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Large capacity tanks storing various liquids are important components in distribution and transmission systems. During operation tanks can be subjected to different types of loading. Therefore, maximum attention must be paid to the tank design to capture all possible causes and forms of failures. The article deals with the procedure for seismic resistance of liquid storage tanks which are in accordance with the principles of Eurocode 8 standard. The seismic analysis is performed on flexible (steel) circular vertical ground-supported model of tank containing liquid (water). The main aim is to determine basic seismic characteristics, distributions of hydrodynamic pressure, dynamic properties and response of investigated tank-liquid system subjected to earthquake excitation (El Centro). Seismic analysis and results comparison are carried out on mechanical spring-mass model (Eurocode 8) and finite element model (ANSYS).

The consequences of destructive earthquakes show that the problem of analyzing the response of reinforced concrete frames under seismic loads after a fire is relevant. The calculation models used for individual elements and buildings as a whole must take into account the nonlinear properties of concrete and reinforcement. In the spectral calculation method, the nonlinear properties of materials are taken into account by introducing a reduction coefficient to the elastic spectrum. When determining the reduction coefficient, a common deformation criterion is based on the use of the plasticity coefficient. The seismic resistance of a three-span, five-story reinforced concrete frame under four different fire exposure options is considered. The residual strength and stiffness of frame elements after a fire is assessed by performing a thermal engineering calculation in the SOLIDWORKS software for a standard fire. For the central sections of the elements, the highest temperatures were obtained after heating—during the cooling stage. The reduction coefficient is estimated by performing a nonlinear static analysis of reinforced concrete frames in OpenSees and constructing load-bearing capacity curves. Fracture patterns and damage levels in plastic hinges are analyzed. Based on the numerical modeling of reinforced concrete frames after exposure to fire, it was revealed that the most dangerous scenario is the occurrence of a fire on the first floor of the building. Based on the obtained plasticity coefficients, reduction coefficients were determined in the range of 2.62 to 2.44. The influence of fire on the permissible damage coefficient of a reinforced concrete frame is assessed using the coefficient φK—the coefficient of additional damage after a fire, which is equal to the ratio of the reduction coefficients for the control and fire-damaged frames. Depending on the percentage of damaged structures on the first floor, the following values were obtained: 50% or less—φK = 1.09; 100%—φK = 1.17. The obtained coefficients are recommended to be used when assessing the seismic resistance of a reinforced concrete frame after a local fire. [ABSTRACT FROM AUTHOR]

Abstract Experimental investigation on seismic performance of RC shear walls reinforced with CFRP bars in boundary elements to enhance the resilience was presented which is expected for stable resistance capacity and small residual deformation. Six RC shear walls reinforced with CFRP bars as longitudinal tensile materials in boundary elements were tested under reversed cyclic lateral loading while subjected to constant axial compression with different axial load ratios of 0.17, 0.26 and 0.33, respectively. Two forms of stirrups were used for each axial load ratio, which were rectangular and circular stirrups in boundary elements. A reference specimen, ordinary RC shear walls, was also introduced to certify the excellence of CFRP bars. The test results indicated that the walls utilizing CFRP bars had small residual deformations and residual crack widths. Lower crack propagation height and larger concrete crushing region, bearing capacity and equivalent viscous damping coefficient (EVDC) could be observed with the increase of axial load ratios. The effects of stirrup forms on experimental results had a relation to the axial load ratio. When the axial load ratio was small, the shear walls with circular stirrups had better energy dissipation than that with rectangular stirrups at a given drift level, while the cumulative energy dissipation (CED) were similar. With the increase of axial load ratio, the walls exhibited similar energy dissipation at the same drift level, however, the shear walls with rectangular stirrups had larger CED.

The paper analyzes the dynamic response of an underground main pipe under the action of a longitudinal wave propagating in soil along the pipe. The article assumes that the elastic pipe is of a finite length, and a linear viscoelastic model of the “pipe-soil” system interaction is considered. The problem is solved numerically using the explicit scheme of the finite difference method. A longitudinal wave in the soil is taken as a traveling sine wave. The article presents a comparative analysis of the results for certain values of elastic and viscous interaction coefficients, propagation velocity, and pulse duration. Under elastic interaction of the “pipe-soil” system, the reflection of the wave propagating in the underground pipeline at the boundaries of the pipeline coincides with the propagating wave in soil, leading to an increase in the maximum deformation of the underground pipeline, the value of which can double. The viscosity coefficient of interaction at the “pipe-soil” system contact leads to attenuation of the wavefront in the underground pipeline. For soils with values of viscous interaction coefficient of more than 100 kN·s/m2, this may lead to complete attenuation of the bursts at the wavefront in the pipeline. The choice of the step ratio in coordinate and time equal to the wave propagation velocity in the pipeline allows for obtaining results that coincide with the exact solution.

A dynamic continuum plate model of a multi-story building is proposed in the form of a cantilevered orthotropic plate, developed in the framework of Timoshenko’s theory of plates, which describes seismic vibrations of buildings. Formulas are given for determining the reduced moduli of elasticity, shear, and density of a plate model of a building. Transverse natural and forced oscillations of a nine-story building under nine-point seismic impacts are considered. Numerical results are obtained.

As a kind of destructive natural disasters, earthquake can cause serious damage to the bridges of lifeline projects, which will bring great difficulties to the rescue and relief work. The bridge structure is complex, and people pay increasingly more attention to the research on its seismic resistance. It is very important for designers and researchers to adopt an appropriate analysis method in seismic resistance analysis. This paper briefly summarizes the hazards caused by earthquakes to long-span bridges, and introduces the calculation principles of response spectrum method and time history analysis in detail. Through the comparative study of the two commonly used seismic resistance analysis methods for bridges, it summarizes the advantages and disadvantages and the application scope of each method, providing reference for selecting suitable design methods for seismic resistance design. Lastly, it describes the future research trends of response spectrum method and time history analysis.

Dry-type joints are an advanced type of sustainable beam-column connection mode used in the prefabricated concrete frame structural system. This paper proposed an improvement scheme for high-strength bolt dry-type joints and designed a new type of common bolt dry-type joints. A pseudo test involving low-cycle repeated loading is conducted to assess the seismic resistance properties of new joints including damage mode, hysteretic curve, skeleton curve, and ductility factor. Numerical simulation is applied to validate the rationality of experimental results. It is found that when the bending capacity of the end block of the beam is consistent with that of the bolt, the deformation of the bolt will no longer increase greatly after a period of large deformation; at this period, the bolt does not fully enter the plastic stage, but at this time, the end block of the beam begins to appear large cracks and enter the plastic deformation and has good energy dissipation performance.

In seismic areas, it is recommended to design bridges characterized by ductile behaviour. A large number of existing bridges designed according to outdated standards, without guidelines for ductile behaviour detailing, can be found in seismically active areas. The level of ductility exhibited by these bridges is unknown. A crucial seismic performance indicator for older bridges with piers containing round reinforcing bars, i.e. the bending moment-curvature curve (M- curve), is considered in this paper. The results of analytical, experimental and numerical approaches for determining the M- curve are compared, and conclusions on the effect of round reinforcement slippage are presented.

Objectives. The article reflects the results of the numerical analysis of the earthquake-resistant building on kinematic supports. To this end, the problem is reduced to solving the nonlinear stochastic Cauchy problem. The solution is constructed by the method of successive approximations. The probabilistic characteristics of the oscillation of the building are determined without the use of linearization techniques. An algorithm for solving this problem, which allows to perform numerical experiments on a computer to study the operation of a earthquake-resistant building on kinematic sup-ports, is given.Method. The acceleration of the earth's surface during an earthquake is represented as a non-stationary random Gaussian process. This approach is now generally accepted and beyond doubt. The study of vibrations of the building on kinematic supports under the influence of strong earthquakes is reduced to the solution of the stochastic nonlinear Cauchy equation. This equation is solved by iteration. The acceleration of the earth's surface is a function of three random variables. The required probability is represented as a triple integral, which is calculated using a computer.Result. The basic information about the considered kinematic supports is given. The Cauchy problem is formulated for the case of oscillations of a earthquake-resistant building on kinematic supports under the influence of strong earthquakes. The algorithm allowing to solve this equation is described in detail. The probability of finding the movements of the building within certain limits is represented as a triple integral. The results of numerical experiments carried out on a computer are given. The corresponding graphs are constructed using real accelerograms of strong earthquakes that occurred in the cities of Taft (USA) and Gazli (Uzbekistan).Conclusion. This article describes the method of calculation of earthquake-resistant buildings on kinematic supports, using the data of real strong earthquakes. Based on the results of numerical experiments conducted on a computer, graphs of the reliability of seismic stability of the building in earthquakes. The constructed algorithm and the developed technique can be used in the calculation and design of earthquake-resistant buildings both on conventional supports and on kinematic supports.

In this paper, a seismic-resistant method for reinforced concrete structures in agricultural water engineering is proposed by analyzing reinforced concrete structures. The dynamic response of the simplified high concrete gravity dam model under earthquake, the damage mechanism, and the comparison of the seismic effect based on the two reinforced concrete finite element models under various reinforcement schemes are studied and discussed, the seismic weak parts of the dam are clarified, and the preferential conditions and reasonable reinforcement schemes for the reinforcement of the two reinforced concrete finite element models are proposed, which provide a reference for the design of seismic reinforcement of 200 m class high dams. This paper presents the optimal conditions and reasonable reinforcement solutions for the seismic reinforcement design of a 200-meter-high dam. In this paper, the three-dimensional consistent viscoelastic artificial boundary is applied to the structural foundation interaction problem as a local artificial boundary. Three seismic time-dependent acceleration curves are generated according to the seismic design code spectrum of hydraulic buildings, and then the seismic time-dependent acceleration curves are converted into equivalent loads applied to the three-dimensional consistent viscoelastic artificial boundary to analyze the response characteristics of the picket structure under seismic action. The interaction between reinforcement and concrete is considered, and the tensile stiffening effect of reinforced concrete is simulated by modifying the softening section curve of the concrete. Based on the separated reinforced concrete model, the seismic analysis of the picket structure with different reinforcement ratios is carried out. The effects of reinforcement rate on stress, displacement, damage extension, energy dissipation, and other indicators are investigated. The results show that the reinforcement measures help to slow down the damage development and improve the stress state, but have little effect on the displacement and acceleration. According to the analysis results, the design of the frame structure opening and closing machine beam was improved, the beam system arrangement was optimized, and the dynamic response analysis of the structure under rare earthquakes was carried out again. The analysis results showed that the problem of excessive vertical deformation of the girder where the opening/closing machine is located under rare earthquakes was solved by improving the girder arrangement of the opening/closing beam system. [ABSTRACT FROM AUTHOR]

Earthquakes can cause serious damage to traffic infrastructure and even induce the collapse of bridges, which is even worse. At the same time, earthquakes are key factors to the overall service capacity of the traffic network. Therefore, mastering the failure mechanism and evaluating accurate residual seismic resistance of a bridge under earthquakes are of great significance to the rapid recovery of traffic network function. For this reason, a performance-based methodology for the evaluation of the residual seismic resistance of a suspension bridge is proposed. In this paper, we provide the fragility curves of the key sections of the pier by incremental dynamic analysis (IDA), mathematical statistical analysis, and the damage law and obtained the failure state of the structure and the overall seismic capacity residual ratio and the stage seismic capacity residual ratio of the structure. Then, based on the research results of IDA, the reserve seismic capacity is analyzed as well. The research results explore a new method to accurately estimate the residual seismic capacity for resilience assessment.

Nowadays seismic resistant structural design is based on force analysis and on representing the earthquake effect as equivalent static forces set as elastic response spectra (response spectrum method). These response spectra link the law of earth motion to the absolute acceleration of the structure's model. This approach takes no account of either the effect of intense motion duration or of the plastic behavior of the structure. The frequency content and the duration of earth oscillations immediately influence the energy taken in by the building and causing damage to its elements. In theoretical terms, the input energy depends on the model of the structure in question. The input energy is determined by a dynamic calculation for the selected model or by theoretical assessment. Then, the energy is compared to the energy capacity, i.e. maximum energy which can be conveyed to the building before it collapses. Conventionally, the energy capacity is compared to the plastic component of the input energy (absorbed by the building). This forms the basis for the energy method of seismic structural design. The present paper considers a seismic resistance feasibility calculation technique employing non-linear statistical analysis based on the energy-centered approach. Non-linear static and non-linear dynamic calculations were run for a three-story frame. The two methods were benchmarked against each other, the importance of the higher modes of vibration was exposed, the importance of analyzing their influence on the system's response was emphasized

The beneficial effects of buckling-restrained braces (BRBs) in bridge engineering have attracted widespread attention in recent years. Firstly, this paper introduces the basic working mechanism of traditional BRBs, and the new forms and new materials of BRBs are also being studied. Secondly, the responses and performances of BRBs applied to (piers) girder bridges, cable-stayed bridges, and arch bridges are systematically studied. Besides, studies on the connection nodes between BRBs and structures have been paid more and more attention. By comparing and analyzing the damping effect of BRBs alone and that of BRBs with other seismic isolation devices on a bridge, it is determined that a reasonable BRB layout can effectively improve the seismic performance of the bridge with better energy dissipation capacity and load-carrying capacity than other components, but they are less used in practice and do not have mature specifications to be applied on different bridges. Finally, the following trends in BRB development in bridge research are discussed: the diversity of BRB forms, applications of BRB, node connection security, and combined damping measures. These areas should be explored through in-depth theoretical and experimental research.

The low masonry structure is the most commonly applied building type in rural China. It is possible to install small-diameter, low cost, and easily constructed laminated rubber bearing (LRB) components. Isolation technology has broad application prospects in rural buildings. We developed a small-diameter LRB in this study wherein the isolation layer is set above the floor for easy installation and replacement. We built and tested 4 walls to observe the effects of different LRB thicknesses; we assessed test respective phenomena and seismic parameters accordingly. We ran another test on five small-diameter LRB components with varying horizontal stiffness, different forms of shear strain-equivalent horizontal stiffness, and postyield stiffness while changing the fitting formula for the second shape coefficient to give small-diameter LRB design providing gist.