Analytical research of beam-column joint behavior using simplified finite element modeling

<div class="section abstract"><div class="htmlview paragraph">The serpentine belt's multi-scale problems in geometric size, which gives rise to a very large number of element and deeply low calculating efficiency, always bring obstacles when predicting the dynamic response of a serpentine belt driving system using three-dimensional finite element model (FEM). In this paper, a simplified finite element model is built which can accurately present the original serpentine belt's geometric characteristics such as cross-area and moment of inertia, as well as material characteristics such as stiffness and damping, etc. This simplified model is then used in a three-dimensional belt-drive model to simulate the dynamic characteristics of the belt-drive system. The results show that the tension fluctuation for the original serpentine belt and the simplified belt are in good agreement with each other which confirms that the simplified belt model can be used to predict the engine front end accessory drive system (EFEADS)'s dynamic characteristics. Furthermore, the simplified belt has greatly improved the calculating efficiency as it reduces element number and the minimum element size and can be modelled more easily compared with the serpentine belt, so the simplified model has a very important engineering significance especially when it is applied to the complicated EFEADS.</div></div>

Experimental and numerical study of T-shaped irregularly concrete-filled steel tube columns under combined axial loads and moments

<div class="htmlview paragraph">Fatigue prediction of structures with a large number of spot welds requires simplified models for the spot welds. The simplified models should be able to deliver reliable stresses at the spot welds. This is actually still a challenge for the modeling techniques of spot welds. Based on recent research on the modeling techniques for spot welds and a nodal-force-based stress evaluation method, a simplified finite element model is developed for spot welds. The model can be applied to shell element models like automotive structures with coarse meshes and it is capable of delivering reliable stresses and stress intensity factors at spot welds which may be used for the fatigue predictions. The mesh-insensitivity of the model is also demonstrated.</div>

Hybrid RCS frames consisting of reinforced concrete (RC) column and steel (S) are used frequently in practice for mid- to high-rise buildings. RCS frames possess several advantages from structural, economical, and constructional view points compared to either traditional RC or steel frames. One of the key elements in RCS frames is the beam–column joints. This paper deals with numerical study on static response of a new reinforce concrete-steel (RCS) exterior beam–column joint. The studied beam–column joint detail is a through-column type in which an H steel profile totally embedded inside RC column is directly welded to the steel beam. The H steel profile was covered by two supplementary plates in the joint area. This detail provides two main advantages: The column is continuous, and no stirrups in the joint area are needed. The nonlinear behavior of the new joint is studied numerically and showed that this proposed joint is suitable as a special moment connection. In addition, the parametric studies are carried out to investigate the influences of the stirrups, the encased profile length, and supplementary plate length on the behavior of the joint.

Surface wave propagation effects on buried segmented pipelines

The problem of seismic response of buried pipeline aimed at the interaction of soil around the pipeline and the complicated calculation model was considered, and the various simplified finite element model was calculated, and it was analyzed. Firstly, the ADINA finite element analysis software was used. The four nodes in shell unit were used by tube. The spring unit was used by soil spring. The analysis model of buried pipeline finite element numerical based on tension and compression spring was established. Seismic wave was input. The response to the simple boundary, viscoelastic boundary earthquake were calculated and analyzed by the finite element numerical simulation. The pipeline’s earthquake ground motion response was obtained, and was compared with the real soil model, and the most suitable simplified calculation model for numerical analysis of buried pipeline was found, which was the numerical analysis model of buried pipeline pressure spring tension finite element based on the viscoelastic boundary, and the theory basis for the seismic design of pipeline was provided.

A comparative study of refined and simplified thermo-viscoplastic modeling of a thrust chamber with regenerative cooling

Hysteretic behavior of UHPC beam-column joints after fire exposure

The beam-column joint is an important component of Reinforced Concrete (RC) structures because its design and detailing are critical to the safety of these structures under seismic loading. In recent decades, structural behaviour of beam-column joints has been widely explored. To better understand the behaviour of beam-column joints, researchers have conducted experiments and provided analytical and experimental solutions. The seismic behaviour of beam-column joints with and without Glass Fibre Reinforced Polymer (GFRP) when subjected to quasi-static lateral cyclic loading was compared in this research using two specimens. The first specimen is a typical RC exterior beam-column joint without GFRP while the second specimen is RC exterior beam-column joint that is pre-installed with Glass Fibre Reinforced Polymer (GFRP) using Near-Surface Mounted (NSM) technique. The specimens were evaluated to a drift of 2.0% under quasi-static lateral cyclic loading. There were two cycles in each drift. Based on the amplitudes of both specimens, it can be seen that the amplitude of beam-column joint with GFRP is lower than the beam-column joint without GFRP. This suggests that the presence of GFRP reduces the intensity of the loading. This study also discusses the energy dissipation and equivalent viscous damping on both specimens. During the experiment, each crack, void between the concrete, and spalling of concrete fragments were carefully monitored. Visual observation during the experiment shows that severe cracking is evident on the inner part of the structure in both specimens. Therefore, a new location of GFRP-NSM would be suggested for a future experiment.

In this paper, a simplified aircraft system model is developed correctly emulating the nonlinear dynamics of complex aircraft models under closed-loop control. The simplified model is based on Dubins models used in optimization algorithms for trajectory control of multiple Unmanned Aeriel Vehicles (UAVs). Algorithms optimizing area coverage for reconnaissance based on UAV capabilities, fuel remaining, and time constraints require simple aircraft models providing ecient solutions in near real-time. However, the simplified models should accurately predict UAV dynamics for proper prediction. For this study, a realistic UAV simulation is developed including nonlinear aerodynamics and kinematics. A UAV autonomous navigation algorithm for waypoint-to-waypoint navigation is derived and integrated in the complex UAV simulation. A simplified system model based Dubins model is developed closely matching the full nonlinear UAV simulation. A Rhumb-line navigation algorithm including a velocity-hold and altitude-hold control system is used for closed-loop control. A navigation system utilizing trajectory planning with Dubins curves is also developed. Both control laws are implemented in a simplified Dubins model and tuned to match the full nonlinear simulation under autonomous control including provisions for head and tail wind conditions. Computer simulations are performed demonstrating waypointto-waypoint navigation with desired final heading trajectories for both the full nonlinear UAV model and the simplified Dubins simulation. Simulation time history analysis is used to verify the accuracy of the simplified model compared to the full nonlinear simulation model.

: Stress analyses of lumbar vertebrae were performed by a three dimensional finite element method for the purposes of (i) evaluating simplified models of the vertebrae which are suitable as injury post processors, and (ii) gaining a better understanding of injury mechanisms. The finite element analyses were linear and elastic. Axial and moment loads were applied over the end plates to simulate G sub z impact and on the facets to simulate load transmission between the articular facets and the vertebral bodies. The finite element model predicts that the maximum stresses under axial load are perpendicular to the axis of the vertebral body, which are called axial stresses; this is consistent with the predominance of compressive and wedge fractures. However, the maximum stresses predicted by the finite element model are only about a third of those predicted by the simplified injury model. This discrepancy is due to the fact that a substantial portion of the total load is transmitted through the vertebral centrum which is neglected in the simplified model. Furthermore, the finite element model exhibits a rather complex pattern of deformation even under axial load, which cannot be incorporated easily in a simplified model. The stresses predicted by the finite element model for bending also differ substantially from those given by the simplified model for the same reasons. Good agreement between the finite element model and simplified model is only achieved for torsion loads.

Simplified equivalent finite element modelling of concrete-filled steel tubular K-joints with and without studs

Dependence of the AES backscattering correction factor on the experimental configuration

One method for simplified manipulator model construction and its application in quazioptimal trajectory synthesis

This study investigates the dynamic performance of a large‐span suspended steel space frame‐glass composite floor (SSSF‐GCF). Both the ambient vibration and the human‐induced vibration of the floor were experimentally measured to identify vertical dynamic characteristics and evaluate vibration serviceability of the floor. Although vertical dynamic characteristics of the floor based on the global simplified finite element (FE) model of the structure agree well with those identified via experimental modal analysis, the global simplified FE model significantly underestimates vertical vibration amplitudes of the floor due to the coupled effect between two layers. Accordingly, an equivalent local FE model of the floor system was proposed and updated via adjusting the vertical stiffness of the interstory hanging pillars. It is shown that the equivalent local FE model can well predict both the dynamic characteristics and human‐induced vibration response of the floor. Finally, the effect of the damping ratio on the acceleration response of the floor was numerically demonstrated with the verified local FE model.