scholarly journals Assessment and Code Considerations for the Combined Effect of Seismic Base Isolation and Viscoelastic Dampers

2011 ◽  
Vol 2011 ◽  
pp. 1-10 ◽  
Author(s):  
Aykut Erkal ◽  
Semih S. Tezcan ◽  
Debra F. Laefer
Keyword(s):  
Base Isolation ◽  
Time History ◽  
Earthquake Ground Motion ◽  
Soil Conditions ◽  
Base Case ◽  
Seismic Load ◽  
Bending Moments ◽  
Viscoelastic Dampers ◽  
Turkish Earthquake Code ◽  
The Impact

To propose an initial formulation for the passive control section of the Turkish Earthquake Code, the impact of base isolation and viscoelastic dampers on a four-storey reinforced concrete (RC) frame building was considered under various one-dimensional quake excitations. Both statically equivalent seismic load methods (comparing Turkish Earthquake code with Uniform Building Code) and linear time history analyses were applied to the RC building based on a portion of the 1999 Kocaeli Earthquake ground motion record (modified to possess predominant spectral periods of  sec and  sec representing hard and soft soil conditions, resp.). Effective peak ground acceleration was set to 0.40 g. Time history variations of upper column dis-placements and bending moments were compared, as well as storey drift ratios. Reductions of the fixed-base case column bending moments were obtained of up to 73% under base isolation, up to 25% with viscoelastic dampers, and up to 83% (with a unified response reduction factor) when both devices were both present.

Dynamic Characteristics of Base-Isolated Steel Frame under Seismic Ground Motion

2011 ◽  
Vol 255-260 ◽  
pp. 2341-2344
Author(s):  
Mohammad Saeed Masoomi ◽  
Siti Aminah Osman ◽  
Ali Jahanshahi
Keyword(s):  
Ground Motion ◽  
Base Isolation ◽  
Time History ◽  
Steel Structure ◽  
Steel Structures ◽  
Steel Frame ◽  
Nonlinear Time History Analysis ◽  
Seismic Load ◽  
Vector Method ◽  
Seismic Ground Motion

This paper presents the performance of base-isolated steel structures under the seismic load. The main goals of this study are to evaluate the effectiveness of base isolation systems for steel structures against earthquake loads; to verify the modal analysis of steel frame compared with the hand calculation results; and development of a simulating method for base-isolated structure’s responses. Two models were considered in this study, one a steel structure with base-isolated and the other without base-isolated system. The nonlinear time-history analysis of both structures under El Centro 1940 seismic ground motion was used based on finite element method through SAP2000. The mentioned frames were analyzed by Eigenvalue method for linear analysis and Ritz-vector method for nonlinear analysis. Simulation results were presented as time-acceleration graphs for each story, period and frequency of both structures for the first three modes.

Seismic Isolation of Buildings Subjected to Typical Subduction Earthquake Motions for the Mexican Pacific Coast

1997 ◽  
Vol 13 (3) ◽  
pp. 505-532 ◽  
Author(s):  
Arturo Tena-Colunga ◽  
Consuleo Gómez-Soberón ◽  
Abel Mun~oz-Loustaunau
Keyword(s):  
Dynamic Stability ◽  
Pacific Coast ◽  
Base Isolation ◽  
Time History ◽  
Mode Shapes ◽  
Soil Conditions ◽  
Original Design ◽  
Mexican Pacific ◽  
Fixed Base ◽  
Isolation Systems

An analytical study on the application of different base isolation systems for original design or retrofit of typical building structures of the Mexican Pacific Coast is presented. The subject hypothetical buildings are located on hard soil conditions at Acapulco. Typical accelerograms for the Mexican subduction zone recorded during recent earthquakes were used for 3-D time-history analyses. Bidirectional input was used for the time-history analyses. The studied base isolation systems reported in this study are lead-rubber bearings (LRB) and steel-hysteretic dampers (SHD). For the original design case studies, the superstructures were designed: a) according to the seismic provisions of the building code of Guerrero state (RCGS-90) for the fixed-base condition and, b) according to an elastic design based upon a 3-D lateral force distribution consistent with dominant mode shapes for the isolated structure to yield the peak dynamic base shear transmitted by the isolation system. Material volumes for the superstructure were estimated for both the fixed-base code designs and the base-isolation designs. Important savings on the volume of concrete and steel reinforcement can be attained for the base isolated designs with respect to their counterpart fixed-base designs. Dynamic responses for the isolated structures compare favorably with those for the fixed-base structures. The study confirms many findings published in the literature regarding the effectiveness of base isolation and the effect of torsional responses. However, the study also shows that the dynamic stability of isolators is not always achieved using rational design procedures. The dynamic stability and design of the studied base isolators can be controlled by acceleration records associated to moderate earthquakes when these records are near the fault plane and by torsional responses.

scholarly journals Seismic Isolation System using U-Shaped Steel Damper

2019 ◽  
Vol 8 (4) ◽  
pp. 12336-12339
Keyword(s):  
Seismic Isolation ◽  
Base Isolation ◽  
Structural Response ◽  
Time History ◽  
Earthquake Ground Motion ◽  
Isolation System ◽  
Isolation Technique ◽  
Base Isolation System ◽  
The Time Domain ◽  
External Forces

In the present paper base isolation system is analyzed and its seismic behavior is investigated using U-shaped steel dampers as an isolator by placing it at the bottom of the structure. It is the most popular way of protecting the structure using control techniques for earthquake ground motion. The dampers significantly reduced damage factors such as displacement and drift. To reduce structural response to external forces, which can be accomplished through the use of special protective systems. So to prevent these damages, seismic isolation technique can be used for newly constructed structures. The time history analysis of the time domain on this structure is conducted by using SAP2000 software

A Study of Fluid-Structure Coupled Analysis for Large LNG Storage Tanks in Consideration of Uplift

2011 ◽  
Author(s):  
Shoichiro Hayashi ◽  
Tomoyo Taniguchi ◽  
Akira Umeda ◽  
Hisayuki Yamada ◽  
Takumi Kawasaki ◽  
...  
Keyword(s):  
Plate Thickness ◽  
Time History ◽  
Fem Analysis ◽  
Coupled Analysis ◽  
Soil Conditions ◽  
Seismic Load ◽  
Storage Tanks ◽  
Base Shear ◽  
Fluid Structure ◽  
Tank Design

With the rising demand for LNG in recent years, expansion of existing LNG terminals and construction of new ones are planned in many places around the world, and some of such projects are already in progress. Sites selected for these projects may not necessarily have favorable soil conditions from the viewpoint of seismic protection. Seismic demand tends to be higher for LNG storage tanks to be built on such sites. Severe seismic deign conditions require precise estimation of the uplift at the annular part during the earthquake. Depending on the estimation results, either of the following measures needs to be taken: increase of the plate thickness; installation of anchors or seismic isolators; and, occasionally, modification of the tank proportion. Uplift estimation is usually based on conventional design methods in which seismic load is converted into static load, because dynamic behavior of uplift is hardly taken into account in the design process due to its complexity. Some previous fundamental studies revealed that tank uplift and other dynamically induced responses would tend to be smaller than those simulated by static loads. This indicates a possibility of optimizing tank structure based on these research results. As a step toward introducing the uplift response in tank design properly, a time-history FEM analysis with fluid-structure coupling was carried out to understand the tank uplift behavior. This paper reports the findings from the analysis, including comparison with conventional analysis and previous fundamental studies. Since the rocking response may reduce overturning moment and base shear of tanks, structural design may have benefits if such mechanisms are properly taken into account.

SPECIFICS OF PERFORMING SEISMIC MICROZONING IN THE URBANIZED COASTAL AREA OF GELENDZHIK CITY FOR HIGH-RISE CONSTRUCTION

2018 ◽  
Vol 12 (5-6) ◽  
pp. 82-90 ◽  
Author(s):  
B. A. Trifonov ◽  
V. V. Sevost'yanov
Keyword(s):  
Weighted Average ◽  
Seismic Intensity ◽  
The Black Sea ◽  
Soil Conditions ◽  
Seismic Load ◽  
Seismic Microzoning ◽  
Good Convergence ◽  
S Waves ◽  
The Impact ◽  
Seismic Impacts

The initial (background) seismicity of the territory of Gelendzhik with the high responsibility buildings projected for construction of (35-storey towers 123 meters high) is equal to 9 points according to the Map of General Seismicity of Russia (OSR-2015(B)) with the period of recurrence of tremors 1 time per 1000 years. The purpose of the study was to obtain the parameters of predictive seismic impacts for the site of the proposed construction taking into account regional seismotectonic and local seismic soil conditions. The influence of ground conditions on the on the seismicity of the research site was estimated when the bedrock in the Black Sea coast of the Caucasus, as a rule, lies not deep (several meters) from the surface and overlapping Quaternary sediments are flooded. Based on the result of vertical seismic profiling (VSP), a generalized geoseismic condition for the whole site was given. To determine the seismic intensity increment ΔI by the method of seismic rigidities comparison, the weighted average values of the S-waves velocities and the thickness of the soils up to the boundary of the reference soil were used in the calculations. Based on the obtained geoseismic model (results of engineering-geological and seismic studies), the NERA program calculated the parameters of seismic impacts from the most hazardous zones of origin of seismic foci (ASF) taking into account the initial seismic impacts in the territory of Gelendzhik and the results of seismic microzoning. It was found that the highest values of maximum accelerations at the studied site are caused by foci from the Mikhailovskaya and Gelendhizkskaya ASF zones; and the lower values are expected from outbreaks from the Tyapsinskaya and Akhtyrskaya ASF zones. To calculate the seismic load on the projected structures, it is proposed to use one set of synthesized accelerograms (X, Y, Z) simulating the impact from different PSF zones, which contain the entire set of vibration periods and cover the whole range of maximal velocities dangerous for the studied areas. The analysis obtained data shows good convergence of the seismic microzoning data obtained by the calculation method and seismic rigidity method.

Impact of roof shading on building energy performance in warm & humid climatic places of India

2020 ◽  
pp. 50-64
Author(s):  
Kuladeep Kumar Sadevi ◽  
Avlokita Agrawal
Keyword(s):  
Energy Consumption ◽  
Energy Conservation ◽  
Energy Performance ◽  
General Assumption ◽  
Climatic Conditions ◽  
Building Envelope ◽  
Passive Cooling ◽  
Base Case ◽  
U Value ◽  
The Impact

With the rise in awareness of energy efficient buildings and adoption of mandatory energy conservation codes across the globe, significant change is being observed in the way the buildings are designed. With the launch of Energy Conservation Building Code (ECBC) in India, climate responsive designs and passive cooling techniques are being explored increasingly in building designs. Of all the building envelope components, roof surface has been identified as the most significant with respect to the heat gain due to the incident solar radiation on buildings, especially in tropical climatic conditions. Since ECBC specifies stringent U-Values for roof assembly, use of insulating materials is becoming popular. Along with insulation, the shading of the roof is also observed to be an important strategy for improving thermal performance of the building, especially in Warm and humid climatic conditions. This study intends to assess the impact of roof shading on building’s energy performance in comparison to that of exposed roof with insulation. A typical office building with specific geometry and schedules has been identified as base case model for this study. This building is simulated using energy modelling software ‘Design Builder’ with base case parameters as prescribed in ECBC. Further, the same building has been simulated parametrically adjusting the amount of roof insulation and roof shading simultaneously. The overall energy consumption and the envelope performance of the top floor are extracted for analysis. The results indicate that the roof shading is an effective passive cooling strategy for both naturally ventilated and air conditioned buildings in Warm and humid climates of India. It is also observed that a fully shaded roof outperforms the insulated roof as per ECBC prescription. Provision of shading over roof reduces the annual energy consumption of building in case of both insulated and uninsulated roofs. However, the impact is higher for uninsulated roofs (U-Value of 3.933 W/m2K), being 4.18% as compared to 0.59% for insulated roofs (U-Value of 0.33 W/m2K).While the general assumption is that roof insulation helps in reducing the energy consumption in tropical buildings, it is observed to be the other way when insulation is provided with roof shading. It is due to restricted heat loss during night.

The methodological approach for the determination of the pressure of artificial raindrops as a question of the theory of splash soil erosion

2020 ◽  
pp. 24-28
Author(s):  
Mihail Zver'kov
Keyword(s):  
Block Diagram ◽  
Methodological Approach ◽  
Control Measures ◽  
Soil Conditions ◽  
Effective Pressure ◽  
Long Distance ◽  
Splash Erosion ◽  
Rain Drops ◽  
Artificial Rain ◽  
The Impact

To the article the results of the theoretical and experimental researches are given on questions of estimates of the dynamic rate effect of raindrop impact on soil. The aim of this work was to analyze the current methods to determine the rate of artificial rain pressure on the soil for the assessment of splash erosion. There are the developed author’s method for calculation the pressure of artificial rain on the soil and the assessment of splash erosion. The study aims to the justification of evaluation methods and the obtaining of quantitative characteristics, prevention and elimination of accelerated (anthropogenic) erosion, the creation and the realization of the required erosion control measures. The paper considers the question of determining the pressure of artificial rain on the soil. At the moment of raindrops impact, there is the tension in the soil, which is called vertical effective pressure. It is noted that the impact of rain drops in the soil there are stresses called vertical effective pressure. The equation for calculation of vertical effective pressure is proposed in this study using the known spectrum of raindrops. Effective pressure was 1.4 Pa for the artificial rain by sprinkler machine «Fregat» and 5.9 Pa for long distance sprinkler DD-30. The article deals with a block diagram of the sequence for determining the effective pressure of rain drops on the soil. This diagram was created by the author’s method of calculation of the effective pressure of rain drops on the soil. The need for an integrated approach to the description of the artificial rain impact on the soil is noted. Various parameters characterizing drop erosion are considered. There are data about the mass of splashed soil in the irrigation of various irrigation machinery and installations. For example, the rate (mass) of splashed soil was 0.28…0.78 t/ha under irrigation sprinkler apparatus RACO 4260–55/701C in the conditions of the Ryazan region. The method allows examining the environmental impact of sprinkler techniques for analyzes of the pressure, caused by raindrops, on the soil. It can also be useful in determining the irrigation rate before the runoff for different types of sprinkler equipment and soil conditions.

scholarly journals Autism Tsunami: the Impact of Rising Prevalence on the Societal Cost of Autism in the United States

2021 ◽  
Author(s):  
Mark Blaxill ◽  
Toby Rogers ◽  
Cynthia Nevison
Keyword(s):  
Forecast Model ◽  
The United States ◽  
Population Projections ◽  
Base Case ◽  
Prevention Strategies ◽  
Total Base ◽  
Cost Categories ◽  
The Cost ◽  
The Impact ◽  
First Time

AbstractThe cost of ASD in the U.S. is estimated using a forecast model that for the first time accounts for the true historical increase in ASD. Model inputs include ASD prevalence, census population projections, six cost categories, ten age brackets, inflation projections, and three future prevalence scenarios. Future ASD costs increase dramatically: total base-case costs of $223 (175–271) billion/year are estimated in 2020; $589 billion/year in 2030, $1.36 trillion/year in 2040, and $5.54 (4.29–6.78) trillion/year by 2060, with substantial potential savings through ASD prevention. Rising prevalence, the shift from child to adult-dominated costs, the transfer of costs from parents onto government, and the soaring total costs raise pressing policy questions and demand an urgent focus on prevention strategies.

scholarly journals Impact of Passive Energy Efficiency Measures on Cooling Energy Demand in an Architectural Campus Building in Karachi, Pakistan

2021 ◽  
Vol 13 (13) ◽  
pp. 7251
Author(s):  
Mushk Bughio ◽  
Muhammad Shoaib Khan ◽  
Waqas Ahmed Mahar ◽  
Thorsten Schuetze
Keyword(s):  
Energy Efficiency ◽  
Energy Demand ◽  
Electricity Consumption ◽  
Information Modeling ◽  
Base Case ◽  
Energy Efficiency Measures ◽  
Efficiency Measures ◽  
The Impact ◽  
Cooling Energy Demand ◽  
Campus Building

Electric appliances for cooling and lighting are responsible for most of the increase in electricity consumption in Karachi, Pakistan. This study aims to investigate the impact of passive energy efficiency measures (PEEMs) on the potential reduction of indoor temperature and cooling energy demand of an architectural campus building (ACB) in Karachi, Pakistan. PEEMs focus on the building envelope’s design and construction, which is a key factor of influence on a building’s cooling energy demand. The existing architectural campus building was modeled using the building information modeling (BIM) software Autodesk Revit. Data related to the electricity consumption for cooling, building masses, occupancy conditions, utility bills, energy use intensity, as well as space types, were collected and analyzed to develop a virtual ACB model. The utility bill data were used to calibrate the DesignBuilder and EnergyPlus base case models of the existing ACB. The cooling energy demand was compared with different alternative building envelope compositions applied as PEEMs in the renovation of the existing exemplary ACB. Finally, cooling energy demand reduction potentials and the related potential electricity demand savings were determined. The quantification of the cooling energy demand facilitates the definition of the building’s electricity consumption benchmarks for cooling with specific technologies.

scholarly journals Seismic Performance of a Green Roof Structure

2021 ◽  
Vol 13 (8) ◽  
pp. 4278
Author(s):  
Svetlana Tam ◽  
Jenna Wong
Keyword(s):  
Green Roof ◽  
Time History ◽  
Green Roofs ◽  
Moment Frame ◽  
Steel Moment Frame ◽  
Roof Structure ◽  
Nonlinear Time History Analyses ◽  
Vegetated Roofs ◽  
Nonlinear Time History ◽  
The Impact

Sustainability addresses the need to reduce the structure’s impact on the environment but does not reduce the environment’s impact on the structure. To explore this relationship, this study focuses on quantifying the impact of green roofs or vegetated roofs on seismic responses such as story displacements, interstory drifts, and floor level accelerations. Using an archetype three-story steel moment frame, nonlinear time history analyses are conducted in OpenSees for a shallow and deep green roof using a suite of ground motions from various distances from the fault to identify key trends and sensitivities in response.

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