Seismic Capability Research Articles

Seismic Proofing Capability of the Accumulated Semiactive Hydraulic Damper as an Active Interaction Control Device with Predictive Control

The intensity of natural disasters has increased recently, causing buildings’ damages which need to be reinforced to prevent their destruction. To improve the seismic proofing capability of Accumulated Semiactive Hydraulic Damper, it is converted to an Active Interaction Control device and synchronous control and predictive control methods are proposed. The full-scale shaking table test is used to test and verify the seismic proofing capability of the proposed AIC with these control methods. This study examines the shock absorption of test structure under excitation by external forces, influences of prediction time, stiffness of the auxiliary structure, synchronous switching, and asynchronous switching on the control effects, and the influence of control locations of test structure on the control effects of the proposed AIC. Test results show that, for the proposed AIC with synchronous control and predictive control of 0.10~0.13 seconds, the displacement reduction ratios are greater than 71%, the average acceleration reduction ratios are, respectively, 36.2% and 36.9%, at the 1st and 2nd floors, and the average base shear reduction ratio is 29.6%. The proposed AIC with suitable stiffeners for the auxiliary structure at each floor with synchronous control and predictive control provide high reliability and practicability for seismic proofing of buildings.

Seismic response of concrete gravity dam reinforced with FRP sheets on dam surface

This paper aims at exploring the effects of anti-seismic reinforcement with the fiber-reinforced polymer (FRP) material bonded to the dam surface in dam engineering. Time-history analysis was performed to simulate the seismic failure process of a gravity dam that was assumed to be reinforced at the locations of slope discontinuity at the downstream surface, part of the upstream face, and the dam heel. A damage model considering the influence of concrete heterogeneity was used to model the nonlinearity of concrete. A bond-slip model was applied to the interface between FRP and concrete, and the reinforcement mechanism was analyzed through the bond stress and the stress in FRP. The results of the crack pattern, displacement, and acceleration of the reinforced dam were compared with those of the original one. It is shown that FRP, as a reinforcement material, postpones the occurrence of cracks and slows the crack propagation, and that cracks emanating from the upstream surface and downstream surface are not connected, meaning that the reinforced dam can retain water-impounding function when subjected to the earthquake. Anti-seismic reinforcement with FRP is therefore beneficial to improving the seismic resistant capability of concrete dams.

Existing Frame Structure Seismic Capability Based on the Theory of the Reliability Analysis Method for Basic Research

The application in analytic hierarchy process and a second order moment method based on the practical simplified methods to analyze the reliability of existing structures, the reliability of each component in the floor according to the weight function is combined into the reliability of floor, floor of the minimum reliability as system reliability; Frame structure under the action of earthquake occurred shear failure as the main failure mode of structure, the shear capacity of column minus its share of the earthquake action is defined as the seismic reliability analysis of functions; Choose an engineering example illustrates the existing practical method for the seismic reliability analysis of frame structure.

Seismic Vulnerability Analysis of FRP Retrofitting Industrial Buildings

This study focus on derivation of such vulnerability curves using Fiber Reinforced Polymers technologies retrofitted conventional RC industrial frames with masonry infill wall. A set of stochastic earthquake waves which compatible with the response spectrum of China seismic code are created. Dynamic time history analysis is used to compute the random sample of structures. Stochastic damage scatter diagrams based different seismic intensity index are obtained. Seismic vulnerability of FRP-reinforced RC industrial frames is lower than unreinforced frames obviously, and seismic capability of frames using FRP technologies is enhanced especially under major earthquake.

Earthquake Damage Forms of Multi-Story Brick Masonry Structure and their Mechanical Analysis

In order to know seismic damage characteristics of multi-story brick masonry structure and improve its seismic capability, five kinds of earthquake damage or collapse forms of multi-story masonry brick structure are summed up based on earthquake disaster survey, each of which is analyzed with mechanics. And the failure mechanism of each seismic damage form of multi-story brick masonry structure are proposed, which provides effective engineering experience for the seismic or anti-collapse design of multi-story masonry brick structure. The research has the important significance in improving the seismic capacity of multi-story brick masonry structure and reducing the earthquake casualties.

Torsional Design Method of Bottom Frame Structure with Irregular Plane

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.

Investigation of Concrete-Filled Double-Skin Steel Tubular Columns with Ultrahigh-Strength Steel

Concrete-filled steel tubular (CFT) columns have been used increasingly in building structures because of their construction efficiency and provision of high stiffness and strength. A relatively new configuration design with inserted inner steel tubes, so-called concrete-filled double-skin steel tubes (CFDSTs), has been developed in the field. To promote the seismic capability of the CFT/CFDST columns further, the authors present results from an experimental investigation of CFT and CFDST columns using ultrahigh-strength steel. Eight scaled column specimens were examined by subjecting them to combined axial and flexural cyclic loadings. The performance of the CFT and CFDST design configurations using high-strength steel was comparable and both provide large moment capacities and elastic deformation capacities. The ultimate member moment capacity could be predicted accurately using a proposed simple formulation based on the concept of the superposed strength method. Various performance parameters are evaluated and discussed, and the influence of compressive strength of the concrete core, applied axial loads, and inserted inner steel tubes on the seismic behavior of the column members is clarified by the experimental results.

OGS improvements in 2012 in running the North-eastern Italy Seismic Network: the Ferrara VBB borehole seismic station

Abstract. The Centro di Ricerche Sismologiche (CRS, Seismological Research Centre) of the Istituto Nazionale di Oceanografia e di Geofisica Sperimentale (OGS, Italian National Institute for Oceanography and Experimental Geophysics) in Udine (Italy) after the strong earthquake of magnitude M=6.4 occurred in 1976 in the Italian Friuli-Venezia Giulia region, started to operate the North-eastern Italy Seismic Network: it currently consists of 17 very sensitive broad band and 18 simpler short period seismic stations, all telemetered to and acquired in real time at the OGS-CRS data centre in Udine. Real time data exchange agreements in place with other Italian, Slovenian, Austrian and Swiss seismological institutes lead to a total number of about 100 seismic stations acquired in real time, which makes the OGS the reference institute for seismic monitoring of North-eastern Italy. The south-western edge of the OGS seismic network (Fig. 1) stands on the Po alluvial basin: earthquake localization and characterization in this area is affected by the presence of soft alluvial deposits. OGS ha already experience in running a local seismic network in high noise conditions making use of borehole installations in the case of the micro-seismicity monitoring of a local gas storage site for a private company. Following the ML = 5.9 earthquake that struck the Emilia region around Ferrara in Northern Italy on 20 May 2012 at 02:03:53 UTC, a cooperation of Istituto Nazionale di Geofisica e Vulcanologia, OGS, the Comune di Ferrara and the University of Ferrara lead to the reinstallation of a previously existing very broad band (VBB) borehole seismic station in Ferrara. The aim of the OGS intervention was on one hand to extend its real time seismic monitoring capabilities toward South-West, including Ferrara and its surroundings, and on the other hand to evaluate the seismic response at the site. We will describe improvements in running the North-eastern Italy Seismic Network, including details of the Ferrara VBB borehole station configuration and installation, with first results.

Studies on Seismic Measures to Improve Masonry Infilled Wall

brittle nature of masonry infilled wall and the wrong connection with the main structure , resulted in the destruction phenomenon in the earthquake . Based on the destruction phenomenon ,this paper analysis the Earthquake damage of masonry infilled wall , according to code for seismic design of buildings (GB50011—2001) and code for seismic design of masonry structures (GB50003—2011) , some seismic fortification measures were proposed in this paper aimming to improve seismic capability of infilled wall, thereby alleviate loss caused by earthquake.

Improvements on Structural Static Pushover Analysis Method in High-Rise Building Structure

In this paper, a new analysis model to assess the structure seismic capability is established, using improved capacity spectrum method. The model can solve the problem of many unknown and big computation workload in the process of conventional Pushover analysis. Conventional Pushover is very complex when use in the analysis of structure dynamic problem and nonlinear problem, the new model can solve these problem.

Estimating magnitudes of prehistoric earthquakes and seismic capability of fault from landslide data in Noor valley (central Alborz, Iran)

Detecting the paleoseismological specifications as well as seismic capability of faults has specific importance in estimating the earthquake hazard in any region. The geomorphic indices are used as indirect procedures in the mountainous area. They are appropriate and applicable methods in recognizing the specifications of active tectonics and evaluating fault seismicity in the mountainous areas. In this regard, giant landslides can be pointed out as proper indices. These landslides are usually related to tectonics and triggered by earthquakes in many cases. In this research, giant landslides existed in Noor valley (central Alborz) have been considered as geomorphological indices for recognizing the seismicity of the region and the seismic capability of its faults. There are four giant landslides in this region (Baladeh, Razan, Vakamar, and Iva) used for the mentioned purpose. No historical earthquake has been reported around Noor valley. However, the existence of giant and old landslides, related to earthquake, indicates the occurrence of numerous prehistoric earthquakes. In this research, three different age classes have been determined (Late Holocene, Early Holocene, and Late Pleistocene) for landslides. By the way, the possibility of identifying multiple earthquakes is provided in this area. The magnitudes of earthquakes are estimated as 7.7 ± 0.49 to 7.9 ± 0.49 based on their relations with maximum volume of displaced material. Regarding the distribution of landslides and other evidences, the eastern segment of Baladeh fault has probably been the main cause of the earthquakes.

Experimental and Numerical Study of Enhancing the Seismic Behavior of Rammed Earth Buildings

Rammed earth structures are widely used as farmers dwellings in the southwest of China, however, they are extremely vulnerable to earthquake loadings. An economic, environmental-friendly and less-intervention seismic retrofitting technique is required to reinforce these dwellings so as to increase regional seismic capability. A preliminary laboratory testing was conducted to investigate the enhancement of the seismic behavior of the rammed earth wall with externally bonded fibers. Different retrofitting materials and adhesives were tested to characterize their mechanical properties and bonding performance when externally glued on rammed earth blocks. The most suitable and practical retrofitting material and adhesive were chosen based on the experimental results. Furthermore, a numerical analysis was performed to investigate the improvement of the shear capacity of the rammed earth wall with the proposed technique. It was verified that the proposed retrofitting technique is a promising option for seismic retrofitting of rammed earth walls.

Comparison Analysis of Typical Buildings in North-South Seismic Belt

In North-south earthquake belt, half of more than Ms 8.0 great earthquakes were centralized since the history records were existed in our country. In order to study the typical buildings in this seismic belt, the seismic damages of the typical buildings occurred during 22 earthquakes in North-south earthquake belt, whose earthquake magnitude were more than Ms 6.0, were organized and analyzed. The seismic damage and its matrix of kinds of buildings belonging to the North-south earthquake belt in different intensities were obtained. The statistic results were obtained by comparison and analysis. According to the results of analysis, the seismic capacity of kinds of typical buildings in this region was provided: reinforced concrete frame structure showed fine seismic capability in all previous earthquake whose seismic damage was the slightest in the real statistics results; secondly were those of masonry and mortised timber frame buildings; the seismic damage of buildings, which was combined with timber frame and soil, stone, brick walls was the most serious.

Seismic Resistant Capability for Different Types of Brick-Wall Buildings in Taipei Basin

The buildings wall systems in Di-Hwa Street of Taipei, is quite different with the other historic area houses. In which the wall of building are made by different materials, such as earthen brick wall, stone brick wall, clay kiln brick wall, and their combination with un-regular types. The practicality of the proposed methodology is demonstrated through the Etabs software package analyzing the equivalent diagonal bracing models of each wall systems and evaluating the seismic resistant capacity of the brick wall structure. According to the analysis results, the seismic response control in displacement was observed. The seismic resistant capability of all of the brick wall structure, which were not enough to satisfied the design specification requirement according to the Ministry of Interior. also further increase the implementation of the improve devices on the displacement control of buildings is necessary.

Seismic Fragility Analysis of Mid-Story Isolation and Reduction Structures Based Two Directions

This study focus on derivation of such fragility curves using classic mid-story isolation and reduction structures (MIRS) in China metropolis. This study focus on derivation of such fragility curves using conventional industrial frames with masonry infill wall. A set of stochastic earthquake waves compatible with the response spectrum of China seismic code selected to represent the variability in ground motion. Dynamic inelastic time history analysis was used to analyze the random sample of structures. MIRS seismic capability of longitudinal and transversal orientation is different. Stochastic damage scatter diagrams based different seismic intensity index are obtained. Seismic fragility of longitudinal axis (Y axis) is larger than transversal axis (X axis) of frames under major earthquake obviously.

Seismic Fragility Analysis of RC Industrial Frames Based Stochastic Vibration

This study focus on derivation of such fragility curves using conventional industrial frames with masonry infill wall. A set of stochastic earthquake waves compatible with the response spectrum of China seismic code selected to represent the variability in ground motion. Dynamic inelastic time history analysis was used to analyze the random sample of structures. Industrial structural seismic capability of longitudinal and transversal orientation is different. Stochastic damage scatter diagrams based different seismic intensity index are obtained. Seismic fragility of longitudinal axis (X axis) is larger than transversal axis (Y axis) of frames under major earthquake obviously.

Seismic Performance of a Four-Decade-Old Overpass in Southeast Idaho

AbstractFollowing major earthquakes in the 1970s, 1980s, and 1990s, changes were made to the structural seismic design codes. Structures constructed prior to these revisions need to be evaluated for seismic vulnerability. The US-89 Overpass in Montpelier, Idaho, built in 1971, is the subject of this study. The current seismic design guides were used in conjunction with Open System for Earthquake Engineering Simulation (OpenSees), an advanced finite element computer modeling program, to perform nonlinear analyses of the bridge structure under four displacement time histories. The results show failure of the elements that restrain the lateral movement of the bridge deck. However, the lateral relative displacement between the superstructure and the top of the piers reach a maximum of 11.2 cm (4.4 in.), which is not enough to remove the superstructure from the 1.8 m (6 ft) wide seat. The work presented herein enhances seismic analysis capabilities for existing Idaho bridges and provides valuable information r...

Characterization of elastic properties of near-surface and subsurface deepwater hydrate-bearing sediments

Hydrate-bearing sands and shallow nodular hydrate are potential energy resources and geohazards, and they both need to be better understood and identified. Therefore, it is useful to develop methodologies for modeling and simulating elastic constants of these hydrate-bearing sediments. A gas-hydrate rock-physics model based on the effective medium theory was successfully applied to dry rock, water-saturated rock, and hydrate-bearing rock. The model was used to investigate the seismic interpretation capability of hydrate-bearing sediments in the Gulf of Mexico by computing elastic constants, also known as seismic attributes, in terms of seismic interpretation, including the normal incident reflectivity (NI), Poisson’s ratio (PR), P-wave velocity ([Formula: see text]), S-wave velocity ([Formula: see text]), and density. The study of the model was concerned with the formation of gas hydrate, and, therefore, hydrate-bearing sediments were divided into hydrate-bearing sands, hydrate-bearing sands with free gas in the pore space, and shallow nodular hydrate. Although relations of hydrate saturation versus [Formula: see text] and [Formula: see text] are different between structures I and II gas hydrates, highly concentrated hydrate-bearing sands may be interpreted on poststack seismic amplitude sections because of the high NI present. The computations of elastic constant implied that hydrate-bearing sands with free gas could be detected with the crossplot of NI and PR from prestack amplitude analysis, and density may be a good hydrate indicator for shallow nodular hydrate, if it can be accurately estimated by seismic methods.

Analysis of Structural Parameters of MSCS on of the Overall Failure Probability of the Structure

The randomness of value of tuned sub-structure mass and rigidity is comparatively large because of the needs of actual projects. Based on the dynamic characteristics and reliability of MSCS, the seismic response of the mega structure and the overall failure probability are discussed with the value of tuned sub structural mass and rigidity under different seismic intensity. It is shown that tuned sub structural mass and rigidity have significant affection on the overall reliability of structure, and seismic intensity has not interfere this regular pattern. Therefore, structural parameters of optimization which are referred to the regular pattern should be considered in the actual design in order to further enhance seismic capability of MSCS.

Experimental Studies on Seismic Performance of High Strength Reinforced Concrete Columns

This paper summarized an experimental study on seismic behavior of high strength steel reinforced high strength concrete columns under horizontal cyclic loading. Influencing factors of 14 columns included axial compression ratio, shape of hoops, shear span ratio, stirrup ratio, strength of concrete and stirrups, etc. Influence of seismic capacity and performance of columns by these factors were involved in. It indicates that high-strength stirrups could improve seismic capability of member availability.