scholarly journals Tree Pulling Tests of Large Shade Trees in the Genus Acer

2008 ◽  
Vol 34 (2) ◽  
pp. 101-109
Author(s):  
Brian Kane ◽  
Peggi Clouston
Keyword(s):  
Maximum Stress ◽  
Bending Moment ◽  
Maximum Load ◽  
Shade Trees ◽  
Bending Moments ◽  
Morphometric Data ◽  
Moment Stress ◽  
Cross Sectional ◽  
Data Prediction ◽  
Wood Strength

Shade trees provide many benefits but can cause damage if they fail. Despite the potential for costly litigation that sometimes arises when damage occurs, there are no investigations of bending moments and stresses involved in failure of shade trees. Twenty-four shade trees of three species in the genus Acer were pulled to failure at a suburban property in Massachusetts, U.S. The maximum load and distance to failure were used to calculate maximum bending moment; stress at the point of failure was calculated from bending moment and stem cross-sectional dimensions. No trees uprooted, and failures were categorized as either stem at a lateral branch(es) or the attachment of codominant stems. Failures of codominant stems required one-half of the stress of stem failures. Similarly, failures of codominant stems occurred at only 45% of wood strength, whereas stem failures occurred at 79% of wood strength. Prediction of maximum bending moment from tree morphometric data was more reliable than prediction of maximum stress from tree morphometric data. Prediction of maximum bending moment and stress was more reliable for stem failures than codominant failures. Results are compared with similar tests on conifers. Implications of findings are discussed with respect to risk assessment of shade trees.

Investigation of Smooth Pipe Bends Under the Effect of In-Plane Bending

2017 ◽  
Author(s):  
Diana Abdulhameed ◽  
Michael Martens ◽  
J. J. Roger Cheng ◽  
Samer Adeeb
Keyword(s):  
High Stress ◽  
Circular Cross Section ◽  
Bending Moment ◽  
Bend Angle ◽  
Bending Moments ◽  
Bend Radius ◽  
Pipe Bend ◽  
Cross Sectional ◽  
Smooth Pipe ◽  
Plane Bending

Pipe bends are frequently used to change the direction in pipeline systems and they are considered one of the critical components as well. Bending moments acting on the pipe bends result from the surrounding environment, such as thermal expansions, soil deformations, and external loads. As a result of these bending moments, the initially circular cross-section of the pipe bend deforms into an oval shape. This consequently changes the pipe bend’s flexibility leading to higher stresses compared to straight pipes. Past studies considered the case of a closing in-plane bending moment on 90-degree pipe bends and proposed factors that account for the increased flexibility and high-stress levels. These factors are currently presented in the design codes and known as the flexibility and stress intensification factors (SIF). This paper covers the behaviour of an initially circular cross-sectional smooth pipe bend of uniform thickness subjected to in-plane opening/closing bending moment. ABAQUS FEA software is used in this study to model pipe bends with different nominal pipe sizes, bend angles, and various bend radius to cross-sectional pipe radius ratios. A comparison between the CSA-Z662 code and the FEA results is conducted to investigate the applicability of the currently used SIF factor presented in the design code for different loading cases. The study showed that the in-plane bending moment direction acting on the pipe has a significant effect on the stress distribution and the flexibility of the pipe bend. The variation of bend angle and bend radius showed that it affects the maximum stress drastically and should be considered as a parameter in the flexibility and SIF factors. Moreover, the CSA results are found to be un-conservative in some cases depending on the bend angle and direction of the applied bending moment.

scholarly journals Analisis Numerik Kuat Lentur Balok Support Beam Curve Tile Beton Semi Pracetak Dengan Variasi Panjang Bentangan

2020 ◽  
Vol 8 (2) ◽  
pp. 61-69
Author(s):  
Yoga Ornando ◽  
Ismeddiyanto ◽  
Iskandar Romey Sitompul
Keyword(s):  
Precast Concrete ◽  
Bending Moment ◽  
Maximum Load ◽  
Crack Pattern ◽  
Beam Length ◽  
Pure Bending ◽  
Element Analysis ◽  
Cross Sectional ◽  
Cross Sectional Dimension ◽  
The Cross

Semi precast slab is a combination of precast concrete which consist of the support beam and curve tile with the cast in place concrete. During the working process, support beam will support the entire load until the slab becomes solid. The study aims to identify the effect of using variations of support beam length towards deflection-load relationship, moment-curvature, crack pattern and cross-sectional dimensions caused by pure bending moments with the same maximum load. The variations of the support beam length are L = 3000 mm, L = 4000 mm, L = 5000 mm and L = 6000 mm which can affect the cross-sectional dimensions of the support beam. The method used in this study was the numerical method by using Abaqus 6.14 CAE software. Abaqus is one of the finite element analysis (FEA) programs to model and analysis the elements of the structure. The loading applied was an axial load which has increased until the support beam failed. The numerical analysis results are the increase of cross section dimension as the increasing of support beam length. The cross-sectional dimension are 100 mm x 60 mm; 110 mm x 65 mm; 110 mm x 70 mm; and 115 mm x 75 mm. The maximum load (Pmaks) was relative same while the support beam length increased are 1,52 kN; 1,53 kN; 1,53 kN and 1,55 kN. The collapse pattern on the support beam was a pure bending crack at the most significant bending moment region. The crack pattern showed the crack on the pull side of the beam in the direction of the stirrups.Semi precast slab is a combination of precast concrete which consist of the support beam and curve tile with the cast in place concrete. During the working process, support beam will support the entire load until the slab becomes solid. The study aims to identify the effect of using variations of support beam length towards deflection-load relationship, moment-curvature, crack pattern and cross-sectional dimensions caused by pure bending moments with the same maximum load. The variations of the support beam length are L = 3000 mm, L = 4000 mm, L = 5000 mm and L = 6000 mm which can affect the cross-sectional dimensions of the support beam. The method used in this study was the numerical method by using Abaqus 6.14 CAE software. Abaqus is one of the finite element analysis (FEA) programs to model and analysis the elements of the structure. The loading applied was an axial load which has increased until the support beam failed. The numerical analysis results are the increase of cross section dimension as the increasing of support beam length. The cross-sectional dimension are 100 mm x 60 mm; 110 mm x 65 mm; 110 mm x 70 mm; and 115 mm x 75 mm. The maximum load (Pmaks) was relative same while the support beam length increased are 1,52 kN; 1,53 kN; 1,53 kN and 1,55 kN. The collapse pattern on the support beam was a pure bending crack at the most significant bending moment region. The crack pattern showed the crack on the pull side of the beam in the direction of the stirrups.

Combined Bending and Compression of a Pressurized Circular Cylindrical Membrane Column

1965 ◽  
Vol 87 (3) ◽  
pp. 372-378
Author(s):  
W. E. Jahsman
Keyword(s):  
Compressive Strength ◽  
Cross Section ◽  
Compressive Load ◽  
Circular Cross Section ◽  
Bending Moment ◽  
Maximum Load ◽  
Bending Moments ◽  
Lateral Deflection ◽  
The Cross

Load-lateral deflection curves are developed for a pressurized tube of circular cross section under combined bending and compression. The tube walls are assumed to have negligible compressive strength so that wrinkling develops if the stress tends to become negative. It is found that for a given bending moment, the load increases monotonically with deflection until a maximum is reached beyond which the load decreases with increasing deflection. An interaction curve of the maximum load versus bending moment shows that the presence of only a small amount of bending significantly decreases the maximum compressive load below the classical Euler load. Conversely, for bending moments which produce almost complete wrinkling of the cross section, only very small amounts of compressive load can be supported.

An in vitro Comparison of Two Replacement Techniques Utilizing Fascia Lata after Cranial Cruciate Ligament Transection in the Dog

1993 ◽  
Vol 06 (02) ◽  
pp. 85-92 ◽  
Author(s):  
G. L. Coetzee
Keyword(s):  
Femoral Condyle ◽  
Cruciate Ligament ◽  
Maximum Load ◽  
Fascia Lata ◽  
Patellar Ligament ◽  
Cross Sectional ◽  
Cranial Cruciate Ligament ◽  
Replacement Technique ◽  
Over The Top

SummaryThe immediate postoperative biomechanical properties of an “underand-over” cranial cruciate ligament (CCL) replacement technique consisting of fascia lata and the lateral onethird of the patellar ligament, were compared with that of a modified intra- and extracapsular “under-and-over-the-top” (UOTT) method. The right CCL in twelve adult dogs was dissected out and replaced with an autograft. The contralateral, intact CCL served as the control. In group A, the graft was secured to the lateral femoral condyle with a spiked washer and screw. In group B the intracapsular graft was secured to the lateral femoro-fabellar ligament, and the remainder to the patellar tendon. Both CCL replacement techniques exhibited a 2.0 ± 0.5 mm anterior drawer immediately after the operation. After skeletonization of the stifles, the length and cross-sectional area of the intact CCL and CCL substitutes were determined. Each bone-ligament unit was tested in linear tension to failure at a fixed distraction rate of 15 mm/s with the stifle in 120° flexion. Data was processed to obtain the corresponding material parameters (modulus, stress and strain in the linear loading region, and energy absorption to maximum load).The immediate postoperative structural and material properties of the “under-and-over” cranial cruciate ligament replacement technique with autogenous fascia lata, were compared to that of a modified intra- and extracapsular “under-and-over-the-top” (UOTT) method. The combined UOT T technique was slightly stronger (6%), but allowed 2.8 ± 0.9 mm more cranial tibial displacement at maximum linear force.

scholarly journals Near-Fault Seismic Response Analysis of Bridges Considering Girder Impact and Pier Size

Mathematics ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 704
Author(s):  
Wenjun An ◽  
Guquan Song ◽  
Shutong Chen
Keyword(s):  
Seismic Response ◽  
Bending Moment ◽  
Expansion Method ◽  
Response Analysis ◽  
Seismic Action ◽  
Transient Wave ◽  
Cross Sectional ◽  
Displacement Response ◽  
Near Fault ◽  
Continuous Girder Bridge

Given the influence of near-fault vertical seismic action, we established a girder-spring-damping-rod model of a double-span continuous girder bridge and used the transient wave function expansion method and indirect modal function method to calculate the seismic response of the bridge. We deduced the theoretical solution for the vertical and longitudinal contact force and displacement response of the bridge structure under the action of the near-fault vertical seismic excitation, and we analyzed the influence of the vertical separation of the bridge on the bending failure of the pier. Our results show that under the action of a near-fault vertical earthquake, pier-girder separation will significantly alter the bridge’s longitudinal displacement response, and that neglecting this separation may lead to the underestimation of the pier’s bending damage. Calculations of the bending moment at the bottom of the pier under different pier heights and cross-sectional diameters showed that the separation of the pier and the girder increases the bending moment at the pier’s base. Therefore, the reasonable design of the pier size and tensile support bearing in near-fault areas may help to reduce longitudinal damage to bridges.

Effect of Torsion on Collapse Bending Moment for 24-Inch Diameter Schedule 80 Pipes With Wall Thinning

2012 ◽  
Author(s):  
Kunio Hasegawa ◽  
Yinsheng Li ◽  
Bostjan Bezensek ◽  
Phuong Hoang
Keyword(s):  
Power Plants ◽  
Bending Moment ◽  
Combined Loading ◽  
Bending Moments ◽  
Compressive Stresses ◽  
Wall Thinning ◽  
Nominal Thickness ◽  
Calculation Results ◽  
Loading Modes ◽  
Local Wall Thinning

Piping items in power plants may experience combined bending and torsion moments during operation. Currently, there is a lack of guidance in the ASME B&PV Code Section XI for combined loading modes including pressure, torsion and bending. Finite element analyses were conducted for 24-inch diameter Schedule 80 pipes with local wall thinning subjected to tensile and compressive stresses. Plastic collapse bending moments were calculated under constant torsion moments. From the calculation results, it can be seen that collapse bending moment for pipes with local thinning subjected to tensile stress is smaller than that subjected to compressive stress. In addition, equivalent moment is defined as the root the sum of the squares of the torsion and bending moments. It is found that the equivalent moments can be approximated with the pure bending moments, when the wall thinning length is equal or less than 7.73R·t for the wall thinning depth of 75% of the nominal thickness, where R is the mean radius and t is the wall thickness of the pipe.

Geometrical Stiffness of Thin-Walled I-Beam Element Based on Rigid-Beam Assemblage Concept

2012 ◽  
Vol 28 (1) ◽  
pp. 97-106 ◽  
Author(s):  
J. D. Yau ◽  
S.-R. Kuo
Keyword(s):  
Stiffness Matrix ◽  
Virtual Work ◽  
Bending Moment ◽  
Beam Element ◽  
Narrow Beam ◽  
Cross Sectional ◽  
Geometric Stiffness ◽  
Buckling Behavior ◽  
Post Buckling ◽  
Thin Walled

ABSTRACTUsing conventional virtual work method to derive geometric stiffness of a thin-walled beam element, researchers usually have to deal with nonlinear strains with high order terms and the induced moments caused by cross sectional stress results under rotations. To simplify the laborious procedure, this study decomposes an I-beam element into three narrow beam components in conjunction with geometrical hypothesis of rigid cross section. Then let us adopt Yanget al.'s simplified geometric stiffness matrix [kg]12×12of a rigid beam element as the basis of geometric stiffness of a narrow beam element. Finally, we can use rigid beam assemblage and stiffness transformation procedure to derivate the geometric stiffness matrix [kg]14×14of an I-beam element, in which two nodal warping deformations are included. From the derived [kg]14×14matrix, it can take into account the nature of various rotational moments, such as semi-tangential (ST) property for St. Venant torque and quasi-tangential (QT) property for both bending moment and warping torque. The applicability of the proposed [kg]14×14matrix to buckling problem and geometric nonlinear analysis of loaded I-shaped beam structures will be verified and compared with the results presented in existing literatures. Moreover, the post-buckling behavior of a centrally-load web-tapered I-beam with warping restraints will be investigated as well.

scholarly journals Influence of stirrup spacing on shear resistance and deformation of reinforced concrete beams

2018 ◽  
Vol 7 (1) ◽  
pp. 126
Author(s):  
Latha M S ◽  
Revanasiddappa M ◽  
Naveen Kumar B M
Keyword(s):  
Concrete Beam ◽  
Concrete Beams ◽  
Bending Moment ◽  
Maximum Load ◽  
Reinforced Concrete Beams ◽  
Test Results ◽  
Cement Concrete ◽  
Simply Supported ◽  
Reinforced Cement ◽  
Flexural Reinforcement

An experimental investigation was carried out to study shear carrying capacity and ultimate flexural moment of reinforced cement concrete beam. Two series of simply supported beams were prepared by varying diameter and spacing of shear and flexural reinforcement. Beams of cross section 230 mm X 300 mm and length of 2000 mm. During testing, maximum load, first crack load, deflection of beams were recorded. Test results indicated that decreasing shear spacing and decreasing its diameter resulted in decrease in deflection of beam and increase in bending moment and shear force of beam.

scholarly journals Experimental and Simulation Investigation of Bending Moment Effect on Hollow Columns of Multi-layers of Hybrid Materials

2019 ◽  
Vol 12 (1) ◽  
pp. 44-55
Author(s):  
Ayad A. Ramadhan
Keyword(s):  
Hybrid Materials ◽  
Volume Fraction ◽  
Load Capacity ◽  
Testing Machine ◽  
Bending Moment ◽  
Maximum Load ◽  
Experimental Procedure ◽  
Bending Load ◽  
Alumina Composite ◽  
Moment Effect

This paper presented the effect of bending on multi-layer of hollow columns of Hybrid materials (Carbon-Glass /epoxy-Alumina) composite this effect occurred and volume fraction of fibers. An experimental procedure was developed to study the performance of these effects under bending load using a hydraulic bending device type (MATEST. SRL) testing machine. This study has three forms through the selection of columns hollows width to thickness (a/b) (0.5, 1 and 2) with three types of layers of samples (2,4 and8) layers. The ultimate load of failure for each Hybrid/epoxy-Al2O3 had been determined and specified the optimum volume fraction (Vf) due to the effect of mixing 50% and 60% were low in the case for compared 55% volume fraction. To simulate this problem the researcher used Explicit Mesh for AUTODYN under ANSYS-15 software, it was found that maximum bending load for Hybrid/ Epoxy-Al2O3 Specimens, the maximum load of specimens increased with increasing number of layers from 2L to 8L. The results also identified that the maximum load capacity by 55% volume fraction and a/b=0.5 of all composite specimens was highest from the others types of (50% and 60%) volume fractions and (a/b=1 and a/b=2) .Also, the Increasing ratio of stress capacity for specimens have 4 to 2 layers (4/2)  and 8 to 4  (8/4) for experimental results have maximum value with increasing by 48.19%  and 46.84% at (Sp.4#8/Sp.2#4) and (Sp.8#6/Sp.4#6) respectively.

scholarly journals Mechanical Properties of Cervical Spinal Cord in Neonatal Piglet: In Vitro

2020 ◽  
pp. 1-3
Author(s):  
Anita Singh ◽  
Anita Singh ◽  
Rachel Magee ◽  
Sriram Balasubramanian
Keyword(s):  
Spinal Cord ◽  
Maximum Stress ◽  
Cervical Spinal Cord ◽  
Tensile Loading ◽  
Maximum Load ◽  
Spinal Cord Tissue ◽  
Prevention Strategies ◽  
Biomechanical Behavior ◽  
Injury Mechanisms

The response of neonatal spinal cord tissue to tensile loading is not well-studied. In this study, isolated fresh neonatal cervical spinal cord samples, obtained from twelve 2-4 days old piglets, were tested in uniaxial tension at a rate of 500 mm/min until failure. Maximum load, maximum stress, percentage strain at maximum stress and modulus of elasticity were reported to be 14.6±3.4 N, 0.34±0.11 MPa, 29.3±5.4% and 1.52±0.8 MPa, respectively. These data can help understand the biomechanical behavior of the spinal cord in neonates and can be further used in computational modeling to understand injury mechanisms better and help develop injury prevention strategies.

Sign in / Sign up

Export Citation Format

Share Document