scholarly journals Design and Manufacturing Loading Rig Machine for Testing Screw Pile Models

2018 ◽  
Vol 7 (4.20) ◽  
pp. 420 ◽  
Author(s):  
Mahmood R. Mahmood ◽  
Asad H. Humaish ◽  
Mustafa K. Khalaf
Keyword(s):  
Load Capacity ◽  
Vertical Displacement ◽  
Vertical Movement ◽  
Steel Plates ◽  
Ball Screw ◽  
Cohesionless Soil ◽  
Actual Behavior ◽  
Loading Test ◽  
Tension Load ◽  
Screw Pile

The main objective of this paper is to design, manufacturing and testing of new loading rig machine to install and testing (i.e. compression and tension load capacity) of screw pile models in both cohesive and cohesionless soil layers. The mainframe  was fabricated from thick steel sections, 8mm steel plates that welded together to construct a heavy and strong frame, that able to resist the expected loads during installation (linear and rotational movement at the same time) and testing of the screw pile models (model of loading test). Two independent gearbox motors (actuators) are used to supply the rotational and vertical movement.  To provide precise control of velocity, the master gearbox motor, that can convert the rotary motion to a linear motion for vertical displacement  along two screw bars via two ball screw systems,  and four stainless guided rods to prevent rotation or inclination the bearing plate (rig) which manufactured from high stiffness stainless-steel was used. The second gearbox motor (‘slave’) mounted on the bottom loading plate that rotates the multi-plate screw pile. It was observed that the measured compression and tension load capacity of screw pile models illustrated the actual behavior of such kind of piles and this machine can be used in both conventional piles (i.e. pipe piles) and screw pile model.  

scholarly journals Comparative Study of High-Performance Concrete Characteristics and Loading Test of Pretensioned Experimental Beams

Crystals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 427
Author(s):  
Pavlina Mateckova ◽  
Vlastimil Bilek ◽  
Oldrich Sucharda
Keyword(s):  
Mechanical Properties ◽  
High Performance ◽  
High Performance Concrete ◽  
Raw Materials ◽  
Load Capacity ◽  
Materials Testing ◽  
Loading Test ◽  
Conventional Concrete ◽  
Concrete Mechanical Properties ◽  
Normal Strength

High-performance concrete (HPC) is subjected to wide attention in current research. Many research tasks are focused on laboratory testing of concrete mechanical properties with specific raw materials, where a mixture is prepared in a relatively small amount in ideal conditions. The wider utilization of HPC is connected, among other things, with its utilization in the construction industry. The paper presents two variants of HPC which were developed by modification of ordinary concrete used by a precast company for pretensioned bridge beams. The presented variants were produced in industrial conditions using common raw materials. Testing and comparison of basic mechanical properties are complemented with specialized tests of the resistance to chloride penetration. Tentative expenses for normal strength concrete (NSC) and HPC are compared. The research program was accomplished with a loading test of model experimental pretensioned beams with a length of 7 m made of ordinarily used concrete and one variant of HPC. The aim of the loading test was to determine the load–deformation diagrams and verify the design code load capacity calculation method. Overall, the article summarizes the possible benefits of using HPC compared to conventional concrete.

scholarly journals Long-term bending properties of cross-laminated timber made from Japanese larch under constant environment

2021 ◽  
Vol 67 (1) ◽  
Author(s):  
Ryuya Takanashi ◽  
Yoshinori Ohashi ◽  
Wataru Ishihara ◽  
Kazushige Matsumoto
Keyword(s):  
Load Capacity ◽  
Creep Rupture ◽  
Japanese Larch ◽  
Larix Kaempferi ◽  
Loading Capacity ◽  
Loading Test ◽  
Cross Laminated Timber ◽  
Duration Of Load ◽  
Rupture Behavior

AbstractCross-laminated timber (CLT) has been used extensively in timber construction. CLT panels are typically used in roofs and floors that carry a continuous load, and it is important to examine the long-term loading capacity of CLT. However, studies that focus on the long-term loading capacity of CLT are limited. To this end, we conducted long-term out-of-plane bending tests on seven-layer CLT made from Japanese larch (Larix kaempferi) under constant environmental conditions, investigated creep performance and duration of load, and experimentally analyzed creep rupture behavior. The mean estimated relative creep after 50 years was 1.49. The sample showed a satisfactory resistance to creep as a building material. The duration of load of most of the specimens in this study was shorter than the conventional value of small clear wood specimens. Specimens had a lower duration of load capacity than solid lumber. According to the results of survival analysis, a loading level of 70% or more caused the initial failure of specimens. Creep rupture of most of the specimens occurred at less deflection than displacement at failure in the short-term loading test. Additional studies focusing on the effects of finger joints, transverse layers, and width of a specimen on creep rupture behavior are suggested.

scholarly journals Response of tapered piles in cohesionless soil based on model tests

2010 ◽  
Vol 40 ◽  
pp. 85-92 ◽  
Author(s):  
Suman Manandhar ◽  
Noriyuki Yasufuku ◽  
Kiyoshi Omine ◽  
Taizo Kobayashi
Keyword(s):  
Skin Friction ◽  
Model Tests ◽  
High Density ◽  
Cohesionless Soil ◽  
Cohesionless Soils ◽  
Loading Test ◽  
Tapered Pile ◽  
Different Types ◽  
Steel Piles ◽  
Settlement Ratio

This paper describes model tests of different types of tapered piles in cohesionless soils. Chromium plated three steel piles, one straight and two taper-shaped piles of same length and pile tip diameters have been executed for pile loading test in a downward frictional mode. Two different types of model grounds have been prepared for the test. Relative densities of 80 % and 60 % have been modeled to penetrate piles in two different types of sands to observe the effectiveness of skin frictions of different types of piles. The response of tapered piles has shown that the skin friction has increased with increasing the tapering angle at normalized settlement ratio of 0.4. High density ground yields higher skin friction when the maximum tapered pile was penetrated. Slightly increased tapering angle of the pile affects remarkably on the skin friction with compared to conventional straight cylindrical pile even at small 0.1 settlement ratios.

scholarly journals Ocean acidification changes the vertical movement of stone crab larvae

2019 ◽  
Vol 15 (12) ◽  
pp. 20190414 ◽  
Author(s):  
Philip M. Gravinese ◽  
Ian C. Enochs ◽  
Derek P. Manzello ◽  
Robert van Woesik
Keyword(s):  
Elevated Temperature ◽  
Developmental Stages ◽  
Anthropogenic Activities ◽  
Vertical Displacement ◽  
Vertical Movement ◽  
Larval Transport ◽  
Stage Iii ◽  
Coastal Habitats ◽  
Stone Crab ◽  
Seawater Ph

Anthropogenic activities are increasing ocean temperature and decreasing ocean pH. Some coastal habitats are experiencing increases in organic runoff, which when coupled with a loss of vegetated coastline can accelerate reductions in seawater pH. Marine larvae that hatch in coastal habitats may not have the ability to respond to elevated temperature and changes in seawater pH. This study examined the response of Florida stone crab ( Menippe mercenaria ) larvae to elevated temperature (30°C control and 32°C treatment) and CO 2 -induced reductions in pH (8.05 pH control and 7.80 pH treatment). We determined whether those singular and simultaneous stressors affect larval vertical movement at two developmental stages. Geotactic responses varied between larval stages. The direction and rate of the vertical displacement of larvae were dependent on pH rather than temperature. Stage III larvae swam upwards under ambient pH conditions, but swam downwards at a faster rate under reduced pH. There was no observable change in the directional movement of Stage V larvae. The reversal in orientation by Stage III larvae may limit larval transport in habitats that experience reduced pH and could pose challenges for the northward dispersal of stone crabs as coastal temperatures warm.

scholarly journals An Experimental and Numerical Study on the Flexural Performance of Over-Reinforced Concrete Beam Strengthening with Bolted-Compression Steel Plates: Part II

2019 ◽  
Vol 10 (1) ◽  
pp. 94 ◽  
Author(s):  
Shatha Alasadi ◽  
Zainah Ibrahim ◽  
Payam Shafigh ◽  
Ahad Javanmardi ◽  
Karim Nouri
Keyword(s):  
Failure Modes ◽  
Steel Plate ◽  
Numerical Study ◽  
Load Capacity ◽  
Plate Thickness ◽  
Steel Plates ◽  
Experimental Program ◽  
Failure Characteristics ◽  
Control Beam ◽  
Concrete Failure

This study presents an experimental investigation and finite element modelling (FEM) of the behavior of over-reinforced simply-supported beams developed under compression with a bolt-compression steel plate (BCSP) system. This study aims to avoid brittle failure in the compression zone by improving the strength, strain, and energy absorption (EA) of the over-reinforced beam. The experimental program consists of a control beam (CB) and three BCSP beams. With a fixed steel plate length of 1100 mm, the thicknesses of the steel plates vary at the top section. The adopted plate thicknesses were 6 mm, 10 mm, and 15 mm, denoted as BCSP-6, BCSP-10, and BCSP-15, respectively. The bolt arrangement was used to implement the bonding behavior between the concrete and the steel plate when casting. These plates were tested under flexural-static loading (four-point bending). The load-deflection and EA of the beams were determined experimentally. It was observed that the load capacity of the BCSP beams was improved by an increase in plate thickness. The increase in load capacity ranged from 73.7% to 149% of the load capacity of the control beam. The EA was improved up to about 247.5% in comparison with the control beam. There was also an improvement in the crack patterns and failure modes. It was concluded that the developed system has a great effect on the parameters studied. Moreover, the prediction of the concrete failure characteristics by the FE models, using the ABAQUS software package, was comparable with the values determined via the experimental procedures. Hence, the FE models were proven to accurately predict the concrete failure characteristics.

Design of a Compact, Lightweight, Electromechanical Linear Series Elastic Actuator

2014 ◽  
Author(s):  
Coleman Knabe ◽  
Bryce Lee ◽  
Viktor Orekhov ◽  
Dennis Hong
Keyword(s):  
Elastic Element ◽  
Load Capacity ◽  
Ball Screw ◽  
Leaf Spring ◽  
Load Range ◽  
Compression Load ◽  
Design Changes ◽  
Series Elastic Actuators ◽  
Future Work ◽  
Series Elastic

Series Elastic Actuators (SEAs) have several benefits for force controlled robotic applications. Typical SEAs place an elastic element between the motor and the load, increasing shock tolerance, allowing for more accurate and stable force control, and creating the potential for energy storage. This paper presents the design of a compact, lightweight, low-friction, electromechanical linear SEA used in the lower body of the Tactical Hazardous Operations Robot (THOR). The THOR SEA is an evolutionary improvement upon the SAFFiR SEA [1]. Design changes focused on reducing the size and fixed length of the actuator while increasing its load capacity. This SEA pairs a ball screw-driven linear actuator with a configurable elastic member. The elastic element is a titanium leaf spring with a removable pivot, setting the compliance to either 650 or 372 [kN/m]. The compliant beam is positioned parallel to the actuator, reducing overall packaging size by relocating the space required for spring deflection. Unlike typical SEAs which measure force through spring deflection, the force applied to the titanium beam is measured through a tension/compression load cell located in line with each actuator, resulting in a measurable load range of +/−2225 [N] at a tolerance of +/−1 [N]. A pair of universal joints connects the actuator to the compliant beam and to the robot frame. As the size of each universal joint is greatly dependent upon its required range of motion, each joint design is tailored to fit a particular angle range to further reduce packaging size. Potential research topics involving the actuator are proposed for future work.

Study on Positioning Accuracy of Aerostatic Lead Screw

Tribology ◽  
2006 ◽  
Author(s):  
Tadaatsu Satomi ◽  
Peng Zhao ◽  
Daisuke Kobayashi
Keyword(s):  
Load Capacity ◽  
Vital Role ◽  
Ball Screw ◽  
Machining Accuracy ◽  
Contact Type ◽  
Lead Screw ◽  
Guidance Theory ◽  
Static Rigidity ◽  
Semiconductor Fabrication ◽  
Air Film

The aerostatic lead screw is a non-contact type lead screw in which the contact surface of a male screw and a female screw is supported by a pressurized air film. It is characterized by the features that: (1) there is no degradation in accuracy due to friction wear; (2) no environmental pollution is caused by a leak and scattering of lubrication fluid; and (3) maintenance is easy and simple. However, drawbacks are that vibration is liable to occur and therefore the static rigidity is low. The aerostatic lead screw is useful for semiconductor fabrication and also effective in positioning a table on which a sample is placed in a biomicroscope. This study relates to a drunkenness analysis of the aerostatic lead screw. The drunkenness of a contact-type lead screw represented by the ball screw is generally transferred directly from the male screw to the female screw. In the aerostatic lead screw, the drunkenness based on machining accuracy error of each screw flank is not directly transferred onto the female screw and is instead averaged out by balancing of load capacities among each screw flank, so that the enhanced accuracy in positioning lead screws is expected. In this paper, a balance of the load capacity of each screw flank was computed using the aerostatic guidance theory, so as to carry out a drunkenness analysis. It is found that the balancing effect plays the vital role in improvement on drunkenness of an aerostatic lead screw used in this study.

scholarly journals Pseudodynamic Testing of Buildings Retrofitted with External Steel Reinforced Concrete Frames to Increase Lateral Strength for Earthquake Damage Prevention

2020 ◽  
Vol 2020 ◽  
pp. 1-21
Author(s):  
Ju-Seong Jung ◽  
Kang-Seok Lee
Keyword(s):  
Reinforced Concrete ◽  
Cyclic Loading ◽  
Load Capacity ◽  
Earthquake Damage ◽  
Seismic Retrofitting ◽  
Rc Frame ◽  
Control Specimen ◽  
Rc Buildings ◽  
Loading Test ◽  
Steel Reinforced Concrete

In this study, a new technique for seismic retrofitting via the attachment of an “external steel reinforced concrete frame” (ESRCF) system was developed to strengthen medium-to-low-rise reinforced concrete (RC) buildings. Two methods (bolting and welding) were developed to connect existing RC frames and external strengthening elements; these methods are technically and practically suited to various construction conditions. The retrofitting method developed in this study can be used to perform seismic strengthening construction, while residents continue to live within the building. The method is categorized as a “strength design approach” implemented via retrofitting, allowing the lateral ultimate load capacity of RC buildings, whose failure mode is shear, to be increased easily. Test specimens were designed based on an existing RC building in Korea lacking seismic data and then strengthened using the ESRCF system. Pseudodynamic and cyclic loading tests were conducted to verify the effects of seismic retrofitting. In total, four RC frame specimens were prepared: one nonstrengthened control specimen for the cyclic loading test, one nonstrengthened control specimen, one specimen strengthened with a welded ESRCF system, and one specimen strengthened with a bolted ESRCF system for the pseudodynamic test. The earthquake response behavior with use of the proposed method, in terms of the maximum response strength, response displacement, and degree of earthquake damage, is compared with a control RC frame. The test results indicated that both the bolting and welding methods used for connecting the existing RC frame to the ESRCF effectively increased the lateral ultimate strength, resulting in reduced response displacement of building structures under large-scale earthquake conditions.

Design of the Ball Screw Mechanism for Optimal Efficiency

1989 ◽  
Author(s):  
M.-C. Lin ◽  
S. A. Velinsky ◽  
B. Ravani
Keyword(s):  
Closed Form ◽  
Static Analysis ◽  
Load Capacity ◽  
Equations Of Motion ◽  
Closed Form Solution ◽  
Form Solution ◽  
Ball Screw ◽  
Exact Theory ◽  
Screw Mechanism ◽  
Extensive Computation

Abstract This paper develops theories for evaluating the efficiency of the ball screw mechanism and additionally, for designing this mechanism. Initially, a quasi-static analysis, which is similar to that of the early work in this area, is employed to evaluate efficiency. Dynamic forces, which are neglected by the quasi-static analysis, will have an effect on efficiency. Thus, an exact theory based on the simultaneous solution of both the Newton-Euler equations of motion and the relevant kinematic equations is employed to determine mechanism efficiency, as well as the steady-state motion of all components within the ball screw. However, the development of design methods based on this exact theory is difficult due to the extensive computation necessary and thus, an approximate closed-form representation, that still accounts for the ball screw dynamics, is derived. The validity of this closed-form solution is proven and it is then used in developing an optimum design methodology for the ball screw mechanism based on efficiency. Additionally, the self-braking condition is examined, as are load capacity considerations.

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