• Title/Summary/Keyword: modified prediction of deflection

Search Result 10, Processing Time 0.017 seconds

Flexural behavior and a modified prediction of deflection of concrete beam reinforced with a ribbed GFRP bars

  • Ju, Minkwan;Park, Cheolwoo;Kim, Yongjae
    • Computers and Concrete
    • /
    • v.19 no.6
    • /
    • pp.631-639
    • /
    • 2017
  • This study experimentally investigated the flexural capacity of a concrete beam reinforced with a newly developed GFRP bar that overcomes the lower modulus of elasticity and bond strength compared to a steel bar. The GFRP bar was fabricated by thermosetting a braided pultrusion process to form the outer fiber ribs. The mechanical properties of the modulus of elasticity and bond strength were enhanced compared with those of commercial GFRP bars. In the four-point bending test results, all specimens failed according to the intended failure mode due to flexural design in compliance with ACI 440.1R-15. The effects of the reinforcement ratio and concrete compressive strength were investigated. Equations from the code were used to predict the deflection, and they overestimated the deflection compared with the experimental results. A modified model using two coefficients was developed to provide much better predictive ability, even when the effective moment of inertia was less than the theoretical $I_{cr}$. The deformability of the test beams satisfied the specified value of 4.0 in compliance with CSA S6-10. A modified effective moment of inertia with two correction factors was proposed and it could provide much better predictability in prediction even at the effective moment of inertia less than that of theoretical cracked moment of inertia.

Long-term deflection prediction in steel-concrete composite beams

  • Lou, Tiejiong;Wu, Sishun;Karavasilis, Theodore L.;Chen, Bo
    • Steel and Composite Structures
    • /
    • v.39 no.1
    • /
    • pp.21-33
    • /
    • 2021
  • This paper aims to improve the current state-of-the-art in long-term deflection prediction in steel-concrete composite beams. The efficiency of a time-dependent finite element model based on linear creep theory is verified with available experimental data. A parametric numerical study is then carried out, which focuses on the effects of concrete creep and/or shrinkage, ultimate shrinkage strain and reinforcing bars in the slab. The study shows that the long-term deformations in composite beams are dominated by concrete shrinkage and that a higher area of reinforcing bars leads to lower long-term deformations and steel stresses. The AISC model appears to overestimate the shrinkage-induced deflection. A modified ACI equation is proposed to quantify time-dependent deflections in composite beams. In particular, a modified reduction factor reflecting the influence of reinforcing bars and a coefficient reflecting the influence of ultimate shrinkage are introduced in the proposed equation. The long-term deflections predicted by this equation and the results of extensive numerical analyses are found to be in good agreement.

Model Development of Flexible Disk Grinding Process

  • Yoo, Song-Min;Choi, Myung-Jin;Kim, Young-Jin
    • Journal of Mechanical Science and Technology
    • /
    • v.14 no.10
    • /
    • pp.1114-1121
    • /
    • 2000
  • A flexible disk grinding process model was developed based on the dynamic relationship proposed by Kurfess and the influence of the major system parameters which potentially affect the grinding process was studied. Due to the process complexities, several new parameters were assumed to be kinematically dependent on the geometric layouts of the process. Different process stages had been defined depending on the kinematic relationships between the grinding disk and workpiece. A trend of depth of cut was simulated using the proposed model and compared with the empirically measured data in two dimensions. Due to a poor prediction capability of the first model, a modified model was proposed and a better performance has been proved to reveal a closer description of processed surface quality. Also a deflection length has been verified using a different analytical approach.

  • PDF

CAE Analysis of Powder Injection Molding Process for Dental Scaler Mold (치과용 스케일러 금형의 분말사출성형 CAE 해석설계)

  • Ko Y. B.;Park H. P.;Chung S. T.;Rhee B. O.;Hwang C. J.
    • Transactions of Materials Processing
    • /
    • v.14 no.6 s.78
    • /
    • pp.570-576
    • /
    • 2005
  • Powder Injection Molding(PIM) has recently been recognized as an advanced manufacturing technology for low-cost mass production of metal or ceramic parts of complicated geometry With this regards, design technology of dental scaler tip PIM mold, which has complex shape and small core pin (diameter=0.6mm), with the help of computer-aided analysis of powder injection molding process was developed. Computer-aided analysis for dental scaler tip mold was implemented by finite element method with non-Newtonian fluid, modified Cross model viscosity, PvT data of powder/binder mixture. Compter-aided analysis results, such as filling pattern, weldline formation, air vent position prediction were compared with experimental result, and eventually have been shown good agreement. The core pin (diameter=0.6mm) deflection analysis of dental scaler tip PIM mold during PIM filling process was also investigated before mold fabrication.

Flexural performance of composite sandwich wall panels with foamed concrete

  • Lei Li;Wei Huang;Zhengyi Kong;Li Zhang;Youde Wang;Quang-Viet Vu
    • Steel and Composite Structures
    • /
    • v.52 no.4
    • /
    • pp.391-403
    • /
    • 2024
  • The flexural behavior of composite sandwich wall panels with different thicknesses, numbers of holes, and hole forms, and arrangement form of longitudinal steel bar (uniform type and concealed-beam type) are investigated. A total of twelve composite sandwich wall panels are prepared, utilizing modified polystyrene particles mixed with foam concrete for the flexural performance test. The failure pattern of the composite sandwich wall panels is influenced by the extruded polystyrene panel (XPS) panel thickness and the reinforcement ratio in combination, resulting in both flexural and shear failure modes. Increasing the XPS panel thickness causes the specimens to transition from flexural failure to shear failure. An increase in the reinforcement ratio leads to the transition from flexural failure to shear failure. The hole form on the XPS panel and the steel bar arrangement form affect the loading behavior of the specimens. Plum-arrangement hole form specimens exhibit lower steel bar strain and deflection compared to linear-arrangement hole form specimens. Additionally, specimens with concealed beam-type steel bar display lower steel bar strain and deflection than uniform-type steel bar specimens. However, the hole form and steel bar arrangement form have a limited impact on the ultimate load. Theoretical formulas for cracking load are provided for both fully composite and non-composite states. When compared to the experimental values, it is observed that the cracking load of the specimens with XPS panels closely matches the calculations for the non-composite state. An accurate prediction model for the ultimate load of fully composite wall panels is developed. These findings offer valuable insights into the behavior of composite sandwich wall panels and provide a basis for predicting their performance under various design factors and conditions.

Prediction of flexural behaviour of RC beams strengthened with ultra high performance fiber reinforced concrete

  • Murthy A, Ramachandra;Aravindan, M.;Ganesh, P.
    • Structural Engineering and Mechanics
    • /
    • v.65 no.3
    • /
    • pp.315-325
    • /
    • 2018
  • This paper predicts the flexural behaviour of reinforced concrete (RC) beams strengthened with a precast strip of ultra-high performance fiber-reinforced concrete (UHPFRC). In the first phase, ultimate load capacity of preloaded and strengthened RC beams by UHPFRC was predicted by using various analytical models available in the literature. RC beams were preloaded under static loading approximately to 70%, 80% and 90% of ultimate load of control beams. The models such as modified Kaar and sectional analysis predicted the ultimate load in close agreement to the corresponding experimental observations. In the second phase, the famous fatigue life models such as Papakonstantinou model and Ferrier model were employed to predict the number of cycles to failure and the corresponding deflection. The models were used to predict the life of the (i) strengthened RC beams after subjecting them to different pre-loadings (70%, 80% and 90% of ultimate load) under static loading and (ii) strengthened RC beams after subjecting them to different preloading cycles under fatigue loading. In both the cases precast UHPFRC strip of 10 mm thickness is attached on the tension face. It is found that both the models predicted the number of cycles to failure and the corresponding deflection very close to the experimental values. It can be concluded that the models are found to be robust and reliable for cement based strengthening systems also. Further, the Wang model which is based on Palmgren-Miner's rule is employed to predict the no. of cycles to failure and it is found that the predicted values are in very good agreement with the corresponding experimental observations.

Low-velocity impact response of laminated composite plates using a higher order shear deformation theory (고차 전단 변형이론에 의한 복합재료 적층판의 저속 충격응답)

  • Lee, Young-Shin;Park, Oung
    • Transactions of the Korean Society of Mechanical Engineers
    • /
    • v.14 no.6
    • /
    • pp.1365-1381
    • /
    • 1990
  • A $C^{0}$ continuous displacement finite element method based on a higher-order shear deformation theory is employed in the prediction of the transient response of laminated composite plates subjected to low-velocity impact. A modified contact law was applied to calculate the contact force during impact. The discrete element chosen is a nine-noded quadrilateral with 5 degree-of-freedom per node. The Wilson-.theta. time integration algorithm is used for solving the time dependent equations of the impactor and the central difference method was adopted to perform time integration of the plate. Numerical results, including the contact force history, deflection, and velocity history, are presented. Comparisons of numerical results using a higher order theory and a first-order theory show that using a higher order theory provides more accurate results. Effects of boundary condition, impact velocity, and mass of the impactors are also discussed.d.

A Study on the Life Prediction and Quality Improvement of Joint in IC Package (플라스틱 IC 패키지 접합부의 수명예측 및 품질향상에 관한 연구)

  • 신영의;김종민
    • Journal of Welding and Joining
    • /
    • v.17 no.1
    • /
    • pp.124-132
    • /
    • 1999
  • Thermal fatigue strength of the solder joints is the most critical issue for TSOP(Thin Small Outline Package) because the leads of this package are extremely short and thermal deformation cannot be absorbed by the deflection of the lead. And the TSOP body can be subject to early fatigue failures in thermal cycle environments. This paper was discussed distribution of thermal stresses at near the joint between silicon chip and die pad and investigated their reliability of solder joints of TSOP with 42 alloy clad lead frame on printed circuit board through FEM and 3 different thermal cycling tests. It has been found that the stress concentration around the encapsulated edge structure for internal crack between the silicon chip and Cu alloy die pad. And using 42 alloy clad, The reliability of TSOP body was improved. In case of using 42 alloy clad die pad(t=0.03mm). $$\sigma$_{VMmax}$ is 69Mpa. It is showed that 15% improvement of the strength in the TSOP body in comparison with using Cu alloy die pad $($\sigma$_{VMmax}$=81MPa). In solder joint of TSOP, the maximum equivalent plastic strain and Von Mises stress concentrate on the heel of solder fillet and crack was initiated in it's region and propagated through the interface between lead and solder. Finally, the modified Manson-Coffin equation and relationship of the ratio of $N_{f}$ to nest(η) and cumulative fracture probability(f) with respect to the deviations of the 50% fracture probability life $(N_{f 50%})$ were achieved.

  • PDF

Suggestion of the Prediction Model for Material Properties and Creep of 60~80MPa Grade High Strength Concrete (설계기준강도 60~80MPa급 고강도콘크리트의 재료 특성 및 크리프 예측모델식 제안)

  • Moon, Hyung-Jae;Koo, Kyung-Mo;Kim, Hong-Seop;Seok, Won-Kyun;Lee, Byeong-Goo;Kim, Gyu-Yong
    • Journal of the Korea Institute of Building Construction
    • /
    • v.18 no.6
    • /
    • pp.517-525
    • /
    • 2018
  • The construction of super tall building which structure is RC and must be certainly considered on column shortening estimation and construction reflected concrete creep has been increased. Regarding the Fck 60~80MPa grade high strength concrete applied in the domestic super tall building project, the mechanical properties and creep deflection according to curing conditions(Drying creep/Basic creep) were reviewed in this research. Results of compressive strength and elastic modulus under sealed curing condition were 5% higher than unsealed condition and difference of results according to the curing condition was increased over time. Autogenous and drying shrinkage tendency showed adversely in the case of high strength concrete. Additionally, creep modulus under unseal curing condition was evaluated 2~3 times higher than sealed condition. Modified model of ACI-209 based on test result was applied to estimate long period shortening of vertical members(such as Core Wall/Mega Column) exactly, it is designed to modify and suggest the optimal creep model based on various data accumulated during construction, in the future.

Prediction of Transmission Error Using Dynamic Analysis of a Helical Gear (헬리컬기어의 동적해석을 통한 전달오차 예측)

  • Lee, Jeongseok;Yoon, Moonyoung;Boo, Kwangsuk;Kim, Heungseob
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.40 no.12
    • /
    • pp.1005-1011
    • /
    • 2016
  • The fundamental reason for gear noise is transmission error. Transmission error occurs because of STE (static transmission error) and DTE (dynamic transmission error), while a pair of gears is meshing. These errors are generated by the deflection of the teeth and the friction on the surface of the teeth. In addition, the vibration generated by transmission error leads to excited bearings. The bearings support the shafts, and the noise is radiated after exciting the gear casing. The analysis of the contact stress in helical gear tooth flanks indicates that it is due to impact loading, such as the sudden engagement and disengagement of a gear. Stress analysis is performed for different roll positions, in order to determine the most critical roll angle. Dynamic analysis is performed on this critical roll position, in order to evaluate variation in stresses and tooth contact force, with respect to time. In this study, transmission error analysis was implemented on a spur and helical gear with involute geometry and a modified geometry profile. In addition, in order to evaluate the intensity of impact due to sudden engagement and significant backlash, the impact factor was calculated using the finite element analysis results of static and dynamic maximum bending stresses.