Earthquake-resistant Capacity Research Articles

The influence of boundary conditions on nonlinear time domain site response analysis using LS-DYNA

The dynamic response of nuclear power plants and other critical infrastructure under seismic conditions is a major issue, and the earthquake-resistant capacity design of such facilities and their interior equipment should be based on prediction of dynamic response. Therefore, field geological investigations and corresponding site response analyses facilitate the evaluation of seismic site effects for the entire construction process, including site selection and detailed design. During site response analysis, soil parameters are usually obtained from laboratory tests using specimens retrieved from boreholes or from empirical equations. Conventional site response analysis software assumes horizontal layering in a 1D soil model, though the actual conditions of underground stratification are far more complicated. Some research efforts have undertaken 3D site response and soil-structure interaction analysis using LS-DYNA; however, the influence of different boundary conditions in these studies has been rarely discussed. The research reported on in this paper utilized LS-DYNA to perform nonlinear time-domain site response analysis and evaluated the difference between 1D and 3D model results. The results of both 1D and 3D site response analyses conducted using LS-DYNA were comparable to those of traditional approaches using a constrained boundary. The 3D models that adopt a non-reflective boundary condition can be affected by energy attenuation near the model boundary, causing a significant difference in the results. We suggest that the constructed model should have an area of at least 600 m × 600 m (plan view) to ensure accuracy in a 200 m × 200 m area in the center of the 3D simulation model using non-reflecting boundary conditions. Furthermore, four soil profile from real sites have been verified that the suggestion is also applicable in multilayered scenario.

Effectiveness of buckling restrained braces for upgrading earthquake resistant capacity of single layer grid dome

This study investigates the effectiveness of buckling restrained braces (BRBs) adopted for reducing dynamic responses of a grid dome to severe earthquakes. The diameter of the dome is 120 m of a circular plan. The dome is supported by a ductile substructure composed of BRBs, and the substructure is proportioned so as to initially yield under a base shear coefficient of approximately 0.30 and to bear a base shear coefficient of 0.40 against earthquake motions of the ultimate limit state. Artificial seismic accelerations based on a design spectrum specified in a Japanese code are applied in the present analysis. The intensity of the applied accelerations ranges from the serviceability limit level to the ultimate limit level. The results of responses have provided us with valuable information indicating that the ductile substructure of the dome absorbs seismic energy with a stable hysteresis loop, significantly decreasing the responses of the dome. The responses also show that the dynamic amplification within the dome is greatly suppressed in comparison with those in domes supported by elastic substructures. A formulation for the response reduction rate is proposed. The present paper clearly indicates the feasibility of constructing large reticulated domes of this type in regions prone to severe seismicity using such BRBs.

Seismic performance of a load-bearing prefabricated composite wall panel structure for residential construction

To improve both seismic performance and thermal insulation of low-rise housing in rural areas of China, this study proposes a load-bearing prefabricated composite wall panel structure that achieves appropriate seismic performance and energy efficiency using field-assembled load-bearing prefabricated composite wall panels. A 1:2 scale prototype built using load-bearing prefabricated composite wall panel is subjected to quasi-static testing so as to obtain damage characteristics, load-bearing capacity and load–displacement curves in response to a simulated earthquake. As a result, seismic performance indicators of load-bearing capacity, deformation and energy-dissipating characteristics, are assessed against the corresponding seismic design requirements for rural building structures of China. Experimental results indicate that the earthquake-resistant capacity of the prototype is 68% higher than the design value. The sample has a ductility factor of 4.7, which meets the seismic performance requirement mandating that the ductility factor of such concrete structures should exceed 3. The design can be further optimized to save the consumption of material. This shows that the load-bearing prefabricated composite wall panel structure developed here has decent load-bearing capacity, ductility and energy dissipation abilities, a combination of which is in line with the seismic design code. A new construction process proposed here based on factory prefabrication and field assembly leads to a considerable reduction of energy consumption.

Comparative Study of Nonlinear Static and Time-History Analyses of Typical Korean STS Container Cranes

Ship-to-shore (STS) container gantry cranes, used at terminals for loading and unloading containers from a ship, are an important part of harbor structures. The size and weight of modern STS container cranes are increasing to satisfy the demand for bigger ships. This is expected to result in more lateral load when excited by seismic motions. The existing Korean STS container cranes did not behave properly during several recent moderate earthquakes in South Korea. Typical Korean STS container cranes must be checked for the earthquake-resistant capacity. In this research, two nonlinear static analyses procedures, also known as pushover analyses, commonly used for seismic design of buildings, namely, capacity spectrum method and equivalent linearization method, are comprehensively studied to check their suitability for studying seismic behavior of STS cranes. Results obtained by these two nonlinear static analysis methods are then compared with the results obtained by nonlinear time-history analyses of the STS cranes by exciting them with nine recorded earthquake time histories around worldwide. The behaviors of the cranes are analyzed in terms of the total base shear, drift, and base uplift. The comparisons indicate that the nonlinear static methods can be appropriate for estimating the total base shear and drift of the portal frame of a container crane. The pushover analyses also provide information on performance levels as defined in ASCE/SEI 41-13, of a typical Korean STS container crane. Furthermore, it is observed that the uplift response of the crane is strongly influenced by the duration of an earthquake.

Arrangement of Connections and Piers and Earthquake Resistant Capacity of Typical Bridges

Arrangement of Connections and Piers and Earthquake Resistant Capacity of Typical Bridges

Shaking Table Test Analysis of Bottom-Business Multi-Story Masonry Structure in Small and Middle Towns in the Southward

Bottom-business multi-story masonry structure is widely used in small and middle towns in the southward in China. In the downtown of Beichuan county which affected by Wenchuan earthquake, more than 80% of this kind of building collapsed. But the Apartment of Beichuan Telecommunication Bureau behaved well earthquake resistant capacity with a moderate damage in the earthquake. The obvious difference between this building and others is the setting of winged columns in the front longitudinal wall of the first floor. For proving the influence of these members in the structure seismic capacity, the earthquake simulation shaking table test of 2 1/5 reduced scale models were designed and carried out. The models dynamic response, acceleration, displacement and strain were measured and collected, that model with winged columns behave well was testified. And the reinforcement method of balancing stiffness and increasing ductility is put forward. The results provide a foundation for the retrofitting design of the existing houses.

Seismic Analysis of a Masonry Residential Building in Wenchuan Earthquake

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.

A Study of New Type of Earthquake-Resistant and Crack-Resistant Block

Lightweight concrete blocks, when under the affection of earthquake, will cause negative affection on the performance of the frame structure[1], but many designers will only take the calculation method into consideration with the neglect of the design of the block structure. This article, which summarizes some previous studies, has designed a new type earthquake-resistant and crack-resistant Block, which is formed by the base block and rubber integrated earthquake-resistant block. This kind of block filled wall, which is similar to viscous damper,will reduce the negative affection on the performance of the frame structure and enhance the frame structure of the earthquake-resistant capacity. By the coordinating of earthquakereducing convex block and earthquake reducing trench on the base, interact links between the block will be strengthened, so that to strengthen the crack-resistant capacity of the wall.

Elastic Results’ Comparison between Computing and Test of a Scaled Model of a Complex Supertall Building

The height of a complex supertall building is 250m. The central RC tube and peripheral SRC frame with a strengthened truss and a transfer truss are employed to resist vertical and lateral loads. At first, a shaking table test was performed on a 1/30 scaled model of the building to study its dynamic characteristics and to evaluate its earthquake resistant capacity. Then, a 3D finite element analysis of model structure was carried out. Finally, the analytical results were compared with the experimental ones to gain a better understanding of the structural behavior.

Consideration of Improving Earthquake Resistant Capacity of Earth Buildings

Earth building is one kind of residential buildings with typical characteristics of materials used locally, natural existence, reasonable construction and low cost in Hanzhong country, and it includes wisdom of working people, and contains plentiful ecological concept, previous architecture experience. The major defect is its low anti-seismic performance, suggestions improving the earthquake resistant capacity of raw-soil structures are put forward from the aspects of enhancing strength and connection, and the preferences for the socialist new rural construction after seismic disasters are provided in the end.

Studies on Seismic Demand Spectra Based on Strength Reduction Factor

For resolving the practical problem about bridge structures, according to the seismic damage regularity and the structural characteristics, the capacity design method of bridge structure was introduced. In order to account synthetically for the influence factors and convert the inelastic seismic design method into the pseudo-static method, which is easily accepted by engineers, the strength reduction factor was commonly used in seismic design of structures. Based on the principles of the inelastic spectrum established by using the relationship between the strength reduction factor R and ductility factor μ, the seismic demand spectra were obtained from the design spectrum of the Highway Engineering Seismic Design Code (JTJ 004-89). This will be beneficial to the earthquake-resistant capacity design in practical bridge structures.

A Rapid Seismic Evaluation Method of Masonry Buildings Based on Earthquake Damage

Wall and tie column shear strength of every floor in masonry buildings as indicators of earthquake-resistant capacity, the evaluation criteria of the indicators was obtained based on the earthquake damage analysis on the 72 multi-storey masonry buildings in Dujiangyan and Hanwang areas. Based on these tests, a rapid seismic evaluation method of masonry buildings was proposed, this method can assess the degree of earthquake damage for the masonry structure under the level of seismic intensity directly. The application of the method is introduced by analyzing the earthquake damage of a masonry building in Wenchuan earthquake. The results show that the method can evaluate the aseismic performance for masonry buildings, and can assess the degree of earthquake damage additionally.

Shaking table model test and numerical analysis of a supertall building with high‐level transfer storey

SUMMARYThe seismic behaviour of a 53‐storey tower with the height of 250 m is investigated in this paper. This supertall building is composed of a reinforced core, two outrigger trusses (a strengthened storey at 20th ∼ 21st floor and a high‐level transfer storey at 37th ∼ 38th floor) and eight composite (steel‐encased concrete) mega‐columns below the high‐level transfer storey in the exterior perimeter of the building. Due to the discontinuity of the eight composite mega‐columns, they are replaced by 33 upper‐close columns at the 37th ∼ 38th level. This paper describes tests performed on a 1/30 scaled model of the building to study its dynamic characteristics and to evaluate its earthquake resistant capacity. The model test results indicate that the prototype structure is able to withstand an earthquake of intensity 7 without severe damage. In addition, a 3D finite element analysis of model structure was carried out and the analytical results were compared with the experimental ones to gain a better understanding of the structural behaviour. Copyright © 2010 John Wiley & Sons, Ltd.

Seismic and Wind Performance of Five-Storied Pagoda of Timber Heritage Structure

In Japan, there exist a total of 22 five-storied timber pagodas constructed before the middle of 19 centuries. All of those pagodas are registered as the important cultural heritages by Japanese Government, while some of them are listed in World Cultural Heritages such as Horyu-ji Temple’s Pagoda that was built in the end of 7th century. As those timber pagodas in seismic areas have survived against earthquakes during their long histories, their earthquake resistant capacity has been studied for a century. However, the actual dynamic behaviors of timber pagodas subjected to large earthquakes should be recorded to understand the seismic performance. Furthermore, an interesting structural issue has recently risen of wind resistant capacity of traditional five-storied timber pagodas, as such tall timber structures may be severely affected by strong wind. In order to record the actual dynamic behaviors during not only earthquakes but also typhoons, we have been conducting earthquake and wind monitoring at Hokekyou-ji Temple in Ichikawa City, next to Tokyo, which has survived for 4 centuries against not only large earthquakes but also severe typhoons. Hence, while the earthquake monitoring has been done by the conventional method utilizing accelerometers, the dynamic displacement of the structural response to wind has been directly measured by a new technique employing an image process system using LED makers and CCD camera, because the wind response includes much longer period component in general, therefore, it must be difficult to measure accurately the wind response by accelerometers. The scope of the present paper are 1) to review the past studies to understand the excellent earthquake resistance of five-storied timber pagodas, as well as, to introduce our research project of seismic and wind monitoring that has been successfully conducted since 2007, 2) to interpret those monitoring records which would be useful for understanding seismic and wind performance of the heritage timber pagodas that have survived for many centuries with describing the simulation analysis of seismic response, and 3) to show the long term monitoring records of the horizontal displacement of the heritage structure.

Earthquake proof efficacy of Velocity and Displacement Dependent Hydraulic Damper (VDHD) for R.C. structures

AbstractThe objective of this research is to study whether a Velocity and Displacement Dependent Hydraulic Damper (VDHD) will provide effective damping without increasing the acceleration response of a reinforced concrete structure during an earthquake before the yield strength is reached. The study also includes whether this device will provide hysteretic energy after the yield strength is reached to effectively lower the structural displacement reaction. The efficiency of VDHD is confirmed using a nonlinear numerical model developed by the authors for carrying out numerical analyses of three dampers, i.e. Viscous Damper (VD), Bulking Resistant Bracing (BRB) and VDHD, to study the response of structures excited by earthquake and to compare model parameters based on their seismic performance. The results indicate that when a reinforced concrete structure is subject to near‐fault earthquake for various durations, VDHD has a better structural displacement response capability than either VD or BRB with a medium efficiency to suppress the acceleration response between VD and BRB. These observations conform to the theoretical predications thus verifying the capability of VDHD to lower the displacement and acceleration responses of a reinforced concrete structure during earthquake. The results presented in this paper illustrate the earthquake resistant capacity of VDHD to protect reinforced concrete structures. Copyright © 2008 John Wiley & Sons, Ltd.

Evaluation of earthquake resistant capacity with nonlinear analysis of the rigid frame steel bridges

Evaluation of earthquake resistant capacity with nonlinear analysis of the rigid frame steel bridges

A Study to Improve Earthquake Resistant Capacity of Steel Gable Truss Structures by Applying Hysteresis Dampers to the Column Bases

A Study to Improve Earthquake Resistant Capacity of Steel Gable Truss Structures by Applying Hysteresis Dampers to the Column Bases

CONVERSION PROCESS OF FARMERY'S BARN TO THE SCHOOLCHILD CARE FACILITY

The authors had an opportunity to take part in the project of regenerating the traditional wooden barn to schoolchild clubhouse, and made the master plan and executive design. The earthquake-resistant capacity was lower than safety standard as the result of performance diagnosis. Reinforcement design of earthquake-resistant capacity was held based on the result and utilization plan by adopting the original wooden double panel for resistant wall, and the improvement construction expensed the cost about 8,900,000 yen.

RENOVATION PROCESS OF TRADITIONAL WOODEN HOUSE TO THE WELFARE HOME BY THE FIXED-TERM RENTAL HOUSING CONTRACT

Authors got an opportunity to take part in the regenerated project to the welfare facility of traditional wooden house, and took charge of the decision of master plan and basic design. For this case, the verification of the validity of the improvement process is given. The same contract as the long-term contract method that authors proposed was concluded. Earthquake-resistant capacity is lower than safety standard as the result of performance diagnosis and low heat insulation performance of traditional wooden house was confirmed again. Design was held based on the result of the performance diagnosis and the utilization plan. Though improvement construction expensed the cost about 13,000,000 yen, the housing expenses expenditure of every month settled down within the range of the market house rent, and the validity of the improvement system by the periodic rented house form was shown.

Damage to Residential Retaining Walls at the Genkai-Jima Island Induced by the 2005 Fukuoka-Ken Seiho-Oki Earthquake

The 2005 Fukuoka-ken Seiho-oki earthquake caused heavy damage to residential areas at the Genkai-jima Island. A field survey was carried out to investigate the damage of retaining walls in the residential areas. From the survey of 218 retaining walls, it appeared that 83% of the retaining walls were damaged and 61% of the whole lost their functions (collapsed or distorted/cracked). Especially in masonry retaining walls using natural rocks and boulders, the damage was serious. The damage features of dry masonry retaining walls (collapsed: 62%) and wet masonry retaining walls (collapsed: 25%) were different, and the difference in the earthquake-resistant capacity between the two retaining walls became obvious. Moreover, it appeared that most of the residential houses are built on transitions of cut slopes and fill embankments. It seems that this condition is one of a great factor which causes the heavy damage. Only 17% of the retaining walls escaped from any damage. Furthermore, to evaluate the collapse mechanism of masonry retaining walls during earthquake, a theoretical model based on the earth pressure theory was proposed. Through the theoretical considerations, it became possible to quantitatively evaluate the stability of the masonry retaining walls.