Search results for "LOAD"
showing 10 items of 1967 documents
Theoretical approaches for modelling buckling effects in rebars of RC members
2017
Buckling of longitudinal bars in reinforced concrete (RC) members is definitely a critical issue in framed structures subjected to seismic loads. Second order effects can affect the compressive stressâstrain law of steel bars, influencing ductility calculations of RC structures. Moreover, literature studies show that buckling can occur over a length wider than stirrupsâ pitch (global buckling mode), involving more stirrups and inducing large deflections in the bar. If the critical length is not carefully estimated, stirrupsâ failure can occur, causing also the sudden loss of confining effects in concrete. This paper presents the results of different approaches for calculating the crit…
Simplified Procedure for Evaluating the Effects of Creep and Shrinkage on Prestressed Concrete Girder Bridges and the Application of European and Nor…
2013
The effects of time-dependent phenomena on concrete prestressed girder bridges are investigated. The study concerns the case of bridges built directly in their final configuration and that of bridges built by a sequence of stages in which geometry, restraints, and loads vary until the final configuration is achieved. An analytical approach based on the principles of aging linear viscoelasticity and the age-adjusted effective modulus method is followed. The paper has two aims: the first is to provide an efficient and simplified tool for the evaluation of the structural response in the early stages of design; the second is to compare the results of the analyses on actual cases of bridges when…
Load-carrying capacity of axially-loaded RC members with circular openings
2012
Abstract Core drilling is today one of the most used technique among the group of partially destructive testing methods in reinforced concrete (RC) members. Even if the engineering practice provided to extract cores only in beams, taking samples from columns could be often necessary. In this case, the presence of the hole introduced a geometrical discontinuity in the member, creating a disturbed region. Consequently, compressive stresses will disperse in lateral direction as they have to avoid the drilled area. A bursting tensile force will develop, in orthogonal direction to the column axis, and if no sufficient reinforcement was arranged, a vertical crack will form, leading to the concret…
Development of 3D Anti-Swing Control for Hydraulic Knuckle Boom Crane
2021
In this paper, 3D anti-swing control for a hydraulic loader crane is presented. The difference between hydraulic and electric cranes are discussed to show the challenges associated with hydraulic actuation. The hanging load dynamics and relevant kinematics of the crane are derived to model the system and create the 3D anti-swing controller. The anti-swing controller generates a set of tool point velocities which are added to the electro-hydraulic motion controller via feedforward. A dynamic simulation model of the crane is made, and the control system is evaluated in simulations with a path controller in actuator space. Simulation results show significant reduction in the load swing angles …
Energy efficient operation in smart grids: optimal management of shiftable loads and storage systems
2012
In this paper, the authors analyze the impact of the participation of customers to the sustainable implementation of energy rational strategies in microgrids. The management of shiftable loads is compared to the control of real and reactive storage systems in smart grids. An optimization algorithm is used as analysis tool to assess the impact of such control variables in different conditions. The results clearly indicate that if shiftable loads are of suitable size, they have a more promising as tools to both reduce losses and to flatten the peak load through the HV/MV bus. Many tests have been carried out on a real experimental MV system in the area of Rome Italy.
Dimensionless analysis of RC rectangular sections under axial load and biaxial bending
2012
This paper proposes a numerical procedure able to provide ultimate curvature and moment domains of rectangular RC sections subjected to combined axial load and biaxial bending. The formulation is carried out in dimensionless terms in order to give results that are valid for classes of sections characterized by the same values of the geometric and mechanical parameters governing the section response. The role of some of these parameters is investigated here. The results show possible correlations linking the actual values of moment and curvature to the values corresponding to two cases of uniaxial bending to be considered separately. © 2012 Elsevier Ltd.
Unidirectional Direct Load Control through Smart Plugs
2014
International audience; Balancing energy demand and production is be-coming a more and more challenging task for energy utilities also because of the larger penetration of renewable energies which are more difficult to predict and control. While the traditional solution is to dynamically adapt energy production to follow time-varying demand, a new trend is to drive demand itself. Most of the ongoing actions in this direction involve greedy energy consumers, like industrial plants, supermarkets or large buildings. Pervasive communication technologies may allow in the near future to push further the granularity of such approach, by having the energy utility interacting with residen-tial appli…
Measurement-based load modelling for power supply system design
2008
Load modelling is essential to simulate system features as closely as possible to the effective behaviour. In spite of model complexity, the need for accuracy often leads to a component-based approach, i.e. the analysis of load internal subsystems. It is a common belief that measurement-based load models lead to low accuracy. This paper presents a new, high-accuracy measurement-based load modelling approach to define a power consumption profile load model for power systems design. The load modeling technique is described by an application. Simulation and experimental results are compared. The efficiency and portability of the proposed modelling approach is discussed. ©2008 IEEE.
A measurement methodology for monitoring a CHCP pilot plant for an office building
2003
Abstract In Mediterranean areas, climate conditions determine quite equal demand both for thermal and cooling energy. The possibility to convert a cooling demand in thermal one through an absorption chiller allows to extend widely the number of running hours of a cogeneration plant. A trigeneration pilot plant for two office building is described, in which an integrated lay-out includes a NG prime mover with heat exchanger, an absorption chiller and a reversible heat pump. The pilot plant is completed and pre-running test were performed. Different fluid dynamics parameters will be monitored, in order to build the actual cumulative curve for thermal power. The measurement methodology is also…
Using input shaping and pressure feedback to suppress oscillations in slewing motion of lightweight flexible hydraulic crane
2015
This paper presents a method to actively reduce vibrations in the flexible mechanical structure of a hydraulically actuated vehicle loader crane. Based on information on the natural frequency and damping of a simplified model of the crane an input shaping scheme is set up to control the proportional valve leading to substantially reductions in oscillations. The method is compared and combined with a pressure feedback control of the proportional valve that actively suppresses transient variations in pressure. A full scale vehicle loader crane is used in the experimental verification of the method, and the motion of the tool point of the crane is measured by a high precision laser tracker. Th…