• Title/Summary/Keyword: static studies

Search Result 927, Processing Time 0.026 seconds

Estimation of impact characteristics of RC slabs under sudden loading

  • Erdem, R. Tugrul
    • Computers and Concrete
    • /
    • v.28 no.5
    • /
    • pp.479-486
    • /
    • 2021
  • Reinforced concrete (RC) slabs are exposed to several static and dynamic effects during their period of service. Accordingly, there are many studies focused on the behavior of RC slabs under these effects in the literature. However, impact loading which can be more effective than other loads is not considered in the design phase of RC slabs. This study aims to investigate the dynamic behavior of two-way RC slabs under sudden impact loading. For this purpose, 3 different simply supported slab specimens are manufactured. These specimens are tested under impact loading by using the drop test setup and necessary measurement devices such as accelerometers, dynamic load cell, LVDT and data-logger. Mass and drop height of the hammer are taken constant during experimental study. It is seen that rigidity of the specimens effect experimental results. While acceleration values increase, displacement values decrease as the sizes of the specimens have bigger values. In the numerical part of the study, artificial neural networks (ANN) analysis is utilized. ANN analysis is used to model different physical dynamic processes depending upon the experimental variables. Maximum acceleration and displacement values are predicted by ANN analysis. Experimental and numerical values are compared and it is found out that proposed ANN model has yielded consistent results in the estimation of experimental values of the test specimens.

Comprehensive evaluating the stability of slope reinforced with free and fixed head piles

  • Xixi Xiong;Ying Fan;Jinzhe Wang;Pooya Heydari
    • Geomechanics and Engineering
    • /
    • v.32 no.5
    • /
    • pp.523-540
    • /
    • 2023
  • The failure of slope can cause remarkable damage to either human life or infrastructures. Stabilizing piles are widely utilized to reinforce slope as a slip-resistance structure. The workability of pile-stabilized slopes is affected by various parameters. In this study, the performance of earth slope reinforced with piles and the behavior of piles under static load, by shear reduction strength method using the finite difference software (FLAC3D) has been investigated. Parametric studies were conducted to investigate the role of pile length (L), different pile distances from each other (S/D), pile head conditions (free and fixed head condition), the effect of sand density (loose, medium, and high-density soil) on the pile behavior, and the performance of pile-stabilized slopes. The performance of the stabilized slopes was analyzed by evaluating the factor of safety, lateral displacement and bending moment of piles, and critical slip mechanism. The results depict that as L increased and S/D reduced, the performance of slopes stabilized with pile gets better by raising the soil density. The greater the amount of bending moment at the shallow depths of the pile in the fixed pile head indicates the effect of the inertial force due to the structure on the pile performance.

3D stability of pile stabilized stepped slopes considering seismic and surcharge loads

  • Long Wang;Meijuan Xu;Wei Hu;Zehang Qian;Qiujing Pan
    • Geomechanics and Engineering
    • /
    • v.32 no.6
    • /
    • pp.639-652
    • /
    • 2023
  • Stepped earth slopes incorporated with anti-slide piles are widely utilized in landslide disaster preventions. Explicit consideration of the three-dimensional (3D) effect in the slope design warrants producing more realistic solutions. A 3D limit analysis of the stability of pile stabilized stepped slopes is performed in light of the kinematic limit analysis theorem. The influences of seismic excitation and surcharge load are both considered from a kinematic perspective. The upper bound solution to the factor of safety is optimized and compared with published solutions, demonstrating the capability and applicability of the proposed method. Comparative studies are performed with respect to the roles of 3D effect, pile location, pile spacing, seismic and surcharge loads in the safety assessments of stepped slopes. The results demonstrate that the stability of pile reinforced stepped slopes differ with that of single stage slopes dramatically. The optimum pile location lies in the upper portion of the slope around Lx/L = 0.9, but may also lies in the shoulder of the bench. The pile reinforcement reaches 10% universally for a looser pile spacing Dc/dp = 5.0, and approaches 70% when the pile spacing reaches Dc/dp = 2.0.

A Direct Utility Model with Dynamic Constraint

  • Kim, Byungyeon;Satomura, Takuya;Kim, Jaehwan
    • Asia Marketing Journal
    • /
    • v.18 no.4
    • /
    • pp.125-138
    • /
    • 2017
  • The goal of the study is to understand how consumers' constraint as opposed to utility structure gives rise to final decision when consumers purchase more than one variant of product at a time, i.e., horizontal variety seeking or multiple-discreteness. Purchase and consumption decision not only produces utility but also involves some sort of cognitive pressure. Past consumption or last purchase is likely to be linked to this burden we face such as concern for obesity, risk of harm, and guilt for mischief. In this research, the existence and the role of dynamic constraint are investigated through a microeconomic utility model with multiple dynamic constraint. The model is applied to the salty snacks data collected from field study where burden for spiciness serves as a constraint. The results are compared to the conventional multiple discreteness choice models of static constraints, and policy implications on price discounts is explored. The major findings are that first, one would underestimate the level of consumer preference for product offerings when ignoring the carry-over of the concern from the past consumption, and second, the impact of price promotion on demand would be properly evaluated when the model allows for the role of constraint as both multiple and dynamic. The current study is different from the existing studies in two ways. First, it captures the effect of 'mental constraint' on demand in formal economic model. Second, unlike the state dependence well documented in the literature, the study proposes the notion of state dependence in different way, via constraint rather than utility.

Analysis of Gear Noise and Design for Gear Noise Reduction (저소음 치차설계를 위한 치형수정에 관한 연구)

  • Yoon, Koo-Young;Park, Wang-Jun
    • Journal of the Korean Society for Precision Engineering
    • /
    • v.13 no.4
    • /
    • pp.129-135
    • /
    • 1996
  • The area of gear vibration and noise, has recently been the focus of many studies. The proper kinematic and geometric design of gears, the mathematical modeling of gear system are essential for a good design. This work present a gear disign for reducing noise, and practical approaches used for machinery noise reduction slong with the summary of methods available for predicting gear noise in terms of the transmis- sion error, and show a comparative study with other methods. A new tooth profile modification is proposed for reducing vibration and noise of involute gears. The method is based on the use of cubic spline curves. The tooth profile is constrained to assume an involute shape during the loaded operation. Thus the new gear profile assures conjugate motion at all points along the line of action. The new profile is found to result in a more uniform static transmission error compared to not only standard involute profile but also modificated profile therby contributing to the improvement of vibration and noise characteristics of the gear.

  • PDF

Hydrophobicity Evaluation of Oblique Micro-asperities Structures (경사 돌기 표면의 젖음 특성 평가)

  • Sung Ik Beak;Tae Wan Kim
    • Tribology and Lubricants
    • /
    • v.39 no.2
    • /
    • pp.56-60
    • /
    • 2023
  • In this study, we evaluate the anisotropic flow of droplets according to the directionality of asperities. We manufacture a mold with an inclined hole by adjusting the jig angle using a high-power diode laser. Using the manufactured mold, we prepare specimens for wettability studies by the micro molding technique. We fabricate twelve kinds of surfaces with micro-asperities inclined at 0°, 15°, 30°, and 45° for asperity pitches of 100 ㎛, 200 ㎛, and 300 ㎛. We evaluate the static and dynamic behaviors of the droplets as a function of the asperities pitch and inclination angles. The anisotropic effect increases as the pitch increases between asperities, and the anisotropic flow characteristics increase as the inclination angle of the asperities increases. On the surface with hole pitches of 100 ㎛ and 200 ㎛, the contact angle of the droplet shows high hydrophobicity at approximately 160°, but on the surface with the 300-㎛ hole pitch, the contact angle is approximately 110°, indicating that the hydrophobic effect rapidly reduces. Additionally, when the inclination angle of the asperities is approximately 30°, the left and right contact angle deviations of the droplet are the lowest, showing that the roll-off angle is relatively low.

Assessment of seismic retrofitting for soft-story buildings using gapped inclined brace system

  • Tohamy, Mohamed. A.;Elsayed, Mostafa. M.;Akl, Adel. Y.
    • Earthquakes and Structures
    • /
    • v.22 no.3
    • /
    • pp.319-330
    • /
    • 2022
  • Retrofit of soft-story buildings due to seismic loads using Gap-Inclined-Brace (GIB) system is considered a new retrofit technique that aims to maintain both strength and stiffness of structure. In addition, it provides more ductility and less P-delta effect, and subsequently better performance is observed. In this paper, the effect of the eccentricity between GIB and the retrofitted column due to installation on the efficiency of the retrofitting system is studied. In addition, a modification in the determination method of GIB properties is introduced to reduce the eccentricity effect. Also, the effect of GIB system on the seismic response of mid-rise buildings with different heights considering soft-story at various heights has been studied. A numerical model is developed to study the impact of such system on the response of retrofitted soft-story buildings under the action of seismic loads. To achieve that goal, this model is used to perform a numerical investigation, by considering five case study scenarios represent several locations of soft-story of two mid-rise reinforced concrete buildings. At first, Non-linear static pushover analysis was carried out to develop the capacity curves for case studies. Then, Non-linear time history analyses using ten earthquake records with five peak ground accelerations is performed for each case study scenario before and after retrofitting with GIB. The results show that large GIB eccentricity reduce the ultimate lateral resistance and deformation capacity of the retrofitting system. Moreover, the higher the retrofitted building, the more deformation capacity is observed but without significant increase in ultimate lateral resistance.

Performance evaluation of plasma nitrided 316L stainless steel during long term high temperature sodium exposure

  • Akash Singh;R. Thirumurugesan;S. Krishnakumar;Revati Rani;S. Chandramouli;P. Parameswaran;R. Mythili
    • Nuclear Engineering and Technology
    • /
    • v.55 no.4
    • /
    • pp.1468-1475
    • /
    • 2023
  • Enhancement of wear resistance of components used in fast reactors is necessary for long service life of the components. Plasma nitriding is a promising surface modification technology to impart high hardness and improved wear resistance of various steel components. This study discusses the characterization of chrome nitrided SS316L casing ring used in secondary sodium pump of fast breeder reactor and its stability under long term sodium exposure. Microstructural and hardness analysis showed that stress relieved component could be chrome nitrided successfully to a thickness of about 100 ㎛. Assessment of in-sodium performance of the chrome nitrided casing ring subjected to long term exposure up to 5000h at 550℃, showed retention of chrome nitrided layer with a case depth almost similar to that before sodium exposure. A slight decrease in the hardness was observed due to prolonged high temperature sodium exposure. Tribological studies indicate very low coefficient of friction indicating the retention of good wear resistance of the coating even after long term sodium exposure.

Experimental and numerical investigations on reinforcement arrangements in RC deep beams

  • Husem, Metin;Yilmaz, Mehmet;Cosgun, Suleyman I.
    • Advances in concrete construction
    • /
    • v.13 no.3
    • /
    • pp.243-254
    • /
    • 2022
  • Reinforced concrete (RC) deep beams are critical structural elements used in offshore pile caps, rectangular cross-section water tanks, silo structures, transfer beams in high-rise buildings, and bent caps. As a result of the low shear span ratio to effective depth (a/d) in deep beams, arch action occurs, which leads to shear failure. Several studies have been carried out to improve the shear resistance of RC deep beams and avoid brittle fracture behavior in recent years. This study was performed to investigate the behavior of RC deep beams numerically and experimentally with different reinforcement arrangements. Deep beams with four different reinforcement arrangements were produced and tested under monotonic static loading in the study's scope. The horizontal and vertical shear reinforcement members were changed in the test specimens to obtain the effects of different reinforcement arrangements. However, the rebars used for tension and the vertical shear reinforcement ratio were constant. In addition, the behavior of each deep beam was obtained numerically with commercial finite element analysis (FEA) software ABAQUS, and the findings were compared with the experimental results. The results showed that the reinforcements placed diagonally significantly increased the load-carrying and energy absorption capacities of RC deep beams. Moreover, an apparent plastic plateau was seen in the load-displacement curves of these test specimens in question (DE-2 and DE-3). This finding also indicated that diagonally located reinforcements improve displacement ductility. Also, the numerical results showed that the FEM method could be used to accurately predict RC deep beams'behavior with different reinforcement arrangements.

The Impact of Competition on the Profitability and Risk-Taking of Commercial Banks in India

  • RASTOGI, Shailesh;KANOUJIYA, Jagjeevan;BHIMAVARAPU, Venkata Mrudula;GAUTAM, Rahul Singh
    • The Journal of Asian Finance, Economics and Business
    • /
    • v.9 no.5
    • /
    • pp.377-388
    • /
    • 2022
  • The purpose of this article is to investigate the impact of competition on the performance of Indian banks. The survey includes banks from both the public and private sectors. The study will collect data for four years, from 2015 to 2019. Dynamic and static panel data are applied to estimate the association between competition and the bank's performance. Profitability and risk-taking are the performance measures used in the study. The study's main findings are that competition does not impact the banks' profitability in India. However, the findings concerning risk-taking are mixed. Therefore, it can be inferred that overall competition does not impact the banks' performance in India. Other measures of performance of the banks could have been used in the study. It is a limitation to use data of four years. Data for a much more extended period could have also been used. This is one of the few papers on the subject. Therefore, its contribution is very significant. The gap in studies on the topic of competition versus performance of the banks is veritably filled by the current study's findings.