PERFORMANCE OF PRESTRESSED CONCRETE BEAM INCORPORATING AN AXIAL YIELD DAMPER USING UNBONDED REBAR

Unbonded prestressed concrete (UBPC) has shown considerable promise for structural elements in continuous-use applications. However, little research has evaluated the performance of UBPC structural elements or their low energy absorption ability, and such elements are therefore not commonly used as main structural members. In this study, a small axially yielding hysteresis damper was developed, which can be replaced in the event of earthquake damage to a UBPC beam in high continuous use. The damper was designed to use the axial yielding of deformed rebars so that it has the same performance under compressive and tensile forces. It was mounted in a knee brace shape and had a mass of about 10 kg. The damper exhibited positive and negative hysteresis characteristics even after the deformed rebars had yielded axially and it had sufficient energy absorption capacity. In a structural experiment, installing the damper, the shear force that can be borne by the beam and the equivalent damping constant increased, which means that the damper is useful.

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Study of Energy Absorption Characteristics of Square Tube With Composite Cellular Core

Volume 9: Mechanics of Solids, Structures, and Fluids ◽

10.1115/imece2018-86916 ◽

2018 ◽

Author(s):

Muhammad Ali ◽

Eboreime Ohioma ◽

Khairul Alam

Keyword(s):

Energy Absorption ◽

Compressive Loading ◽

Absorption Capacity ◽

Structural Members ◽

Tubular Structures ◽

Tube Material ◽

Energy Absorption Capacity ◽

Core Tube ◽

Energy Absorbing ◽

Deformation Modes

Square tubes are primarily used in automotive structures to absorb energy in the event of an accident. The energy absorption capacity of these structural members depends on several parameters such as tube material, wall thickness, axial length, deformation modes, locking strain, crushing stress, etc. In this paper, the work presented is a continuation of research conducted on exploring the effects of the introduction of cellular core in tubular structures under axial compressive loading. Here, the crushing response of composite cellular core tube was numerically studied using ABAQUS/Explicit module. The energy absorbing characteristics such as deformation or collapsing modes, crushing/ reactive force, crushing stroke, and energy curves were discussed. The composite cellular core tube shows promise for improving the crashworthiness of automobiles.

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Torsion of Reinforced Concrete Structural Members

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.272.178 ◽

2018 ◽

Vol 272 ◽

pp. 178-184

Author(s):

Vladimír Křístek ◽

Jaroslav Průša ◽

Jan L. Vítek

Keyword(s):

Bending Moments ◽

Structural Elements ◽

Structural Members ◽

Structural System ◽

Shear Forces ◽

Axial Forces ◽

Methods Of Calculation ◽

Tensile Forces ◽

Torque Capacity ◽

The Common

According to the common design methods of calculation of the stress state induced by torsion of massive prismatic concrete structural elements, the structural system is reduced to a simple cage consisting of ties and struts. This model has, however, a number of principal shortcomings, the major of them is the fact that all of simultaneously acting effects like axial forces, bending moments and shear forces are not taken into account – the compressive axial forces increase very significantly the torque capacity of structural members, while due to action of tensile forces, bending moments and shear forces the torque capacity is reduced. These phenomena, applying non-linear approaches, are analysed and assessed.

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The energy distribution of a train impact process based on the active–passive energy-absorption method

Transportation Safety and Environment ◽

10.1093/transp/tdz002 ◽

2019 ◽

Vol 1 (1) ◽

pp. 54-67 ◽

Cited By ~ 1

Author(s):

Gao Guangjun

Keyword(s):

Energy Distribution ◽

Simulation Model ◽

Energy Absorption ◽

Impact Velocity ◽

Absorption Capacity ◽

Simulation Software ◽

Passive Safety ◽

Absorption Method ◽

Sufficient Energy ◽

Absorption Characteristics

Abstract This paper examines the energy-absorption characteristics of trains for active–passive safety protection. A one-dimensional collision-simulation model of traditional subway vehicles and active–passive safety vehicles was developed based on the multibody dynamics theory using MATLAB simulation software. The effectiveness of the simulation model was verified by scaled-collision tests. Then, the energy-absorption characteristics of traditional trains and the active–passive safety trains under different marshalling conditions were studied. The results showed that as the number of marshalling vehicles increased from 5 to 8, the energy absorption of interface 1 for the active–passive safety trains during the collision was 681 kJ, 775 kJ, 840 kJ and 901 kJ, and the physical compression of the interface of the head car of the active–passive safety trains was 619 mm, 704 mm, 764 mm and 816 mm, which was far below the maximum value of 1773 mm. The head car of the active–passive safety subway vehicles therefore had sufficient energy-absorption capacity. Finally, to find the maximum safe impact velocity of the active–passive safety trains, the energy distribution of the active–passive safety subway vehicles with 8-car marshalling at different impact velocities was studied. It was found that the safe impact velocity of an active–passive safety subway vehicle conforming to the requirements of the EN15227 collision standard reached 32 km/h, far exceeding the safe impact velocity of 25 km/h allowed by traditional trains, and representing an increase in the safe impact velocity of 28%. The total collision-energy absorption of the interface of the head car of the active–passive trains was 89.1% higher than that of the traditional trains at the safe impact velocity. The active–passive energy absorption method was therefore effective at improving the crashworthiness of the subway trains.

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Overview of the modified magnetoelastic method applicability

ACTA IMEKO ◽

10.21014/acta_imeko.v10i3.1071 ◽

2021 ◽

Vol 10 (3) ◽

pp. 167

Author(s):

Tomáš Klier ◽

Tomáš Mícka ◽

Michal Polák ◽

Milan Hedbávný

Keyword(s):

Prestressed Concrete ◽

Concrete Structures ◽

Engineering Practice ◽

Structural Elements ◽

Engineering Structures ◽

Advantages And Disadvantages ◽

Axial Forces ◽

Technical Practice ◽

Tensile Forces

<p class="Abstract">A requirement of axial force determination in important structural elements of a building or engineering structure during its construction or operational state is very frequent in technical practice. In civil engineering practice, five experimental techniques are usually used for evaluation of axial tensile forces in these elements. Each of them has its advantages and disadvantages. One of these methods is the magnetoelastic method, that can be used, for example, on engineering structures for experimental determination of the axial forces in prestressed structural elements made of ferromagnetic materials, e.g., prestressed bars, wires and strands. The article presents general principles of the magnetoelastic method, the magnetoelastic sensor layout and actual information and knowledge about practical application of the new approach based on the magnetoelastic principle on prestressed concrete structures. Subsequently, recent results of the experimental verification and the in-situ application of the method are described in the text. The described experimental approach is usable not only for newly built structures but in particular for existing ones. Furthermore, this approach is the only one effectively usable experimental method for determination of the prestressed force on existing prestressed concrete structures in many cases in the technical practice.</p>

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Evaluation Method of Seismic Performance Using Energy Absorption Capacity

IABSE Symposium Report ◽

10.2749/222137801796348953 ◽

2001 ◽

Vol 85 (4) ◽

pp. 1-6

Author(s):

Nobuyoshi Yamaguchi ◽

Chikahiro Minowa

Keyword(s):

Energy Absorption ◽

Seismic Performance ◽

Evaluation Method ◽

Absorption Capacity ◽

Energy Absorption Capacity

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Numerical and experimental investigation for enhancing the energy absorption capacity of the novel three-dimensional printed sandwich structures

Proceedings of the Institution of Mechanical Engineers Part L Journal of Materials Design and Applications ◽

10.1177/1464420721997490 ◽

2021 ◽

pp. 146442072199749

Author(s):

H Geramizadeh ◽

S Dariushi ◽

S Jedari Salami

Keyword(s):

Energy Absorption ◽

Sandwich Structures ◽

Three Dimensional ◽

Absorption Capacity ◽

The Novel ◽

Energy Absorption Capacity ◽

Fused Deposition ◽

Honeycomb Sandwich ◽

Out Of Plane ◽

Vertical Walls

The current study focuses on designing the optimal three-dimensional printed sandwich structures. The main goal is to improve the energy absorption capacity of the out-of-plane honeycomb sandwich beam. The novel Beta VI and Alpha VI were designed in order to achieve this aim. In the Beta VI, the connecting curves (splines) were used instead of the four diagonal walls, while the two vertical walls remained unchanged. The Alpha VI is a step forward on the Beta VI, which was promoted by filleting all angles among the vertical walls, created arcs, and face sheets. The two offered sandwich structures have not hitherto been provided in the literature. All models were designed and simulated by the CATIA and ABAQUS, respectively. The three-dimensional printer fabricated the samples by fused deposition modeling technique. The material properties were determined under tensile, compression, and three-point bending tests. The results are carried out by two methods based on experimental tests and finite element analyses that confirmed each other. The achievements provide novel insights into the determination of the adequate number of unit cells and demonstrate the energy absorption capacity of the Beta VI and Alpha VI are 23.7% and 53.9%, respectively, higher than the out-of-plane honeycomb sandwich structures.

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Dynamic crushing behavior of closed-cell aluminum foams based on different space-filling unit cells

Archives of Civil and Mechanical Engineering ◽

10.1007/s43452-021-00251-1 ◽

2021 ◽

Vol 21 (3) ◽

Author(s):

S. Talebi ◽

R. Hedayati ◽

M. Sadighi

Keyword(s):

Surface Area ◽

Dynamic Behavior ◽

Energy Absorption ◽

Peak Stress ◽

Absorption Capacity ◽

Unit Cell ◽

Lattice Structures ◽

Energy Absorption Capacity ◽

Closed Cell ◽

Unit Cells

AbstractClosed-cell metal foams are cellular solids that show unique properties such as high strength to weight ratio, high energy absorption capacity, and low thermal conductivity. Due to being computation and cost effective, modeling the behavior of closed-cell foams using regular unit cells has attracted a lot of attention in this regard. Recent developments in additive manufacturing techniques which have made the production of rationally designed porous structures feasible has also contributed to recent increasing interest in studying the mechanical behavior of regular lattice structures. In this study, five different topologies namely Kelvin, Weaire–Phelan, rhombicuboctahedron, octahedral, and truncated cube are considered for constructing lattice structures. The effects of foam density and impact velocity on the stress–strain curves, first peak stress, and energy absorption capacity are investigated. The results showed that unit cell topology has a very significant effect on the stiffness, first peak stress, failure mode, and energy absorption capacity. Among all the unit cell types, the Kelvin unit cell demonstrated the most similar behavior to experimental test results. The Weaire–Phelan unit cell, while showing promising results in low and medium densities, demonstrated unstable behavior at high impact velocity. The lattice structures with high fractions of vertical walls (truncated cube and rhombicuboctahedron) showed higher stiffness and first peak stress values as compared to lattice structures with high ratio of oblique walls (Weaire–Phelan and Kelvin). However, as for the energy absorption capacity, other factors were important. The lattice structures with high cell wall surface area had higher energy absorption capacities as compared to lattice structures with low surface area. The results of this study are not only beneficial in determining the proper unit cell type in numerical modeling of dynamic behavior of closed-cell foams, but they are also advantageous in studying the dynamic behavior of additively manufactured lattice structures with different topologies.

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Static Mechanical Properties of Expanded Polypropylene Crushable Foam

Materials ◽

10.3390/ma14020249 ◽

2021 ◽

Vol 14 (2) ◽

pp. 249

Author(s):

Przemysław Rumianek ◽

Tomasz Dobosz ◽

Radosław Nowak ◽

Piotr Dziewit ◽

Andrzej Aromiński

Keyword(s):

Mechanical Properties ◽

Compressive Strength ◽

Strain Rate ◽

Energy Absorption ◽

Experimental Tests ◽

Absorption Capacity ◽

Strain Rates ◽

Foam Density ◽

Energy Absorption Capacity ◽

Closed Cell

Closed-cell expanded polypropylene (EPP) foam is commonly used in car bumpers for the purpose of absorbing energy impacts. Characterization of the foam’s mechanical properties at varying strain rates is essential for selecting the proper material used as a protective structure in dynamic loading application. The aim of the study was to investigate the influence of loading strain rate, material density, and microstructure on compressive strength and energy absorption capacity for closed-cell polymeric foams. We performed quasi-static compressive strength tests with strain rates in the range of 0.2 to 25 mm/s, using a hydraulically controlled material testing system (MTS) for different foam densities in the range 20 g/dm3 to 220 g/dm3. The above tests were carried out as numerical simulation using ABAQUS software. The verification of the properties was carried out on the basis of experimental tests and simulations performed using the finite element method. The method of modelling the structure of the tested sample has an impact on the stress values. Experimental tests were performed for various loads and at various initial temperatures of the tested sample. We found that increasing both the strain rate of loading and foam density raised the compressive strength and energy absorption capacity. Increasing the ambient and tested sample temperature caused a decrease in compressive strength and energy absorption capacity. For the same foam density, differences in foam microstructures were causing differences in strength and energy absorption capacity when testing at the same loading strain rate. To sum up, tuning the microstructure of foams could be used to acquire desired global materials properties. Precise material description extends the possibility of using EPP foams in various applications.

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