed as an addition to SP 64.13330.2017, containing examples of strength calculation and optimization of rib cross-section dimensions, as well as an example of determining the long-term strength of the shell cladding. These structures, in fact unique, are designed so far in the margin of safety without taking into account the participation of the enclosing part (panels, decking, etc.) in the bearing loads. Taking into account the work of the decking, especially when exposed to asymmetric loads, can lead to material savings. In addition to the above theory of nonlinear shell calculation, the authors have also developed a calculation of composite anisotropic panels operating under complex stress conditions, i.e. under biaxial compression (tension) and shear. The calculation of such structures under both short-term and long-term loads presents certain difficulties and requires the introduction of strength theories and criteria for their description that are unusual for specialists of design organizations.

Recently, high-strength 7075-T6 aluminum alloy has demonstrated promising application prospects in large-span spatial structures given its exceptional mechanical properties. However, the classical Ramberg–Osgood (R–O) constitutive model cannot accurately predict the mechanical behavior of 7075-T6 aluminum alloy in the large-strain stage, compromising the structural reliability of designs. Herein, the full-range stress–strain curves of 7075-T6 aluminum alloy were investigated through tensile tests. Mechanical property indices were obtained, and the classical R–O model was calibrated for 7075-T6 aluminum alloy. Furthermore, an improved R–O model based on piecewise functions was proposed to address the significant prediction errors under large-strain conditions (ε > 0.015). Compared with the classical R–O model, the modified model exhibited a reduction of over 75% in stress–strain curve deviation. Moreover, an approximate value method only based on nonproportional extension strength and elastic modulus was proposed for the calibration of the modified model, considerably enhancing the engineering practicality of the modified constitutive model.

Global stability analysis cannot be ignored for large-span spatial steel structures. Beijing Jiangtai Winter Garden adopts hybrid structure with latticed shell and vertical cables, on which glass curtain wall is fixed. Therein the reticulated shell is composed of 9 spatial arches and other common frames, thus it can be seen as arch-reticulated shell hybrid structure. This paper analyzes the stability of one single arch structure which has the largest span in the whole structure, including buckling analyses and non-linear full range analyses. The results show that the stability of single arch meets requirements, and the nonlinearity has great influence on the stability of single arch structure. Besides, although the initial geometric imperfection has certain effect on the elastic structure, it has little effect on the elasto-plastic one.