Behavior of multidirectional friction dampers

2020 ◽  
Vol 26 (21-22) ◽  
pp. 1969-1979
Author(s):  
Recep Suk ◽  
Gökhan Altintaș
Keyword(s):  
Structural Damage ◽  
Load Capacity ◽  
Spherical Surface ◽  
Poor Performance ◽  
Surface Friction ◽  
Building Stock ◽  
Seismic Damper ◽  
Earthquake Performance ◽  
Production Techniques ◽  
Property Losses

Earthquakes are catastrophic events causing loss of lives, injuries, and extensive losses in properties. Majority of the life and property losses of earthquakes are dependent on the incapabilities of the building stock to resist earthquakes. Although unsuitable design, analyses, and production techniques play a major role as the main reasons for the poor performance of buildings against earthquakes, buildings constructed in accordance with building codes also suffer from the devastating impact of earthquakes. In this context, the lack of proper management and adequate damping of the energy caused by earthquakes is a major cause of structural damage in earthquakes. The efficiency of conventional basic elements in structures with energy damping is very limited and may not be sufficient for the damping of a large amount of earthquake-induced energy. Thanks to the rapid advances in technology and associated engineering techniques, numerous new products, and production and calculation techniques are underway to mitigate the devastating effects of earthquakes on buildings. In this study, it was aimed to theoretically and experimentally investigate the performance of a versatile friction-type seismic damper that eliminates earthquake energy. The damper is designed using a spherical surface friction joint to respond to all loads regardless of the loading direction. The damper can be easily adjusted to the desired capacity by means of bolt tensioning elements. Experiments have been carried out for various shear loads and damping parameters. Furthermore, numerical analysis of the model was carried out by use of the finite element method. The results of this study revealed that the shear load capacity of the device did not change at different frequencies. Analyzing the effect of the equipment on a structure, it was understood that it reduces roof displacement and periods of the structure. The analysis revealed that the damper significantly improved the earthquake performance of the structure.

scholarly journals Performance of RC and Masonry Structures During 2019 Durrës Earthquake

2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Marsed Leti
Keyword(s):  
Structural Damage ◽  
Structural Response ◽  
Poor Performance ◽  
Past Century ◽  
Masonry Structures ◽  
System Quality ◽  
Building Stock ◽  
Damage Level ◽  
Rc Building

Albania has suffered from major earthquakes in the past century that have caused varying levels of damage to buildings. As a result of the number of damaged buildings and loss of life, attention has focused mostly on the poor performance of reinforced concrete and masonry structures in low and mid-rise buildings. This paper presents the results of a reconnaissance visits to the disaster-stricken area in the Durrës region in Albania and covers many zones in the region where historical and modern buildings suffered serious structural damage or collapses during the November 26, 2019, Durrës Earthquake. Special emphasis was placed on masonry and RC buildings, since the damage level was high in these buildings. The consequences of the Durrës earthquake are important for similar masonry and RC building stock in other seismically vulnerable European cities. Regularity of the structural system, quality of the material utilized, the distribution of mass and stiffness through the building, the ratio of openings on masonry walls and diaphragm stiffness have a crucial influence on the structural response. Inappropriate interventions led to serious damage or collapses, resulting in casualties. Examples of numerous damage types, as witnessed during the site visits to the affected region are presented, along with technically explanation of causes for the damages.

Earthquake performance of collapsed school building under Van-Tabanli (Mw=7.2) earthquake

2018 ◽  
Vol 4 (4) ◽  
pp. 159
Author(s):  
Cumhur Cosgun ◽  
Atakan Mangir
Keyword(s):  
Structural Damage ◽  
Stock Assessment ◽  
Significant Proportion ◽  
School Building ◽  
Building Stock ◽  
Seismic Code ◽  
Existing Structures ◽  
Earthquake Performance ◽  
The Moment ◽  
Earthquake Effects

A majority of the present building stock of Turkey is under seismic risk. It is believed that a significant proportion of the existing structures will either collapse or will get heavily damaged during a possible strong earthquake. With this respect, as an initial stage in the betterment of the structurally deficient building stock, assessment of existing buildings is of vital importance. From this viewpoint, in this study, earthquake performance of a collapsed school building was investigated through numerical performance analysis based on codified rules. At the end of 2011, numerous ground motions of various intensities have been registered in city of Van in eastern Turkey starting from 23 October 2011. Two major earthquakes were experienced at the Tabanli and Edremit district of Van. The moment magnitudes of these earthquakes were announced as 7.2 and 5.6, respectively. The investigated school building in this study was located in the city of Van and collapsed after first major earthquake (Mw=7.2). Structural details of the load-bearing members of the investigated building including as-built drawings and specified material properties were obtained. Based on obtained data, a numerical model was created to simulate the behavior of the building under code specified earthquake effects. Earthquake performance assessment of the structure was carried based on the recommendations given in the related chapter of the Turkish Seismic Code. Pushover analyses were performed and expected member by member damage levels and overall structural damage were determined in accordance with Turkish Seismic Code. The results are discussed to enlighten the actual cause of the collapse.

Earthquake performance of collapsed school building under Van-Tabanli (Mw=7.2) earthquake

2018 ◽  
Vol 4 (4) ◽  
pp. 159
Author(s):  
Cumhur Cosgun ◽  
Atakan Mangir
Keyword(s):  
Structural Damage ◽  
Stock Assessment ◽  
Significant Proportion ◽  
School Building ◽  
Building Stock ◽  
Seismic Code ◽  
Existing Structures ◽  
Earthquake Performance ◽  
The Moment ◽  
Earthquake Effects

A majority of the present building stock of Turkey is under seismic risk. It is believed that a significant proportion of the existing structures will either collapse or will get heavily damaged during a possible strong earthquake. With this respect, as an initial stage in the betterment of the structurally deficient building stock, assessment of existing buildings is of vital importance. From this viewpoint, in this study, earthquake performance of a collapsed school building was investigated through numerical performance analysis based on codified rules. At the end of 2011, numerous ground motions of various intensities have been registered in city of Van in eastern Turkey starting from 23 October 2011. Two major earthquakes were experienced at the Tabanli and Edremit district of Van. The moment magnitudes of these earthquakes were announced as 7.2 and 5.6, respectively. The investigated school building in this study was located in the city of Van and collapsed after first major earthquake (Mw=7.2). Structural details of the load-bearing members of the investigated building including as-built drawings and specified material properties were obtained. Based on obtained data, a numerical model was created to simulate the behavior of the building under code specified earthquake effects. Earthquake performance assessment of the structure was carried based on the recommendations given in the related chapter of the Turkish Seismic Code. Pushover analyses were performed and expected member by member damage levels and overall structural damage were determined in accordance with Turkish Seismic Code. The results are discussed to enlighten the actual cause of the collapse.

scholarly journals Analysis of the Actual Contact Surface of Selected Aircraft Tires with the Airport Pavement as a Function of Pressure and Vertical Load

Coatings ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 591
Author(s):  
Mariusz Wesołowski ◽  
Krzysztof Blacha ◽  
Paweł Pietruszewski ◽  
Paweł Iwanowski
Keyword(s):  
Contact Area ◽  
Contact Surface ◽  
Load Capacity ◽  
Surface Friction ◽  
Vertical Load ◽  
Tire Pressure ◽  
Wheel Load ◽  
Friction Tester ◽  
Flight Operations ◽  
Research Studies

The contact surface of the wheel with the airport surface is important for the safety of flight operations in the ground manoeuvring area. The area of the contact surface, its shape and stress distribution at the pavement surface are the subject of many scientists’ considerations. However, there are only a few research studies which include pressure and vertical load directly and its influence on tire-pavement contact area. There are no research studies which take into account aircraft tires. This work is a piece of an extensive research project which aims to develop a device and a method for continuous measurement of the natural airport pavement’s load capacity. One of the work elements was to estimate the relationship between wheel pressure and wheel pressure on the surface, and the area of the contact surface. The results of the research are presented in this article. Global experience in this field is cited at the beginning of the article. Then, the theoretical basis for calculating the wheel with the road surface contact area was presented. Next, the author’s research views and measurement method are presented. Finally, the obtained test results and comments are shown. The tests were carried out for four types of tires. Two of them were airplane tires from the PZL M28 Skytruck/Bryza and Sukhoi Su-22 aircraft. Two more came from the airport ASFT (airport surface friction tester) friction tester-one smooth ASTM; the other smooth retreaded type T520. The tires were tested in a pressure range from 200 to 800 kPa. The range of vertical wheel load on the pavement was 3.23–25.93 kN for airplane tires, and 0.8–4.0 kN for friction tester tires. The tests proved a significant influence of the wheel pressure value and wheel pressure on the surface on the obtained contact surface area of the wheel with the surface. In addition, it was noted that the final shape and size of the contact surface is affected by factors other than wheel pressure, tire pressure and dimensions.

scholarly journals Seismic Vulnerability and Property Losses to the Portuguese Industrial Steel Building Stock

2018 ◽  
Vol 2 (3) ◽  
pp. 40-52
Author(s):  
Miguel Araújo ◽  
José Miguel Castro ◽  
Mário Marques
Keyword(s):  
Seismic Vulnerability ◽  
Production Equipment ◽  
Industrial Building ◽  
Economic Resilience ◽  
Building Stock ◽  
Industrial Property ◽  
Mainland Portugal ◽  
Industrial Buildings ◽  
Steel Building ◽  
Property Losses

Industry plays a key role in the economy of a country, people welfare and socio-economic resilience to natural disasters. Earthquakes are known to have damaging impacts on industrial property and activity, oftentimes resulting in costly structural and non-structural losses to industrial buildings, business closure, production failure and job losses. Notwithstanding this fact, the industrial building stock has been continuously excluded from seismic risk models developed for Portugal as it is usually assumed that industrial buildings are expected to withstand strong earthquakes due to their lightweight and design governed by wind loads. The aim of this paper is thus to give a first contribution to the assessment of the seismic vulnerability and property losses of the existing Portuguese industrial steel building stock. Both losses to structural and non-structural components and industry-specific contents, such as production equipment and machinery, are taken into account. The expected direct industrial property losses for a probability of exceedance of 10 % in 50 years for mainland Portugal are herein estimated.

scholarly journals Study on Optimization Seismic Design of Tall Building Structure

2015 ◽  
Vol 4 (2) ◽  
pp. 17
Author(s):  
Lei Yang
Keyword(s):  
Seismic Design ◽  
Optimization Design ◽  
Engineering Practice ◽  
Building Structure ◽  
Design Code ◽  
Stage Design ◽  
High Rise ◽  
Seismic Design Code ◽  
Earthquake Performance ◽  
Property Losses

<p>The heavy casualties and property losses caused by the earthquake this huge disaster, making high-rise building seismic become the focus of attention. Our new building seismic design code (GB50011-2001) (hereinafter referred to as "Seismic Design Code”) continue to be used (GBJ-89) specification to determine the "three earthquake performance objectives, two-stage design step" seismic design, and made many important supplement and perfect. The new seismic design of buildings in terms of requirements for introducing means as constraints optimization design, optimization design closer to engineering practice.</p>

scholarly journals The Behavior of a Thread-Bar Grouted Anchor in Soils from Local Strain Monitoring

2020 ◽  
Vol 10 (20) ◽  
pp. 7194
Author(s):  
Paolo Ruggeri ◽  
Viviene M. E. Fruzzetti ◽  
Giuseppe Scarpelli
Keyword(s):  
Shear Strength ◽  
Load Capacity ◽  
Poor Performance ◽  
Local Strain ◽  
International Standards ◽  
Strain Gauges ◽  
Fixed Length ◽  
Strain Monitoring ◽  
Sand Deposit ◽  
Low Shear

International standards discourage the use of grouted anchors with a fixed length exceeding 10 m. However, grouted anchors with a fixed length between 10 and 20 m are frequently used in Italy to transfer high loads to ground with poor geotechnical properties. This paper presents the results of investigation tests on an anchor with a length of 36 m, of which 18 m is fixed, sloping 40° from the horizontal; the anchor is comprised of a reinforced thread-bar which was instrumented with strain gauges and founded in nonhomogeneous ground, a sand deposit followed by marly clay. The test aimed at investigating the progressive mobilization of the shear strength along the foundation. The results indicate a very low shear strength offered by the sand, probably disturbed by the drilling, and an unusually fast mobilization of the shear strength in the marly clay at the deep end of the anchor. The results are particularly useful to identify the reasons for the observed poor performance of the grouted anchor. In particular, the study once again made it clear how important the influence of the execution details on reaching the expected load capacity may be, and likewise the practice of investigation tests on suitably instrumented test anchors.

An International Comparison of Production Techniques : the Coal-Fired Electricity Generating Industry

1966 ◽  
Vol 36 ◽  
pp. 30-42
Keyword(s):  
Economic Growth ◽  
International Comparison ◽  
Technological Progress ◽  
Empirical Investigation ◽  
Poor Performance ◽  
Production Techniques

There is a widely held view that Britain's poor performance in exports and economic growth can be attributed to relatively old-fashioned techniques of production—a handicap which might be particularly important in industries where technological progress is rapid. The only way to establish whether this view is right or not is by empirical investigation. Unfortunately such investigation is difficult, because not many industries have adequate statistics.

DRIFT DEMANDS OF LOW-DUCTILE MOMENT RESISTANCE FRAMES (MRF) UNDER FAR FIELD EARTHQUAKE EXCITATIONS

2016 ◽  
Vol 78 (6) ◽  
Author(s):  
Mohammadreza Vafaei ◽  
Sophia C. Alih ◽  
Qotrunnada Abdul Rahman
Keyword(s):  
Structural Damage ◽  
Load Capacity ◽  
Time History ◽  
Seismic Excitation ◽  
Nonlinear Time History Analysis ◽  
Soft Story ◽  
History Analysis ◽  
The Stability ◽  
Nonlinear Time History ◽  
Strong Ground

Most of current Malaysian’s structures have not been designed with consideration of seismic excitation effect. Tremors that have been recorded locally due to active local faults and earthquake events in neighboring countries have raised the question about the level of safety of these structures.  The effects of seismic excitation on the stability and fragility of the structures are now being concerned by most researchers and engineers in order to mitigate structural damage and societal losses. This study focuses on the seismic performance of Reinforced Concrete (RC) Moment Resistance Frames (MRF) in Malaysia which has been only designed to resist gravity and wind loads effects. An ordinary building layout with different number of stories (four, seven, and 10 stories) is selected in a way that can represent the potential of soft-story phenomenon in RC buildings in Malaysia. Such structures have limited lateral load capacity to withstand against strong ground motion. Nonlinear time history analysis is used to analyze the structures using seven different ground motions scaled to 0.05g, 0.1g and 0.15g to suit Malaysian condition. The outcomes of this study illustrate the vulnerability of the typical RC, MRF structures in Malaysia to soft-story phenomenon and clarify on the necessity of seismic retrofit for such structures.  

Structural performance of buildings during the 30 November 2018 M7.1 Anchorage, Alaska earthquake

2021 ◽  
pp. 875529302110435
Author(s):  
Wael M Hassan ◽  
Janise Rodgers ◽  
Christopher Motter ◽  
John Thornley
Keyword(s):  
Structural Damage ◽  
Seismic Vulnerability ◽  
The United States ◽  
Structural Performance ◽  
Single Family ◽  
Steel Buildings ◽  
Test Bed ◽  
Building Stock ◽  
Ground Acceleration ◽  
Nonstructural Components

Southcentral Alaska, the most populous region in Alaska, was violently shaken by a Mw 7.1 earthquake on 30 November 2018 at 8:29 am Alaska Standard Time. This was the largest magnitude earthquake in the United States close to a population center in over 50 years. The earthquake was 46 km deep, and the epicenter was 12 km north of Anchorage and 19 km west of Eagle River. The event affected some 400,000 residents, causing widespread damage in highways, nonstructural components, non-engineered and older buildings, and structures on poorly compacted fills. A few isolated serious injuries and partial collapses took place. Minor structural damage to code-conforming buildings was observed. A significant percentage of the structural damage was due to geotechnical failures. Building stock diversity allows use of the region as a large test bed to observe how local building practices affected earthquake damage levels. The prevailing peak ground acceleration (PGA) was 0.2–0.32 g, causing shaking intensity at most sites of 50%–60% of the ASCE 7-16 design basis earthquake acceleration. Thus, the seismic vulnerability of building stock in the region was not truly tested. Reinforced concrete buildings had minor structural damage, except in a few cases of shear wall and transfer girder shear cracking. Fiber-reinforced polymer (FRP)-retrofitted buildings performed satisfactorily. Concrete-masonry-unit (CMU) masonry buildings experienced serious structural damage in many cases, including relatively newer buildings. The earthquake caused widespread structural damage in non-engineered buildings (primarily wood and CMU masonry) that exist widely in the region, especially in Eagle River. Of these, non-engineered single-family wood buildings had the heaviest structural damage. No structural damage could be observed in steel buildings. The aftershock sequence, which included 7 M5+ and 50 M4+ events, exacerbated structural damage in all types of buildings. The present study is based on the EERI field reconnaissance mission conducted by the authors following the earthquake. Based on the observed damage and structural performance, seismic risk mitigation recommendations are suggested.

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