Search

Dynamic response of a shallow circular inclusion under incident SH wave in radially inhomogeneous half-space is researched by applying complex function theory and multipolar coordinate system. Considering that the mass density of the half-space varies along with the radius direction, the governing equation is expressed as a Helmholtz equation with a variable coefficient. Based on the conformal mapping method, the Helmholtz equation with a variable coefficient is transformed into its normalized form. Then, the expressions of incident wave, reflected wave and scattering wave are obtained, and the standing wave function is deduced by considering the circular inclusion subsequently. According to displacement and stress continuous condition of the inclusion, the undetermined coefficients in scattering wave and standing wave are solved. Finally, dynamic stress concentration factor around the inclusion is calculated and discussed. Numerical results demonstrate the validity of the method and influential factors of dynamic stress concentration factor.

Based on complex function methods and a multipolar coordinate system, the scattering induced by a cylindrical cavity in a radially inhomogeneous half-space is investigated. Mass density of the half-space varies depending on the distance from the centre of the cavity while the shear modulus is always constant. The wave velocity is expressed as a function of radius vector and the Helmholtz equation is a partial differential equation with a variable coefficient. By means of a conformal mapping technique, the Helmholtz equation with a variable coefficient is transferred into its normal form. Then, displacement fields and corresponding stress components are deduced. Applying the boundary conditions, dynamic stress concentration factors around the cavity are obtained and analyzed. Typical numerical results are presented to demonstrate the distribution of dynamic stress concentration factors when influencing parameters are assumed.

Based on the complex function method and a multipolar coordinate system, scattering of shear waves by a cylindrical inclusion in an anisotropic (orthotropic) half space is studied. In order to find the solution of shear waves, the governing equation is transferred into its normalized form. Then, the scattering wave in the half space and the standing wave in the inclusion are deduced. Different incident wave angles and anisotropies are considered to obtain the reflected wave. Then, the unknown coefficients in scattering wave and standing wave are found by utilizing the continuous condition at the boundary of the inclusion. Subsequently, the dynamic stress concentration factor (DSCF) around the inclusion is calculated and analyzed. The results demonstrate that the distribution of the DSCF is influenced by the anisotropy of the half space, and the value of the DSCF is mainly affected by the wave numbers ratio and the shear modulus ratio.

By applying the theory of complex function and the image principle, this paper investigate the dynamic stress of wave propagation problems in an exponentially inhomogeneous right-angle plane with a circular cavity. The density is assumed to be an exponential change along x -axis, and the shear modulus is constant. Due to the inhomogeneity, the coefficient of the Helmholtz equation is a variable. Based on the theory of complex function, Helmholtz equation is transformed with a general conformal transformation method. By using the image principle, the right-angle plane is first mirrored as the half-space in order to find the expressions of the incident wave and the reflected wave. Then, the half-space is mapped into the finite one for solving the scattering problem of the wave. In order to verify the validity of this method, wave equation in inhomogeneous media is degenerated to the equation with constant coefficients. By truncating a set of infinite algebraic equations, the coefficient of the series is determined. The expression of scattering wave is given by the traction-free boundary condition. The displacements and stress fields are proposed. Dynamic stress concentration factor (DSCF) around circular cavity is calculated in exponentially inhomogeneous media.

With regard to the characterization of structural vulnerability, a new definition of seismic vulnerability index and the corresponding formula are given. The new formula is merely associated with the vulnerability matrix, which shows that the contribution of different damage grade to the vulnerability index is different. Finally, based on earthquake damage matrix, the vulnerability index of three rural structures including brick-wood structure, civil structure and masonry concrete structure is presented. The seismic capacity of rural dwellings can be analyzed by vulnerability index.

Earthquake field work is complex and urgent, and efficient and orderly emergency work plays an important role in reducing casualties and economic losses. Scientific and reasonable working mode and intelligent information technology means are the key to ensure the efficient and orderly development of seismic field work. At present, domestic and foreign standards and systems for seismic field work have been developed and established, and disaster investigations and assessment software based on mobile terminals have been developed. On the basis of explaining the importance of earthquake field emergency work, this paper summarizes and compares the domestic and foreign earthquake field work modes and disaster investigation information service software, introduces the application of various software and its shortcomings, and discusses the development direction of disaster investigation information system in earthquake field work.

Applying the finite difference method and finite element method (FDM-FEM), a methodology for handling propagating of the elastic wave is proposed. The coupling of two methods is based on the construction of a transitional zone which can pass data, assign values and eliminate the boundary effect. The practical benefits of FDM-FEM are illustrated in the simulation of wave propagating in the crack structure. Different computational domains use different methods. Hence, the simulation of wave propagation is more effective and simplifies code development and subroutines. Then, the characteristics of wave propagation are reflected through the text.

Surface motion of anisotropic half space under plane SH wave is investigated by means of complex function method and multi polar coordinate system. The anisotropy of the half space is considered in order to satisfy practical condition. Three defects (cavity, inclusion and lining) are discussed to demonstrate different influences on surface motion. Based on different boundary conditions of defects, surface displacement amplitudes of the half space under plane SH wave are investigated. Numerical results show that surface motion of the half space is affected by the defect embedded significantly, especially when the half space is anisotropic.

In the current code of seismic design in our country,infilled wall are considered as non-structural component and do not participate in the seismic checking. In the bottom frame structure, the infilled wall of the first floor often change the number and position for using function at random,this will have unfavorable impact on the main structure. In this paper, a serious damaged bottom frame structure in high intensity area in Wenchuan earthquake is taken as the research object,and 3 comparative calculation models are designed, elasto-plastic time-history analysis is carried out on the use of ABAQUS finite element software. The calculation results show that: the first layer containing infilled with high wall content ratio will reduce the first floor damage, but causing the weak layer of the overall structure transfer from the bottom to transitional masonry story which aggravates damage, at the same time, an appropriate increase in wall content ratio can reduce the torsional response at a certain extent; nonuniform arrangement infilled wall has little effect on the floor deformation and resistance, but it will increase the torsional response of the whole structure.

For the study of irregular plane adverse impacts on the bottom frame structure seismic performance, in this paper, a serious damaged bottom frame structure in Wenchuan earthquake is taken as the research object,and a comparative calculation model is designed and elasto-plastic time-history analysis is carried out on the use of ABAQUS finite element software. The calculation results show that: the stiffness center of floor with irregular plane does not coincide with the center of mass, this eccentricity will produce torsional response under horizontal earthquake action. Bottom frame shear layer has strong stiffness at the center, around the lack of lateral load resisting member will cause interlayer torsional rigidity insufficient, further increasing the torsional response of structures, aggravated the damage. The lateral stiffness ratio under the same conditions,the design method of the contrast model is more reasonable, and has lighter damage under the the same intensity grade, improve the seismic capability of the structure, and provides the ideas of design method of this kind of structure.

The natural frequency of model was analyzed by finite element software in the first and the result was consistent with the experience formula. Then, time history of ground motion was inputted. The seismic capacity of the structure was analyzed by parameters as structural damage, seismic shear and acceleration. Structural damage in seismic “three levels” and the results of seismic appraisal were consistent. The injury site structure put forward strengthening measure of circle beam and structural column. Scientific basis and technical support for seismic strengthening were provided for Tianjin Western-style dwellings.

In Northeast China, brick-wood building is widely distributed, but due to the absence of the seismic code, there are many differences between structure and construction technology in different regions .That makes the seismic capacity is uneven. Therefore, we chose the typical brick-wood building in the Northeast as the object of study. Based on seismic data in QianGuo earthquake, using numerical simulation technique to analyze the earthquake damage and failure mechanism of brick-wood building, explores the causes of seismic damage. On this basis, we proposed the new seismic reinforcement technology measures, by comparison has gone through a transformation of a typical brick-wood building aseismic capacity significantly better than the prototype. Meanwhile, this research helps to understand the seismic performance of brick-wood buildings in the Northeast, and to develop appropriate policies on disaster for the region is of great significance.

Single-story brick column workshops are widely used as the production or storage room of medium and small-sized enterprises in China. Based on the field investigation of single-story brick column workshops at the earthquake-affected area after Lushan 7.0 earthquake, the damage characteristics of workshops are summed up. Damage prediction analyses are carried out for two typical single-story brick column workshops, and failure mechanism researches are conducted by using ABAQUS finite element software for a workshop. Finally, according to the results of failure mechanism researches, some relevant suggestions of the seismic reinforcement are put forward.

Due to the development of the computer hardware and the difficulties in determining the constitutive relation, it is difficult to research the crack propagation of large-scale masonry with the finite elements analysis method. The paper analyses the single storey concrete block masonry experimental model with the software LS-DYNA, using winfrith concrete material model instead of masonry material. And the calculated results were compared with the test results. The comparison indicates that the crack propagation of masonry can be simulated better with winfrith material model, which can be used in the finite elements analysis of large-scale masonry.

The Wenchuan earthquake occurred on May 12, 2008 (Beijing Time) caused great casualty and economic losses, a large number of masonry buildings were damaged in various degrees in this earthquake. The masonry residential buildings are widely used in China, and the study on them is significant. Although the masonry residential building discussed in this paper which was located in the highly intensity region was damaged severely, it hasnt collapsed and has very typical earthquake damage. The story comprehensive seismic capacity indexes are developed to anti-collapse capacity index which are used to calculate anti-collapse capacity of the building, and the results are also used for comparative analysis with the results calculated by means of structure vulnerability analysis. The earthquake resistant capacity of masonry residential buildings are discussed and analyzed. Finally, some reasonable suggestions on the seismic strengthening and reconstruction of this kind of building after disaster have been given.

The brick-timber structures have a long history and are still used widely in Chinese rural area at present. A large amount of structures were damaged in Wenchuan earthquake occurred on May 12, 2008, and the brick-timber structures in different intensity regions were investigated in detail. Based on the investigate data of Wenchuan earthquake and other previous seismic data, the typical damage of brick-timber structures are summarized and the earthquake resistant design methods and research status are discussed, the earthquake resistant capability of brick-timber structure are also analyzed. Combined with current country codes, the constructional measures for earthquake resistance and construction technology of brick-timber structures are studied. Finally, some reasonable suggestions on the seismic strengthening and reconstruction of this kind of structure after disaster have been given.

Damage data of 52 masonry structures in Yuxi Village which is the macroscopic epicenter of Ms 7.0 LuShan strong earthquake were summarized and analyzed to study basic seismic capacity of the rural residence in Southwest China, and the following conclusions were obtained: summarized structural features of the main rural residence structure in Southwest China that exemplified by Yuxi Village; summarized damage characteristics of masonry structure in Yuxi Village, given brief analysis of its damage causes and provided reinforcement and improvement suggestions according to the corresponding damage characteristics; analyzed general damage characteristics of the village houses in the macroscopic level based on statistically analyze seismic site survey data. The basic seismic capacity of rural residential status in Southwest China is initially grasped, and it has important reference value to understand of the damage characteristics of various types of structure, the development of earthquake disaster mitigation planning and revision of seismic design code.

The increasing of equivalent floor live-loads is used to describe the weakening of ultimate carrying capacity of the structure by analyzing variety of the beam’s ultimate moment and ultimate shearing force and the carrying capacity and stability of the column of steel-frame in fire, the formulas of the beam’s ultimate shearing capacity, the carrying capacity and stability of column and the equivalent floor live-loads have been derived based on these. The variety rules of the carrying capacity of beam and column of the steel-frame with different thickness of the protection layers and the equivalent floor live-load have been analyzed in the example, the results showed that different equivalent floor live-load may be used to analyze the infection of fire temperature to the carrying capacity of structure in the computations of steel-frame in fire according to different time and fire temperatures of structure members, the mechanics computations of structure would be predigested and the variety of ultimate carrying capacity of steel-frame also could be estimated.

For nonlinear vibration problems, IHB method is an effective definite quantitative method. The theoretical foundation of IHB method is amplitude incremental variational principle. In this paper, amplitude incremental generalized potential energy principle and generalized quasi-potential energy principle with two variables are established, thus improving theoretical foundation of IHB method.

In this paper, it is a brief summary for the field survey on the 27 February, 2010 Malue mega-earthquake, Chile by a Chinese scientist team. This mission is to investigate the reason why such a great earthquake caused less causalities, less loss compared with Chinese Wenchuan and Yushu earthquake. This survey was sponsored by China Earthquake Administration and this paper focused on the strong motion data analysis, some building damage observation and tsunami. We gave a preliminary analysis for the strong motions characteristic and some typical building damage. The understanding of this great earthquake could be improved our knowledge for advancing societal resilience.

Based on the technology such as remote sensing(RS), geographic information system(GIS), 3D simulation, and damage prediction, the simulation technology of earthquake disaster scene (STEDS) is the important content of digital disaster reduction and has important research value, which can be used to decision support, virtual training, and popular science education and so on. The general idea of STEDS is introduced in this paper and the key technologies to simulate an earthquake disaster scene livingly are analyzed. Taking a real city for example, the disaster scene of building blocks is completed, which take different colors as the signs of different damage levels under earthquake effect. The 3D building model bases are established by 3D modeling technology, which include 3D intact building models and the damage ones with different damage levels. Based on the replacement rules of models, the preliminary disaster scene of 3D damage building models is realized.

In this paper, the dynamic responses of an arch dam in the case of normal water level and operating low water level were simulated by using additional mass model and incompressible finite element model for reservoir respectively. The results showed that the reservoir models have a great impact on dynamic response of arch dams. The maximum principle tensile stress using incompressible finite element model of fluid is less than that using additional mass model. With the depth of the reservoir water increasing, the hydrodynamic pressure acting ton the dam surface caused by earthquake force increased and the dynamic responses of dam also increased.

Based on the characteristic of cooler frame, the finite element model of air cooler frame is established using ANSYS software. Equivalent static load method and response spectrum method were used for the seismic performance analysis of cooler frame. The equivalent static load is applied at the center of gravity of various masses using MPC184 rigid beam for transferring the load. The deformation and stress of cooler using equivalent static load method are larger than that of cooler using spectrum response method. For this reason, it can be said that the equivalent static load method is more conservative. At last the deformations and stresses of cooler frame using two methods are checked by ASME AG-1 specification. The results showed that the deformation and stress of cooler frame meet the requirements.

This paper addresses the stability behaviour in-plane and the critical load of the double-hinged circular steel arch when subjected to elevated temperature caused by fire, the study is restricted to the thermoelastic structural response of the steel material and therefore the high-temperature effects of yielding are not considered. In order to model structural response of the steel arch under thermal loading, some significant factors such as the degradation of the stiffness of the steel arch prior to yielding at elevated temperatures is taken into account, the formulation of critical load is proposed and their variation trends with temperatures is analysed. The proposed method has significant potential for use in the analysis of steel arches subjected to uniformly distributed load at elevated temperature and can provide a foundation for codified procedures in design.

All actual vibration systems are nonlinear in character. For nonlinear vibration problems, IHB method is an effective definite quantitative method. The theoretical foundation of IHB method is amplitude incremental variational principle. In this paper, amplitude incremental complementary energy principle for nonlinear vibration is established.

The multistory masonry buildings with variable wall thickness along the height have suffered different degrees of damage subjected to the Wenchuan earthquake. In order to study the failure mechanism of such masonry structure under the earthquake, three types of five-story structure of computational model are firstly introduced in this paper, including (1) the wall thickness of five stories is 240mm; (2) the wall thickness of the first floor is 370mm, and that of the upper four stories is 240mm; (3) the wall thickness of the first and second story is 370mm, and that of the other stories is 240mm. Then, the elastoplastic time-history dynamic analysis is carried on with the story shear model by the finite element method, and the ground motion of El Centro waves are adopted as earthquake input motion. The analysis results show that variation of wall thickness along height can easily cause stiffness mutation of the upper and lower floor, lead to local floor deformation concentration and soft floors, and the change of failure mechanism of the structure. Finally, it is suggested that some appropriate seismic resistance measures should be taken to meet the lateral stiffness ratio of the upper and lower floor in the later design of this structure, or this kind of structure should be avoided using as far as possible.

In recent years, many earthquakes occurred in our country. Some is big, but most are small or middle earthquakes. Usually earthquake damage ratio of buildings in low intensity area can be attained from on site survey. But it is important that how to evaluate the seismic performance of existing building stock subjected to high intensity in earthquake-affected area. In this paper, the expectation and variance value of damage probability in known intensity is calculated by making the probability disperse. Supposing that the damage probability in each intensity obeys to Beta distribution. The expectation and variance value of damage probability in other intensity is given by comparing to that of criterion earthquake damage matrix. So the parameter of Beta-distribution function is calculated from the expectation and variance in other intensity. Then the probability of each damage grade in other intensity is gained. This approach makes the damage matrix which is suitable for this region complete and provides the reference for earthquake damage prediction and earthquake economic loss evaluation. The result showed that this approach is feasible.

In this paper, we study the problems of scattering of out-of-plane line source load by half-space shallow-embedded circular lining structure and a crack in the field of linearly elastic dynamic mechanics. This is an essential solution to the displacement field for the elastic space possessing shallow-embedded circular lining structure and a crack while bearing out-of-plane harmonic line source load at arbitrary point. The wave function of scattering of shallow-embedded circular lining structure impacted by incident steady SH-wave is constructed based on the symmetry of SH-wave scattering and the method of multi-polar coordinates system. Then a crack is made out using the method of “crack-division”. Thus expressions of displacement and stress are established when shallow-embedded circular lining structure and a crack are both in existent. Finally, with two different dimensionless parameters, numerical results of scattering of out-of-plane line source load by half-space shallow-embedded circular lining structure and a crack are obtained and numerical examples are provided to show the influence of wave number ratio, shear modulus ratio, thickness ratio and the ratio of distance between the center of the different cavity and ground surface and the radius of the circular lining structure upon the dynamic stress concentration factor(DSCF) and dynamic stress intensity factor(DSIF) at crack tip.

The Wenchuan earthquake occurred on May 12, 2008 (Beijing Time) caused great economical loss and large amount of buildings were destroyed. Many of single-story reinforced concrete industrial buildings in Hanwang town located in the highly seismic region were damaged, and the damaging phenomenons are very typical. According to the damage survey and analysis of typical seismic damage for the single-story reinforced concrete industrial buildings located in Hanwang town, the damage distribution and failure characters of these buildings are summarized in this paper. The single-story reinforced concrete industrial buildings which were designed according to current seismic design code have better earthquake resistant behavior than those old single-story reinforced concrete industrial buildings and the damaging phenomenon show some new features. Finally, combining current seismic design code of our country and the earthquake damage lessons, some reasonable suggestions on the work of seismic strengthening and earthquake resistant design of the single-story reinforced concrete industrial buildings have been given.

In this paper, the vulnerability of the multi-storey reinforced concrete is classified and analyzed according to three control factors: construction age, story and uses. And the different categories vulnerability matrices of multi-story reinforced concrete are obtained from the monomer sample buildings which are already evaluated. The proportion of construction area of different categories can be attained from buildings census statistics. Then the vulnerability matrix of concrete building group in study region can be established by sum-product of construction area ratio of each vulnerability class in study region and each class vulnerability matrix. Finally, the vulnerability matrix of reinforced concrete structure of Xi'an Yanliang District was obtained using this approach. After comparing with the traditional earthquake damage prediction method, it is shown that this method is feasible, simple idea and high reliable and can be used for rapid assessment of post earthquake.

In this paper, the typical seismic damage of earthquake fortification and non-earthquake fortification masonry buildings are analyzed and the causes are illustrated, which are based on a large number of earthquake disaster survey data of Ms8.0 Wenchuan earthquake, Ms6.4 Baotou earthquake and Ms7.8 Tangshan earthquake and so on. According to the damage statistics data of several past earthquakes of China in recent years, the difference of damaging phenomenon and rate of earthquake damage of earthquake fortification and non-earthquake fortification masonry buildings in highly and lowly seismic regions are discussed and analyzed. Finally, based on the analysis conclusions, how to improve the seismic capacity of masonry buildings are discussed combining current seismic design code of China and some reasonable suggestions on the post-disaster reconstruction of masonry buildings have been given.

On 12 May 2008, a magnitude 8.0 earthquake happened in Wenchuan, Sichuan province, China .It was the most serious earthquake in china since 1949, causing very huge casualties and engineering damages to the buildings. In the earthquake, a reinforced concrete frame structure of Beichuan Hotel in Beichuan County collapsed completely because of the unsuitable arrangement of column network, and the engineering damage was characteristic. In the paper, the properties of material nonlinearity were considered ,the nonlinear analysis model of reinforced concrete frame structure was established, the time history analysis and nonlinear static analysis were used during inelastic stage, the main cause of structural destruction was obtained, the influence of the arrangement of column network on the structure was discussed.Therefore ,the results can provide valuable reference for the seismic design of reinforced concrete frame structure.

During Wenchuan Ms 8.0 earthquake, masonry buildings have suffered severely damaged and collapsed, causing heavy casualties and huge economic losses. In this paper, based on seismic site survey data, some new phenomena and characteristics of earthquake damage in comparison with the 1976 Tangshan earthquake, such as seismic damage of large space buildings, inclined or “X” shaped crack in wall between windows or spandrel wall, stair damage, falling of precast reinforced concrete slab and horizontal crack at the bottom of structure, are discussed in detail. Then, the impact factors of seismic capacity of masonry building in Wenchuan earthquake, including construction age, seismic fortification, bay size, floor (roof) form, layer number, thickness of bearing wall are analyzed, respectively; Finally, some recommendations on seismic design and reconstruction of masonry structure by the seismic design code are proposed.

Based on the nearly 5,000 building samples investigated on site, damage characteristics of different types of building structures which located in different intensities regions are described and the reasons are analyzed in this paper. Three kinds of structural damage characteristics have been summarized as follows: 1) fortified masonry structures and unfortified ones; 2) masonry buildings with bottom frame; 3) reinforced concrete frame structures. The damage ratio of these three kinds of buildings in different intensities is obtained and the vulnerability has been compared. It provides the reference for those people who work for earthquake engineering to know the earthquake damage of different types of structures with fortified or unfortified. Also it provides important reference for revising seismic design code.

A great earthquake of magnitude 8.0 occurred on May 12, 2008 (Beijing Time) in Wenchuan, Sichuan Province of China. Leigu town, which adjoins Beichuan county, was the most seriously damaged place in this earthquake. The teaching buildings were destroyed severely and the earthquake disaster phenomena is very typical. In this paper, firstly, the characteristics of structures and the earthquake damage of the teaching buildings in Leigu town are introduced in detail. Secondly, their damage states are calculated by means of structure vulnerability analysis, which are used for comparative analysis with actual damage states, and the influencing factors on seismic behavior are analyzed. Finally, some reasonable suggestions on the reconstruction of teaching buildings after disaster have been given.

A great earthquake of magnitude 8.0 occurred on May 12, 2008 (Beijing Time) in Wenchuan, Sichuan Province of China, caused huge casualties and economic losses. As a member of field investigation team of China Earthquake Administration (CEA), the decoration and indoor/outdoor properties losses of the earthquake-stricken areas were investigated in detail, which include Dujiangyan, Mianyang, Deyang, Chengdu, Guangyuan city, and other areas. In this paper, based on statistical analysis of collected survey data, the investigation results and characteristics of buildings decoration and indoor/outdoor properties losses of the earthquake-stricken areas are given firstly. Then, the relationship between decoration damage grade and main body structure damage grade is analyzed, and loss ratio of building decoration damage in urban zones is also provided on the basis of expert questionnaires. Thus, some foundations are established for loss assessment method of building decoration damage in urban zones.

The national standard《Post-earthquake field works Part 4: Assessment of direct loss》 (GB 18208.4-2005) has been playing an important role in earthquake loss assessment, relief organization and homeland rehabilitation since it was issued in 2005 in China. The earthquake losses assessed are much less than other natural disasters (such as floods, drought) or foreign earthquake losses. How to assess seismic economic loss reasonably has been a key issue domestic seismic workers concern. In this paper, an earthquake-induced building decoration loss assessment method for urban zones is presented firstly. Then, based on statistical analysis of collected more than 600 pieces of cost data and 30 pieces of expert questionnaires, the distribution proportion of moderate–and–high–grade decoration building, the proportion of decoration cost and total structure cost, the loss ratio of decoration damage in small, Medium and big cities are given, respectively. The correction coefficients are also given depending on different economic development and use. Finally, its practical application in Sichuan Wenchuan Ms8.0 great earthquake loss assessment is introduced. Thus, some references and basis for further modifying and perfecting earthquake loss assessment standard in China are provided.

The dynamic response of a circular lining structure and multiple cracks in an elastic half space while bearing impact loading is studied in this paper. This problem can be seen as the problem of defending of blast. The methods of Green's function, complex function and multi-polar coordinates are used here. First, the scattering wave which satisfies the condition of stress free on the ground surface of half-space containing a shallow-embedded circular lining structure impacted by incident SH-wave is constructed based on the symmetry of SH-wave scattering and the method of multi-polar coordinates system. Then a crack or multiple cracks in any position and direction can be constructed by Green's function and means of crack-division in half space. Finally the displacement field and stress field are established in the case of coexistence of circular lining structure and cracks, and the expression of dynamic stress intensity factor (DSIF) at the tip of crack is given. The interaction of inclusion and two cracks is chosen as numerical examples finally. According to nu-merical examples, the influences of different parameters on DSIF are discussed.

Scattering of SH wave by an elastic half space with a lining structure and a crack in any position and direction is studied with Green’s function, complex function and multi-polar coordinate method. First, a suitable Green’s function is constructed, which is a fundamental solution to the displacement field for the elastic space possessing circular lining structure while bearing out-of-plane harmonic line source load at arbitrary point. Then a crack in any position and direction is constructed by means of crack-division in half space. Finally the displacement field and stress field are established in the case of coexistence of circular lining structure and crack, and the expression of dynamic stress intensity factor (DSIF) at the tip of crack is given. According to numerical examples, the influences of different parameters on DSIF are discussed.

Based on Green’s function, complex function and multi-polar coordinate system, the far field solution of SH wave scattered by an elastic half space with a circular cavity and a crack at an arbitrary position and orientation is investigated. First, a suitable Green’s function is constructed, which is the fundamental solution of the displacement field for a half space with a circular cavity subjected to an out-plane time-harmonic line force at an arbitrary position in half space. Second, by means of crack-division technique, a crack with any location and orientation can be constructed in the region of the half space. The displacement field and stress field are established in the situation of coexistence of circular cavity and crack. At last expressions of far field, such as displacement mode of scattering wave are deduced. Some examples and numerical results are illustrated. The influences of the combination of different media parameters on solutions of far field are discussed.

Steel and concrete were the most important building materials, reinforced concrete was widely used in building structures. For the study of the influence of steel bar content in reinforced concrete columns, three specimens were designed for pseudo static test. The test shows that: the stirrup ratio does not significantly affect the bearing capacity and stiffness degradation of column, but when the stirrup ratio is too low will reduce the ductility and energy dissipation capacity of column. To improve the ratio of longitudinal reinforcement can significantly improve the bearing capacity of the column, but will decrease the energy dissipation and ductility, stiffness degradation becomes more serious. Introduction In building structure, reinforced concrete structure was a form of the most widely used, steel and concrete could work together was determined by the material properties of its own. First of all, steel and concrete had approximately the same linear expansion coefficient, and will not produce excessive stress due to different environment. Secondly, there was good adhesion between steel and concrete, reinforced rib could improve the mechanical engagement between concrete and steel. The stirrup was used to meet the shear strength of the inclined section, and connected reinforcement and compressive region concrete. Therefore, reinforcement ratio had an important effect on mechanical properties of the mechanical behavior of reinforced concrete column. Specimen Design and Test Methods Specimen Design. Three reinforced concrete frame column specimens were designed. The stirrup ratio was different between Z1 and Z2, while the stirrup ratio was different between Z1 and Z3.The specific parameters were shown in tab.1. Tab.1 The design parameters of reinforced concrete frame column No. axial compression ratio stirrup ratio the ratio of longitudinal reinforcement shear span ratio Z1 0.9 Ф 8@85/150 (4) (1.8%) 12Ф 14 (2.05%) 2.92 Z2 0.9 Ф 6@150 (2) (0.29%) 12Ф 14 (2.05%) 2.92 Z3 0.9 Ф 8@85/150 (4) (1.8%) 12Ф 20 (4.19%) 2.92 Material Characteristic Test and Results. Steel tensile strength was tested by five 6, two 8, four 14, two 22, the average results were shown in Tab.2. The grade of concrete strength was C30, three concrete test cube by 150mm×150mm×150mm in one-time-concreting were taken through axial compressive strength test, the results were shown in Tab.3. International Conference on Material Science and Application (ICMSA 2015) © 2015. The authors Published by Atlantis Press 571 Pseudo-static Test. The test method was the quasi-static test [1] , by applying multiple reciprocating cyclic loading on the component, the structure repeated the process of loading and unloading in the pros and cons direction, to simulate the deformation characteristics and force characteristics of the structure in reciprocating vibration during earthquake. The purpose was to establish the restoring force characteristics of structure under earthquake, and determine the calculation model of restoring force of structural members, which could judge the seismic performance of structure in the strength, deformation and energy dissipation. Tab.2 Material characteristic results of steel bar Steel bar Diamete r[mm] Yield strength[MPa] Ultimate strength [MPa] Yield strain Stirrup (HPB235) 6 447 638 0.002235 Stirrup (HPB235) 8 417.5 527.5 0.002088 Longitudinal reinforcement (HRB335) 14 493.8 657.8 0.002469 Longitudinal reinforcement (HRB335) 20 480 597.5 0.0024 Tab.3 Material characteristic results of concrete test cube No. Axial compressive strength [MPa] 1 47.93 2 46.01 3 45.73 Average 46.5 Loading Equipment. The reinforced concrete column end was anchored and horizontal cyclic loading was applied on the top. A vertical concentrated load was applicated on the top of the column, though and upper roller device between the hoisting jack and reaction beam to ensure the top of the column could produce free horizontal displacement[2]. The test equipment was shown in Fig.1. The horizontal load is loaded by the method of deformation control: When the specimen cracked, according to multiple cracking displacement to load step by step, two cycles per level, until the first cycle load of the structure was lower than 85% maximum load , and it was considered that structure had already destroyed. The test loading program was shown in Fig. 2. Fig.1 Test equipment Fig.2 Test loading program Experimental Phenomena. Specimen Z1 was taken as an example to explain the phenomenon in the process of test. When 2Δ, mortar and concrete were peeled on the upper column at the height of 1-1.5 section, vertical cracks appeared, the compression zone of mortar layer appeared obvious signs of crushing. When 5Δ, the crushing of concrete significantly increased, cracking phenomenon

We present the Green's function for the scattering of SH waves by an elliptical cavity in an elastic half-space combining with the technique of conformal mapping and multi-polar coordinate system. Then we deduce the dynamic stress concentration factor (DSCF) around the oval cavity based on the Green's function. Numerical results are carried out by changing the position and the shape of the cavity, the wave number and the coordinate of the wave source, which show that the DSCF is affected heavily by those parameters, especially when the cavity is near the surface of the half-space or the source of SH waves.

The problems of SH-wave scattering, which is caused by half-space circular cavity near the bimaterial interface and crack of arbitrary length and arbitrary position, are studied in this paper based on the field of elastodynamics, and the methods of Green's Function, complex variables function, the method of crack-division and multi-polar coordinates are used here. Firstly, a suitable Green's function is constructed, which is the key technology of this problem. Two Green's functions are needed here: The first one is an essential solution of the displacement field for the elastic half-space containing a circular cavity and crack with arbitrary length and arbitrary position under the out-of-plane harmonic line-loads at an arbitrary point; The second Green' function is an essential solution of the displacement field for the elastic half space subjected to the out-of-plane harmonic line source loads at half space surface arbitrary point. The scattering of SH-wave by the crack at an arbitrary position and a circular cavity near the bimaterial interface is investigated, the problem can be regarded as harmony model: the bimaterial media is divided into two parts along the horizontal interface, one is an elastic half space with a circular cavity and a crack, and the other is a complete elastic half space. The horizontal surfaces of the two parts are loaded with unknown anti-plane forces in order to satisfy at the linking section. A series of Fredholm integral equations can be set up through continuity conditions. Then, the solution of the problem can be reduced to a series of algebraic equations and solved numerically by truncating the finite terms of the infinite integral equations, the analytical solution of displacement field and stress field of scattering of SH-wave by the crack and circular cavity near the bimaterial interface are given. Numerical examples are provided to show the influences of wave numbers, incident angle, the distance between the center of the circular cavity and horizontal surfaces, the distance between the center of the circular cavity and crack, the angle of crack, the length of crack, and parameter combinations of different media upon dynamic stress concentration factor (DSCF).