Search results for: lateral strength

Authors: Ami Nomura, Ken Imanishi, Etsuko Ueda, Tadahiro Wada, Shinichi Enoki

Abstract:

Recently, there have been a lot of earthquakes in Japan. It is necessary to promote seismic isolation devices for buildings. The devices have been hardly diffused in attached houses, because the devices are very expensive. We should develop a low-cost seismic isolation device for detached houses. We suggested a new seismic isolation device which uses a two-layer circular tube as a unit. If hysteresis is produced in the two-layer circular tube under lateral compression load, we think that the two-layer circular tube can have energy absorbing capacity. It is necessary to contact the outer layer and the inner layer to produce hysteresis. We have previously reported how the inner layer comes in contact with the outer layer from a perspective of analysis used mechanics of materials. We have clarified that the inner layer comes in contact with the outer layer under a lateral compression load. In this paper, we explored contact area between the outer layer and the inner layer under a lateral compression load by using FEA. We think that changing the inner layer’s thickness is effective in increase the contact area. In order to change the inner layer’s thickness, we changed the shape of the inner layer. As a result, the contact area changes depending on the inner layer’s thickness. Additionally, we experimented to check whether hysteresis occurs in fact. As a consequence, we can reveal hysteresis in the two-layer circular tube under the condition.

Keywords: contact area, energy absorbing capacity, hysteresis, seismic isolation device

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Authors: Soner Guler, Demet Yavuz, Fuat Korkut

Abstract:

Synthetic fibers are commonly used in many civil engineering applications because of its some superior characteristics such as non-corrosive and cheapness. This study presents the results of experimental study on compressive strength of synthetic fiber reinforced concretes. Two types of polyamide (PA) synthetic fiber with the length of 12 and 54 mm are used for this study. The fiber volume ratio is kept as 0.25%, 0.75%, and 0.75% in all mixes. The plain concrete compressive strength is 36.2 MPa. The test results clearly show that the increase in compressive strength for synthetic fiber reinforced concretes is significant. The greatest increase in compressive strength is 23% for PA synthetic fiber reinforced concretes with 0.75% fiber volume.

Keywords: synthetic fibers, polyamide fibers, fiber volume, compressive strength

Procedia PDF Downloads 502

Authors: Mohammad Jan-Nataj Zeinab, Kahrizi Sedighe, Bayat Noshin, Giti Torkaman

Abstract:

According to the importance of the back extensor muscle strength in postmenopausal women, this study aimed to determine the relationship between strength and changes in the thickness of back extensor muscles during isometric contraction in healthy and osteoporotic postmenopausal women. Strength and thickness of the muscles of 42 postmenopausal women were measured respectively, using a handheld dynamometer and ultrasonography. Also, the Pearson correlation coefficient was used to analyze the relationship between the strength and thickness. The results indicated a high reproducibility dynamometer test and ultrasonography. The decrease of strength in people with osteoporosis, occurred more through changes in muscle structure such as reducing the number and size of muscle fibers than changes in the nervous system part.

Keywords: back extensor muscles, strength, thickness, osteoporosis

Procedia PDF Downloads 242

Authors: Vinci Mojamdar, Govind S. Gupta

Abstract:

Moving beds in the presence of gas flow are widely used in metallurgical and chemical industries like blast furnaces, catalyst reforming, drying, etc. Pressure drop studies in co- and counter – current conditions have been done by a few researchers. However, to the best of authours knowledge, proper pressure drop study with lateral gas injection lacks especially in the presence of cavity and nozzle protrusion inside the packed bed. The latter study is more useful for metallurgical industries for the processes such as blast furnaces, shaft reduction and, COREX. In this experimental work, a two dimensional cold model with slot type nozzle for lateral gas injection along with the plastic beads as packing material and dry air as gas have been used. The variation of pressure drop is recorded at various horizontal and vertical directions in the presence of cavity and nozzle protrusion. The study has been performed in both moving and stationary beds. Also, the experiments have been carried out in both increasing as well as decreasing gas flow conditions. Experiments have been performed at various gas flow rates and packed bed heights. Some interesting results have been reported such as there is no pressure variation in the moving bed for both the increasing and decreasing gas flow condition that is different from the stationary bed. Pressure hysteresis loop has been observed in a stationary bed.

Keywords: lateral gas injection, moving bed, pressure drop, pressure hysteresis, stationary bed

Procedia PDF Downloads 285

Authors: Enrique Bazan-Zurita, Sittipong Jarernprasert, Jacobo Bielak

Abstract:

We study the effects of soil-structure interaction (SSI) on the inelastic seismic response of a single-degree-of-freedom system whose hysteretic behaviour exhibits stiffness and/or strength degrading characteristics. Two sets of accelerograms are used as seismic input: the first comprising 87 record from stiff to medium stiff sites in California, and the second comprising 66 records from the soft lakebed of Mexico City. This study focuses in three seismic response parameters: ductility demand, inter-story drift, and total lateral displacement. The results allow quantitative estimates of changes in such parameters in an SSI system in comparison with those corresponding to the associated fixed-base system. We found that degrading features affect significantly both the response of fixed-base structures and the impact of soil-structure interaction. We propose a procedure to incorporate the results of this and similar studies in seismic design regulations for SSI system with anticipated nonlinear degrading behaviour.

Keywords: inelastic, seismic, building, foundation, interaction

Procedia PDF Downloads 268

Authors: T. Hirata, M. G. Silva, L. M. Rosa

Abstract:

The balance ability during task kick in soccer is a determining factor in the execution of functional movements that require a high-performance motor coordination. The current experiment explored it during an instep soccer kick and functional task kicking. Their kicking performance was measured in terms of the sway characteristics using lateral and antero-posterior balance of the center of pressure (COP) for the supporting leg and the kinematic data, the supporting leg’s knee angle. The motion was realized with one-legged stance of five male indoor soccer players and using the trigger device ball controller. The results showed large balance in antero-posterior direction than in lateral direction. However, each player adopts a different way to kick the ball, and the media-lateral displacement of the COP showed no correlation with the balance skill.

Keywords: kicking performance, center of pressure, one-legged stance, balance ability

Procedia PDF Downloads 603

Authors: Ami Nomura, Ken Imanishi, Yukinori Taniguchi, Etsuko Ueda, Tadahiro Wada, Shinichi Enoki

Abstract:

Recently, there have been a lot of earthquakes in Japan. It is necessary to promote seismic isolation devices for buildings. The devices have been hardly diffused in attached houses, because the devices are very expensive. We should develop a low-cost seismic isolation device for detached houses. We suggested a new seismic isolation device which uses a two-layer circular tube as a unit. If hysteresis is produced in the two-layer circular tube under lateral compression load, we think that the two-layer circular tube can have energy absorbing capacity. It is necessary to contact the outer layer and the inner layer to produce hysteresis. We have previously reported how the inner layer comes in contact with the outer layer from a perspective of analysis used mechanics of materials. We have clarified that the inner layer comes in contact with the outer layer under a lateral compression load. In this paper, we explored contact area between the outer layer and the inner layer under a lateral compression load by using FEA. We think that changing the inner layer’s thickness is effective in increase the contact area. In order to change the inner layer’s thickness, we changed the shape of the inner layer. As a result, the contact area changes depending on the inner layer’s thickness. Additionally, we experimented to check whether hysteresis occurs in fact. As a consequence, we can reveal hysteresis in the two-layer circular tube under the condition.

Keywords: contact area, energy absorbing capacity, hysteresis, seismic isolation device

Procedia PDF Downloads 342

Authors: Ulli Heinlein, Thomas Freimann

Abstract:

Pre-applied bonded membranes are used as positive-side waterproofing on concrete basements, are installed before the concrete work, and achieve a tear-resistant and waterproof bond with the subsequently placed fresh concrete. This bond increases redundancy compared to lose waterproofing membranes by preventing lateral water migrations in the event of damage. So far, the membranes have been tested in the laboratory, but it is not yet known how they behave on construction sites in the presence of dirt, soil, cement paste or moisture. This article, therefore, conducts investigations on six construction sites using 18 test slabs where the pre-applied bonded membranes are selectively contaminated or wetted. Subsequently, cores are taken, and the influence of the contaminations on the adhesive tensile strength and waterproof bond is tested. Pre-applied bonded membranes with smooth or granular but closed surfaces show no sensitivity to wetness, whereas open-pored membranes with nonwovens do not tolerate standing water. Contaminations decline the performance of all pre-applied bonded membranes since a separating layer is formed between the bonding layer and the concrete. The influence depends on the thickness of the contamination and its mechanical properties.

Keywords: waterproofing, positive-side waterproofing, basement, pre-applied bonded waterproofing membrane, In-situ testing, lateral water migrations

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Authors: Ahmed A.D. Sarhan, Chong Feng Duan, Mum Wai Yip, M. Sayuti

Abstract:

Rapid Prototyping (RP) technologies enable physical parts to be produced from various materials without depending on the conventional tooling. Fused Deposition Modeling (FDM) is one of the famous RP processes used at present. Tensile strength and compressive strength resistance will be identified for different sample structures and different layer orientations of ABS rapid prototype solid models. The samples will be fabricated by a FDM rapid prototyping machine in different layer orientations with variations in internal geometrical structure. The 0° orientation where layers were deposited along the length of the samples displayed superior strength and impact resistance over all the other orientations. The anisotropic properties were probably caused by weak interlayer bonding and interlayer porosity.

Keywords: building orientation, compression strength, rapid prototyping, tensile strength

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Authors: E. Mello, C. Ribellato, E. Mohamedelhassan

Abstract:

This study investigated the improvement in concrete properties with addition of cellulose, steel, carbon and PET fibers. Each fiber was added at four percentages to the fresh concrete, which was moist-cured for 28-days and then tested for compressive, flexural and tensile strengths. Changes in strength and increases in cost were analyzed. Results showed that addition of cellulose caused a decrease between 9.8% and 16.4% in compressive strength. This range may be acceptable as cellulose fibers can significantly increase the concrete resistance to fire, and freezing and thawing cycles. Addition of steel fibers to concrete increased the compressive strength by up to 20%. Increases 121.5% and 80.7% were reported in tensile and flexural strengths respectively. Carbon fibers increased flexural and tensile strengths by up to 11% and 45%, respectively. Concrete strength properties decreased after the addition of PET fibers. Results showed that improvement in strength after addition of steel and carbon fibers may justify the extra cost of fibers.

Keywords: concrete, compressive strength, fibers, flexural strength, tensile strength

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Authors: Ghada Diaa, Enas A. Khattab

Abstract:

Ultra High Strength Concrete (UHSC) is a new advanced concrete that is being transferred from laboratory researches to practicable applications. In addition to its excellent durability properties, UHSC has high compressive and tensile strengths, and high modulus of elasticity. Despite of this low degree of hydration, ultra high strength values can be achieved by controlling the mixture proportions. In this research, an experimental program was carried out to investigate the shear behavior of ultra high strength concrete beams. A total of nine beams were tested to determine the effect of different parameters on the shear behavior of UHSC beams. The parameters include concrete strength, steel fiber volume, shear span to depth ratio, and web reinforcement ratio. The results demonstrated that nominal shear stress at cracking load and at ultimate load increased with the increase of concrete strength or the decrease in shear span-depth ratio. Using steel fibers or shear reinforcement increases the ultimate shear strength and makes the shear behavior more ductile. In this study, a simplified analytical model to calculate the shear strength of UHSC beams is introduced. Shear strength estimated according to the proposed method in this research is in good agreement with the experimental results.

Keywords: ultra high strength, shear strength, diagonal, cracking, steel fibers

Procedia PDF Downloads 598

Authors: H. Ahmad Raji, R. Ziaie Moayed, M. A. Nozari

Abstract:

Xanthan gum (XG) an eco-friendly biopolymer has been recently explicitly investigated for ground improvement approaches. Rheological behavior of this additive strongly depends on electrochemical condition such as pH, ionic strength and also its content in aqueous solution. So, the effects of these factors have been studied in this paper considering various XG contents as 0.25, 0.5, 1, and 2% of water. Moreover, adjusting pH values such as 3, 5, 7 and 9 in addition to increasing ionic strength to 0.1 and 0.2 in the molar scale has covered a practical range of electrochemical condition. The viscosity of grouts shows an apparent upward trend with an increase in ionic strength and XG content. Also, pH affects the polymerization as much as other parameters. As a result, XG behavior is severely influenced by electrochemical settings

Keywords: electrochemical condition, ionic strength, viscosity, xhanthan gum

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Authors: Junkyeong Kim, Seunghee Park, Ju-Won Kim, Myung-Sug Cho

Abstract:

Recently, demands for the construction of Nuclear Power Plants (NPP) using high strength concrete (HSC) has been increased. However, HSC might be susceptible to brittle fracture if the curing process is inadequate. To prevent unexpected collapse during and after the construction of HSC structures, it is essential to confirm the strength development of HSC during the curing process. However, several traditional strength-measuring methods are not effective and practical. In this study, a novel method to estimate the strength development of HSC based on electromechanical impedance (EMI) measurements using an embedded piezoelectric sensor is proposed. The EMI of NPP concrete specimen was tracked to monitor the strength development. In addition, cross-correlation coefficient was applied in sequence to examine the trend of the impedance variations more quantitatively. The results confirmed that the proposed technique can be applied successfully monitoring of the strength development during the curing process of HSC structures.

Keywords: concrete curing, embedded piezoelectric sensor, high strength concrete, nuclear power plant, self-sensing impedance

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Authors: S. Abbsi, M. R. Hadian, M. Abdolvahab, M. Jalili, S. Khafri

Abstract:

Background: According to physical effects of cardiovascular accident (CVA) which is the most common disabilities in adulthood. It seems attention to treatment and rehabilitation of this patient has importance. Hemiplegic patients have been experienced of wild functional disabilities. Numerous patients have been suffered from upper limb disabilities. Aim of this study correlation of pinch and grip strength with dexterity in adult hemiplegic. Methods: 34 adult hemiplegic in range of 50-70 years participate in this study. After introduce and take a satisfaction patient, pinch and grip strength have evaluated by dynamometer and dexterity have evaluated by Minnesota manual dexterity test and correlation effects of them have studied. Result: According to result of present investigation, patients with hemiplegia have shown significant correlation between dexterity with pinch and grip strength. Conclusion: Dexterity has correlation with pinch and grip strength, but it seems, not have correlation with age and duration of CVA.

Keywords: pinch strength, grip strength, dexterity, hemiplegia

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Authors: O. Zarrin, M. Ramezan Shirazi

Abstract:

The quality of concrete is usually defined by compressive strength, but flexural strength is the most important characteristic of concrete in a pavement which control the mix design of concrete instead of compressive strength. Therefore, the aggregates which are selected for the pavements are affected by higher flexural strength. Roller Compacting Concrete Pavement (RCCP) is not a new construction method. The other characteristic of this method is no bleeding and less shrinkage due to the lower amount of water. For this purpose, a roller is needed for placing and compacting. The surface of RCCP is not smooth; therefore, the most common use of this pavement is in an industrial zone with slower traffic speed which requires durable and tough pavement. For preparing a smoother surface, it can be achieved by asphalt paver. RCCP decrease the finishing cost because there are no bars, formwork, and the lesser labor need for placing the concrete. In this paper, different aspect of RCCP such as mix design, flexural, compressive strength and focus on the different part of RCCP on detail have been investigated.

Keywords: flexural strength, compressive strength, pavement, asphalt

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Authors: Mantai Chen, Johnny Ching Ming Ho

Abstract:

The stress-strain relationship of concrete under flexure is one of the essential parameters in assessing ultimate flexural strength capacity of RC beams. Currently, the concrete stress-strain curve in flexure is obtained by incorporating a constant scale-down factor of 0.85 in the uniaxial stress-strain curve. However, it was revealed that strain gradient would improve the maximum concrete stress under flexure and concrete stress-strain curve is strain gradient dependent. Based on the strain-gradient-dependent concrete stress-strain curve, the investigation of the combined effects of strain gradient and concrete strength on flexural strength of RC beams was extended to high strength concrete up to 100 MPa by theoretical analysis. As an extension and application of the authors’ previous study, a new flexural strength design method incorporating the combined effects of strain gradient and concrete strength is developed. A set of equivalent rectangular concrete stress block parameters is proposed and applied to produce a series of design charts showing that the flexural strength of RC beams are improved with strain gradient effect considered.

Keywords: beams, equivalent concrete stress block, flexural strength, strain gradient

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Authors: Ping-Hsiung Wang, Kuo-Chun Chang

Abstract:

There has been a common trend worldwide in the seismic design and evaluation of bridges towards the performance-based method where the lateral displacement or the displacement ductility of bridge column is regarded as an important indicator for performance assessment. However, the seismic response of a bridge to an earthquake is a combined result of cyclic displacements and accumulated energy dissipation, causing damage to the bridge, and hence the lateral displacement (ductility) alone is insufficient to tell its actual seismic performance. This study aims to propose a damage-based seismic design and evaluation method for reinforced concrete bridges on the basis of the newly developed capacity-based inelastic displacement spectra. The capacity-based inelastic displacement spectra that comprise an inelastic displacement ratio spectrum and a corresponding damage state spectrum was constructed by using a series of nonlinear time history analyses and a versatile, smooth hysteresis model. The smooth model could take into account the effects of various design parameters of RC bridge columns and correlates the column’s strength deterioration with the Park and Ang’s damage index. It was proved that the damage index not only can be used to accurately predict the onset of strength deterioration, but also can be a good indicator for assessing the actual visible damage condition of column regardless of its loading history (i.e., similar damage index corresponds to similar actual damage condition for the same designed columns subjected to very different cyclic loading protocols as well as earthquake loading), providing a better insight into the seismic performance of bridges. Besides, the computed spectra show that the inelastic displacement ratio for far-field ground motions approximately conforms to the equal displacement rule when structural period is larger than around 0.8 s, but that for near-fault ground motions departs from the rule in the whole considered spectral regions. Furthermore, the near-fault ground motions would lead to significantly greater inelastic displacement ratio and damage index than far-field ground motions and most of the practical design scenarios cannot survive the considered near-fault ground motion when the strength reduction factor of bridge is not less than 5.0. Finally, the spectrum formula is presented as a function of structural period, strength reduction factor, and various column design parameters for far-field and near-fault ground motions by means of the regression analysis of the computed spectra. And based on the developed spectrum formula, a design example of a bridge is presented to illustrate the proposed damage-based seismic design and evaluation method where the damage state of the bridge is used as the performance objective.

Keywords: damage index, far-field, near-fault, reinforced concrete bridge, seismic design and evaluation

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Authors: Ayanori Sugiyama, Takahisa Hanei, Yasuhide Higo

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Domestic demand for the construction of tunnels has been increasing in recent years in Japan. To meet this demand, various construction materials and construction methods have been developed to attain higher strength, reduction of negative impact on the environment and improvement for working conditions. In this report, we would like to introduce the newly developed shotcrete with superior hardening properties which were tested through the actual machine scale and its workability and strength development were evaluated. As a result, this new tunnel construction method was found to achieve higher workability and quicker strength development in only a couple of minutes.

Keywords: accelerator, shotcrete, tunnel, high-strength

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Authors: M. Yoneda

Abstract:

In this paper, a lateral walking design force per person is proposed and compared with Imperial College test results. Numerical simulations considering the proposed walking design force which is incorporated into the neural-oscillator model are carried out placing much emphasis on the synchronization (the lock-in phenomenon) for a pedestrian bridge model with the span length of 50 m. Numerical analyses are also conducted for an existing pedestrian suspension bridge. As compared with full scale measurements for this suspension bridge, it is confirmed that the analytical method based on the neural-oscillator model might be one of the useful ways to explain the synchronization (the lock-in phenomenon) of pedestrians being on the bridge.

Keywords: pedestrian bridge, human-induced lateral vibration, neural-oscillator, full scale measurement, dynamic response analysis

Procedia PDF Downloads 183

Authors: Muhamad Azani Yahya, Umi Nadiah Nor Ali, Mohammed Alias Yusof, Norazman Mohamad Nor, Vikneswaran Munikanan

Abstract:

In construction, concrete is one of the materials that can commonly be used as for structural elements. Concrete consists of cement, sand, aggregate and water. Concrete can be added with admixture in the wet condition to suit the design purpose such as to prolong the setting time to improve workability. For strength improvement, concrete is being added with other hybrid materials to increase strength; this is because the tensile strength of concrete is very low in comparison to the compressive strength. This paper shows the usage of a waterproofing agent in concrete to enhance the tensile strength. High tensile concrete is expensive because the concrete mix needs fiber and also high cement content to be incorporated in the mix. High tensile concrete being used for structures that are being imposed by high impact dynamic load such as blast loading that hit the structure. High tensile concrete can be defined as a concrete mix design that achieved 30%-40% tensile strength compared to its compression strength. This research evaluates the usage of a waterproofing agent in a concrete mix as an element of reinforcement to enhance the tensile strength. According to the compression and tensile test, it shows that the concrete mix with a waterproofing agent enhanced the mechanical properties of the concrete. It is also show that the composite concrete with waterproofing is a high tensile concrete; this is because of the tensile is between 30% and 40% of the compression strength. This mix is economical because it can produce high tensile concrete with low cost.

Keywords: high tensile concrete, waterproofing agent, concrete, rheology

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Authors: Lila D. Sigdel, Chin J. Leo, Samanthika Liyanapathirana, Pan Hu, Minghao Lu

Abstract:

Integral bridges are a class of bridges with integral or semi-integral abutments, designed without expansion joints in the bridge deck of the superstructure. Integral bridges are economical alternatives to conventional jointed bridges with lower maintenance costs and greater durability, thereby improving social and economic stability for the community. Integral bridges have also been proven to be effective in lowering the overall construction cost compared to the conventional type of bridges. However, there is significant uncertainty related to the design and analysis of integral bridges in response to cyclic thermal movements induced due to deck expansion and contraction. The cyclic thermal movements of the abutments increase the lateral earth pressures on the abutment and its foundation, leading to soil settlement and heaving of the backfill soil. Thus, the primary objective of this paper is to investigate the soil-abutment interaction under the cyclic translational movement of the abutment. Results from five experiments conducted to simulate different magnitudes of cyclic translational movements of abutments induced by thermal changes are presented, focusing on lateral earth pressure development at the abutment-soil interface. Test results show that the cycle number and magnitude of cyclic translational movements have significant effects on the escalation of lateral earth pressures. Experimentally observed earth pressure distributions behind the integral abutment were compared with the current design approaches, which shows that the most of the practices has under predicted the lateral earth pressure.

Keywords: integral bridge, cyclic thermal movement, lateral earth pressure, soil-structure interaction

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Authors: Z. W. Zhong, C. Xu, W. K. Choi

Abstract:

To build a thin fan-out wafer-level package, the package had to be ground to a thin level. In this work, the influence of the grinding processes on the strength of the fan-out wafer-level packages was investigated. After different grinding processes, all specimens were placed on a three-point-bending fixture installed on a universal tester for three-point-bending testing, and the strength of the fan-out wafer-level packages was measured. The experiments revealed that the average flexure strength increased with the decreasing surface roughness height of the fan-out wafer-level package tested. The grinding processes had a significant influence on the strength of the fan-out wafer-level packages investigated.

Keywords: FOWLP strength, surface roughness, three-point bending, grinding

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Authors: Orod Zarrin, Mohesn Ramezan Shirazi, Hassan Moniri

Abstract:

The use of pile foundations technique is developed to support structures and buildings on soft soil. The most important dynamic load that can affect the pile structure is earthquake vibrations. From the 1960s the comprehensive investigation of pile foundations during earthquake excitation indicate that, piles are subject to damage by affecting the superstructure integrity and serviceability. The main part of these research has been focused on the behavior of liquefiable soil and lateral spreading load on piles. During an earthquake, two types of stresses can damage the pile head, inertial load that is caused by superstructure and deformation which caused by the surrounding soil. Soil deformation and inertial load are associated with the acceleration developed in an earthquake. The acceleration amplitude at the ground surface depends on the magnitude of earthquakes, soil properties and seismic source distance. According to the investigation, the damage is between the liquefiable and non-liquefiable layers and also soft and stiff layers. This damage crushes the pile head by increasing the inertial load which is applied by the superstructure. On the other hand, the cracks on the piles due to the surrounding soil are directly related to the soil profile and causes cracks from small to large. And researchers have been listed the large cracks reason such as liquefaction, lateral spreading and inertial load. In the field of designing, elastic response of piles are always a challenge for designer in liquefaction soil, by allowing deflection at top of piles. Moreover, absence of plastic hinges in piles should be insured, because the damage in the piles is not observed directly. In this study, the performance and behavior of pile foundations during liquefaction and lateral spreading are investigated. And emphasize on the soil behavior in the liquefiable and non-liquefiable layers by different aspect of piles damage such as ranking, location and degree of damage are going to discuss.

Keywords: self-compacting concrete, fiber, tensile strength, post-cracking, direct and inverse technique

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Authors: Antanas Žiliukas, Mindaugas Kukis

Abstract:

The work deals with cellular pressure vessels subjected to internal pressure. Their cellular insert can be used for placing liquids or gases, which is necessary to carry out technological processes, and the vessel itself has a good bearing capacity. Numerical calculations of the three core structures, which measure the influence of the inner cylinder thickness on maximum bearing capacity are presented. The calculations are compared using strength criteria and they show the different strength safety level.

Keywords: pressure, strength criterion, sandwich plate, cellular vessel

Procedia PDF Downloads 290

Authors: Alfred M. Caronia

Abstract:

The aim of this pilot study was to explore an NCAA Division 1 female volleyball players’ experience of a strength and conditioning program and the result this has on self-efficacy of sport skill performance. This phenomenological study comprised of 10 college aged participants that have strength training program experience. Data was collected using semi-structured interviews and a reflective journal; the transcribed interviews were analyzed using qualitative content analysis. From the analysis, four themes emerged: performance enhancement, injury prevention, motivational experience, and learning experience. From the players’ perspective, care needs to be taken to explain the purpose of an exercise and the benefit it will have for a play performance. Other factors that play an important role in a strength training program are team motivation, individual goal setting, bonding, and communication with the strength coach, as all these items appear to be fundamentals of coaching.

Keywords: self-efficacy, skill performance, sports performance, strength training

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Authors: Jiwon Park, Jihae Hur, Kukjae Kim, Hansoo Kim

Abstract:

In this study, outriggers, which are horizontal structures connecting a building core to distant columns to increase the lateral stiffness of a tall building, are used to reduce differential axial shortening in a tall building. Therefore, the outriggers in tall buildings are used to serve the dual purposes of reducing the lateral displacement and reducing the differential axial shortening. Since the location of the outrigger greatly affects the effectiveness of the outrigger in terms of the lateral displacement at the top of the tall building and the maximum differential axial shortening, the optimum locations of the dual-purpose outriggers can be determined by an optimization method. Because the floors where the outriggers are installed are given as integer numbers, the conventional gradient-based optimization methods cannot be directly used. In this study, a piecewise quadratic interpolation method is used to resolve the integrality requirement posed by the optimum locations of the dual-purpose outriggers. The optimal solutions for the dual-purpose outriggers are searched by linear scalarization which is a popular method for multi-objective optimization problems. It was found that increasing the number of outriggers reduced the maximum lateral displacement and the maximum differential axial shortening. It was also noted that the optimum locations for reducing the lateral displacement and reducing the differential axial shortening were different. Acknowledgment: This research was supported by Basic Science Research Program through the National Research Foundation of Korea(NRF) funded by the Ministry of Science and ICT (NRF-2017R1A2B4010043) and financially supported by Korea Ministry of Land, Infrastructure and Transport(MOLIT) as U-City Master and Doctor Course Grant Program.

Keywords: concrete structure, optimization, outrigger, tall building

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Authors: Ufuk Aydın

Abstract:

The Coda attenuation and frequency dependency of seismic wave are strongly dependent on the effective stresses structures within the upper crust. In this study, the data of three different stations were used to examine the lateral variation of stress. The tectonic structures of these three areas have been examined comparatively using lateral coda tomography. In the study using the single scatter method, the window length selected to be 20 second. Coda values 80 with 94 and frequency dependency values obtained between 0.69 and 1.21. The 1/QC values for the three regions ranged from 0.0012 to 0.017, highlighting the regional differences in the seismotectonic activity of the crust. The lowest absorption values obtained from Erzurum station when the highest absorption values obtained at the Kemaliye station. The low Qc and high frequency dependency values obtained Kemaliye, which indicates that it has highest tectonic activity than other two regions. The seismo-dynamics data obtained from the study found to be in agreement with the tectonic structure of the region.

Keywords: regional coda attenuation, tectonic stress, crustal deformation

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Authors: Navid Zarif Karimi, Giangiacomo Minak, Parnian Kianfar

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Drilling is one of the most frequently used machining process for glass fiber reinforced polymer composites due to the need for structural joining. In drilling of composite laminates, interlaminar cracking, or delamination, has a detrimental effect on the compressive strength of these materials. The delamination can be controlled by adopting proper drilling condition. In this paper, the effect of feed rate, cutting speed and drill point angle on delamination and residual compressive strength of drilled GFRPs is studied. The objective is to find optimal conditions for maximum residual compressive strength.

Keywords: composite material, delamination, drilling, residual compressive strength

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Authors: Ouledja Abdessalam

Abstract:

This work Contains an experimental study of the behavior of Chlef sand under the effect of various parameters influencing on shear strength. Because of their distinct nature, sands, silts, and clays exhibit completely different behavior (shear strength, the Contracting and dilatancy, the angle of internal friction and cohesion...). By cons when these materials are mixed, their behavior will become different from each considered alone. The behavior of these mixtures (silty sands...) is currently the state of several studies to better use. We have studied in this work: The influence of the following factors on the shear strength: The density (loose and dense), the fines content (silt), The water content. The apparatus used for the tests is the casagrande shear box. This device, although one may have some disadvantages and modern instrumentation is appropriately used to study the shear strength of soils.

Keywords: shear strength, sand, silt, contractancy, dilatancy, friction angle, cohesion, fines content

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Authors: Patrícia Pires, Renata Vaz, Bárbara Teles, Marco Pato, Pedro Beckert

Abstract:

Introduction: The management of lateral third clavicle fractures can be challenging due to difficulty in distinguishing subtle variations in the fracture pattern, which may be suggestive of potential fracture instability. They occur most often in men between 30 and 50 years of age, and in individuals over 70 years of age, its distribution is equal between both men and women. These fractures account for 10%–30% of all clavicle fractures and roughly 30%–45% of all clavicle nonunion fractures. Lateral third clavicle fractures may be treated conservatively or surgically, and there is no gold standard, although the risk of nonunion or pseudoarthrosis impacts the recommendation of surgical treatment when these fractures are unstable. There are many strategies for surgical treatment, including locking plates, hook plates fixation, coracoclavicular fixation using suture anchors, devices or screws, tension band fixation with suture or wire, transacromial Kirschner wire fixation and arthroscopically assisted techniques. Whenever taking the hardware into consideration, we must not disregard that obtaining adequate lateral fixation of small fragments is a difficult task, and plates are more associated to local irritation. The aim of the appropriate treatment is to ensure fracture healing and a rapid return to preinjury activities of daily living but, as explained, definitive treatment strategies have not been established and the variety of techniques avalilable add up to the discussion of this topic. Methods and Results: We present a clinical case of a 43-year-old man with the diagnosis of a lateral third clavicle fracture (Neer IIC) in the sequence of a fall on his right shoulder after a bicycle fall. He was operated three days after the injury, and through K-wire temporary fixation and indirect reduction using a ZipTight, he underwent osteosynthesis with an interfragmentary figure-of-eight tension band with polydioxanone suture (PDS). Two weeks later, there was a good aligment. He kept the sling until 6 weeks pos-op, avoiding efforts. At 7-weeks pos-op, there was still a good aligment, starting the physiotherapy exercises. After 10 months, he had no limitation in mobility or pain and returned to work with complete recovery in strength. Conclusion: Some distal clavicle fractures may be conservatively treated, but it is widely accepted that unstable fractures require surgical treatment to obtain superior clinical outcomes. In the clinical case presented, the authors chose an osteosuture technique due to the fracture pattern, its location. Since there isn´t a consensus on the prefered fixation method, it is important for surgeons to be skilled in various techniques and decide with their patient which approach is most appropriate for them, weighting the risk-benefit of each method. For instance, with the suture technique used, there is no wire migration or breakage, and it doesn´t require a reoperation for hardware removal; there is also less tissue exposure since it requires a smaller approach in comparison to the plate fixation and avoids cuff tears like the hook plate. The good clinical outcome on this case report serves the purpose of expanding the consideration of this method has a therapeutic option.

Keywords: lateral third, clavicle, suture, fixation

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