displacement curve
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2022 ◽  
pp. 136943322110723
Author(s):  
Yasir Ibrahim Shah ◽  
Zhijian Hu ◽  
Pengfei Yao

This paper presents an experimental study of a novel composite structure used in prefabricated bridges. Corrugated pipes were used to improve the interface bond performance of the structure because of their excellent stiffening effect on the grouting material. Interface bond performance of overlap joints within corrugated pipes was explored by the load-displacement curve and load-strain curves. Ultra-High Performance Concrete (UHPC) and high-strength mortar were used as grouting materials. The diameter of steel bars, UHPC, high-strength mortar, strength grades of surrounded concrete, anchorage length, the diameter of the corrugated pipe, and lap length was taken as influential factors. Twenty specimens were designed for the pull-out test by using a larger cover thickness. The failure modes and the influence of different influential factors on the interface bond strength of each specimen were analyzed. The results show that the bond performance between UHPC and reinforcement was better than that of high-strength mortar and normal concrete, which can effectively improve the bond strength and reduce the basic anchorage length of reinforcement besides the design size of prefabricated members. In addition, the differences in anchorage length and lap length between the corrugated pipe grouting reinforcement were compared to the different specifications and prefabricated concrete members. Combined with the test phenomenon and analysis results, it is suggested that the anchorage length and lap length of connecting reinforcement should be reconsidered. Furthermore, the grouting effect under different diameters of corrugated pipe and reinforcement were compared. It is recommended that the corrugated pipe diameter should be four times that of the overlapping grouting reinforcement.


PLoS ONE ◽  
2022 ◽  
Vol 17 (1) ◽  
pp. e0262156
Author(s):  
Georg Langen ◽  
Christine Lohr ◽  
Olaf Ueberschär ◽  
Michael Behringer

Tensiomyography measures the radial displacement of a muscle during an electrically evoked twitch contraction. The rate of muscle displacement is increasingly reported to assess contractile properties. Several formulas currently exist to calculate the rate of displacement during the contraction phase of the maximal twitch response. However, information on the reproducibility of these formulas is scarce. Further, different rest intervals ranging from 10 s to 30 s are applied between consecutive stimuli during progressive electrical stimulation until the maximum twitch response. The effect of different rest intervals on the rate of displacement has not been investigated so far. The first aim of this study is to investigate the within and between-day reliability of the most frequently used formulas to calculate the rate of displacement. The second aim is to investigate the effect of changing the inter-stimulus interval on the rate of displacement. We will determine the rectus femoris and biceps femoris rate of displacement of twenty-four healthy subjects’ dominant leg on two consecutive days. The maximum displacement curve will be determined two times within three minutes on the first day and a third time 24 h later. On day two, we will also apply three blocks of ten consecutive stimuli at a constant intensity of 50 mA. Inter-stimuli intervals will be 10 s, 20 s or 30 s in each block, respectively, and three minutes between blocks. The order of inter-stimulus intervals will be randomized. This study will allow a direct comparison between the five most frequently used formulas to calculate the rate of displacement in terms of their reproducibility. Our data will also inform on the effect of different inter-stimulus intervals on the rate of displacement. These results will provide helpful information on methodical considerations to determine the rate of displacement and may thus contribute to a standardized approach.


2022 ◽  
Vol 8 (1) ◽  
pp. 45-59
Author(s):  
Almoutaz Bellah Alsamawi ◽  
Nadir Boumechra ◽  
Karim Hamdaoui

This paper investigates the cyclic behaviour of steel-concrete encased composite columns. By investigating the cover concrete and the steel-concrete coefficient of friction on the behaviour (strength, ductility, stiffness, and energy dissipation) of composite columns subjected to combined axial load and cyclically increasing lateral load to improve the strength and performance of the composite column. Eight of the columns were designed to study the cover concrete effect, and eleven other columns were designed to study the coefficient of friction effect in the dynamic behaviour to the cyclic load. Additionally, in this study, the finite element models created in ANSYS software were verified and calibrated against previously published experimental results (load-displacement curve, load capacity and failure mode). The numerical results obtained from the finite element model indicate that the ductility and the energy dissipated increased by +11.71 and +18.93% receptively by the increase of the cover concrete until reaching the limit of the cover concrete. Beyond this limit, the ductility and the energy decrease by 27.33 and 24.97% receptively. The results also indicate that the ductility and the energy dissipated increased by 12.62 and 7.82% receptively by the increased coefficient of friction until reach 0.6, after that the energy decreases by 4.47%. Doi: 10.28991/CEJ-2022-08-01-04 Full Text: PDF


Actuators ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 9
Author(s):  
Seongkyu Chang ◽  
Sung Gook Cho

This study developed a nonlinear behavior prediction model for elasto-plastic steel coil dampers (SCDs) using artificial neural networks (ANN). To train the ANN, first, the input and output data of the behavior of the elasto-plastic SCD was prepared. This study utilized the design parameters and load–displacement curves of the SCD to train the ANN. The elasto-plastic load–displacement curve of the SCD was obtained from simulation results using an ANSYS workbench. The design parameters (wire diameter, internal diameter, number of active windings, yield strength) of the SCD were defined as the input patterns, while the yield deformation, first stiffness, and second stiffness were output patterns. During learning of the neural network model, 60 datasets of the SCD were used as the learning pattern, and the remaining 21 were used to verify the model. Although this study used a small number of learning patterns, the ANN predicted accurate results for yield displacement, first stiffness, and second stiffness. In this study, the ANN was found to perform very well, predicting the nonlinear response of the SCD, compared with the values obtained from a finite element analysis program.


The Holocene ◽  
2021 ◽  
pp. 095968362110665
Author(s):  
Triine Nirgi ◽  
Ieva Grudzinska ◽  
Edyta Kalińska ◽  
Marge Konsa ◽  
Argo Jõeleht ◽  
...  

Two unique Pre-Viking Age ship burials were found from Salme village, Saaremaa Island, eastern Baltic Sea, containing remains of seven men in the smaller and 34 men in the larger ship. According to the archaeological interpretations, these ships belonged to a viking crew possibly from the Stockholm-Mälaren region, eastern Sweden. Geoarchaeological research was conducted in the area to reconstruct Late-Holocene relative sea-level (RSL) changes and shoreline displacement to provide environmental context to these burials. In this paper we present a Late-Holocene shore displacement curve for the Saaremaa Island and GIS-based palaeogeographic reconstructions for the Salme area. The curve shows an almost linear RSL fall from 5.5 to 0.8 m a.s.l. between 1000 BC and 1300 AD with an average rate of 2 mm/year. A slowdown in regression may be attributed to accelerated sea-level rise after the Little Ice Age and during the industrial period, being consistent with the tide-gauge measurements from the 20th century. Palaeogeographic reconstructions indicate the existence of a strait in the Salme area during the burial of the ships. The eastern part of the strait with water depth up to 2.8 m was about 80–100 m wide. The relatively steep and wind-protected shores in that part of the strait were probably the best places in the area for landing the viking ships. According to sedimentological evidence and diatom data, the narrowing of Salme palaeostrait occurred between 1270 and 1300 AD. Salme I and II ships were buried at 650–770 AD into the sandy-gravelly coastal deposits which had accumulated there in the open coastal zone about 710–450 years earlier. Reconstructions show that the ships were located about 2–2.5 m above coeval sea level and more than 100 m from the coastline. Thus, both ships were probably moved from the shore to the higher ground for burial.


2021 ◽  
pp. 002199832110595
Author(s):  
Nastaran Bahrami-Novin ◽  
Ehsan Mahdavi ◽  
Mahdi Shaban ◽  
Hashem Mazaheri

Corrugated sheets with optimized mechanical properties are crucial for lightweight design in industrial applications. This study considered and optimized a corrugated sheet with a sinusoidal profile to enhance elastic modulus, tensile-bending coupling, and weight reduction. For this aim, first, flat specimens consisting of E-glass woven fiber and epoxy resin were made by hand lay-up method, following ASTM D3039. The tensile test determined young’s modulus of flat samples. Afterward, two molds with supports were fabricated. The corrugated specimens were constructed and exposed to a standard tensile test. The finite element analysis was used to simulate the tensile test of corrugated samples. The numerical force-displacement curve is derived from numerical analysis and verified by experimental results. After that, two multi-objective optimization problems, mass-constraint and global optimization, were implemented. Analytical formulations were verified by numerical and experimental results and utilized for optimization purposes. The genetic algorithm was used to examine and confirm trade-off behavior between objective functions. The Pareto fronts diagrams for mentioned two multi-objective optimization problem were obtained. Finally, the optimum parameters are calculated by using the LINMAP (Linear Programming Technique for Multi-dimensional Analysis of Preference) method.


Author(s):  
Kuo Ding ◽  
Hui Li

Over the past several years, a metal mine by block caving method has experienced a long-term and progressive surface deformation and fracturing, and then we start our investigation based on this background. The location of surface rupture was based on a series of mapping activities and the deformation data was collected by GPS from 2013 to 2016. In this paper, emphasis was put on the analysis of the fissures, deformation and stress of surface subsidence. Results reveal the diversity magnitude and structural features of surface deformation and ground fissures. In addition, the time dependent behavior is comprehended and the subsidence zone reflects different types of time-displacement curve – regressive phase, steady phase and progressive phase, all these achievements indicate the complexity and diversity of the subsidence zone. On the other hand, stress calculation which inspired from the mechanical model of the cracking of hole wall is carried out, it is meaningful to understand the relation between fracture features, displacement vectors and horizontal stress.


2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Yu Zou ◽  
Dong Xu

Joints that represent locations of discontinuity were the prominent factors affecting the overall behavior of precast segmental bridges. In this study, the steel shear key was designed, which was used to transmit the shear stress of the joints. To study the mechanical characteristics of the steel shear keyed joints in the construction and finished states, direct shear experiments and numerical analysis were carried out. The experimental results showed that the steel shear keyed joints had a high bearing capacity and good ductility. Under the action of confining stress, the joints relied on the mechanical occlusion between the steel keys to transmit the shear forces. When the load-displacement curve entered the horizontal stage, it can still bore large relative deformation, and the bearing capacity did not decrease. In the construction state, the inelastic deformation of the steel shear key should be used to control the design value of the temporary load. In the finished state, the bearing capacity of joints should be controlled by the direct shear strength of the steel shear key, which can be calculated according to the shear formula. The shear strength of the material and size of the steel shear key are the main factors affecting the bearing capacity of steel shear keyed joints.


2021 ◽  
Vol 28 (4) ◽  
pp. 133-141
Author(s):  
Xiaowen Li ◽  
Zhaoiy Zhu ◽  
Qinglin Chen ◽  
Yingqiang Cai ◽  
Miaojiao Peng

Abstract The stability of thin plate plays an important role in the design and strength check of ship structure. In order to study the shear stability of ship’s thin plates, in-plane shear buckling tests were carried out using a picture frame fixture and a 3D full-field strain measurement system. The critical buckling load, full-field displacement/strain information, and load-displacement curve were obtained. The finite element model with the frame fixture was established based on ABAQUS, with the eigenvalue buckling analysis and nonlinear buckling analysis being carried out to obtain the mechanical response information of the buckling and post-buckling of the ship’s thin plate. The effectiveness and accuracy of the numerical simulation method are verified by comparing the numerical simulation with the experimental results. On this basis, the critical buckling load obtained by shear test, numerical simulation, and theoretical calculation is analyzed, and the function of the frame shear fixture and its influence on the critical buckling load are defined. The research in this paper provides a useful reference for the testing and simulation of in-plane shear stability of ship’s thin plates.


2021 ◽  
Vol 26 (4) ◽  
pp. 156-166
Author(s):  
Amir Mahboob ◽  
Amir Reza Eskenati ◽  
Soheil Moradalizadeh

Abstract Fiber-reinforced polymer (FRP) has been commonly used to reinforce concrete structures. The kinds of FRP demonstrate an effective alternative to various methods of reinforcement in concrete structures subjected to bad environmental conditions which cause corrosion and damage to concrete. Due to their lightweight, high strength, and high corrosion and fatigue resistance, Fiber Reinforced Polymer (FRP) composites have been widely applied in steel substitution during revitalization interventions. This paper presents numerical three-points bending tests on different models to investigate the effect of the reinforcements; Carbon, Glass, and Aramid fibers to find the corresponding cost of each one. Also, there is an available experimental model for verifying the results of the FEM that demonstrated broad agreement with the experimental statement, concerning the load-displacement curve. After validating the models, alternative designs such as type of the FRP, position of the FRP, and amount of the FRP usage were numerically tested to study the influence of each on the load-bearing capacity. The results showed that the best configuration would be one with GFRP and the load-bearing capacity is around 9 kN in the optimum design.


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