scholarly journals Determination of the Stress Increase of the Unbonded Tendon in a Continuous Concrete Beam at Ultimate Capacity Using Nonlinear Analysis

2021 ◽  
Vol 64 (1) ◽  
pp. 109-128
Author(s):  
Tarja Nakari ◽  
Anssi Laaksonen
Keyword(s):  
Nonlinear Analysis ◽  
Cross Sections ◽  
Concrete Beam ◽  
Continuous Beam ◽  
Ultimate Capacity ◽  
Moment Capacity ◽  
Stress Increase ◽  
Moment Redistribution ◽  
The Moment ◽  
Post Tensioned

Abstract Predicting the stress increase of an unbonded tendon in a post-tensioned continuous concrete beam at ultimate capacity is more difficult than when bonded tendons are used. The failure mechanisms of the continuous beam are also different to that of the simple-span beam. The loading type, ductility of the support area and moment redistribution influence the behaviour of the continuous structures. In this research, the simplified nonlinear analysis was used for predicting the unbonded tendon stress increase at ultimate capacity in continuous two-span beams. The model is based on the moment-curvature relationships of the reinforced concrete cross-sections under different compressive forces and deformations of the continuous beam under loading. The results have been compared with the experimental results of recent studies found in the literature. In addition, 92 unbonded post-tensioned two-span beams with different reinforcements have been examined by using the model and compared to the results obtained from empirical equations from the literature. The results from the nonlinear analysis correspond well to the results from the other models up to the reinforcement ratio of 0.35. The calculated values of the maximum moment capacity at the centre support were close to the results from the test beams.

Feasibility of using reduced length superelastic shape memory alloy strands in post-tensioned steel beam–column connections

2018 ◽  
Vol 30 (2) ◽  
pp. 283-307 ◽  
Author(s):  
Md Arman Chowdhury ◽  
Ahmad Rahmzadeh ◽  
Saber Moradi ◽  
M Shahria Alam
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
High Strength ◽  
Absorption Capacity ◽  
Full Length ◽  
Steel Beam ◽  
Moment Capacity ◽  
Repair Costs ◽  
The Moment ◽  
Post Tensioned

Driven by a need to reduce repair costs and downtime in structures following a major earthquake, self-centering systems have been introduced. Post-tensioned high strength steel strands have shown promising results in providing self-centering capability in steel frames, where the beams are compressed to columns. This study aims at investigating the feasibility of using reduced length of steel and shape memory alloy strands in steel beam–column connections. Through finite element modeling, the study first evaluates the effect of using short-length regular post-tensioned strands in steel connections. The results show higher strength, stiffness, and energy dissipation capacity for connections with shorter length regular post-tensioned strands. The moment capacity and energy absorption capacity of a post-tensioned beam–column connection with one-third strand length were 105% and 114% higher than those of with full-length strands, respectively. However, residual drifts increased from 4 to 39 mm. To avoid loss in the re-centering capability of such connections due to yielding/failing of post-tensioned steel strands, the application of shape memory alloy and hybrid strands are proposed. The results show that shorter length shape memory alloy strands are effective in regaining self-centering and dissipating higher amount of energy compared to the full-length steel strands.

scholarly journals Lateral torsional buckling capacity of corroded steel beams: A parametric study

2021 ◽  
Vol 1201 (1) ◽  
pp. 012038
Author(s):  
G Kullashi ◽  
S C Siriwardane ◽  
M A Atteya
Keyword(s):  
Cross Sections ◽  
Parametric Study ◽  
Analytical Framework ◽  
Reduction Factor ◽  
Steel Beams ◽  
Uniform Corrosion ◽  
Lateral Torsional Buckling ◽  
Torsional Buckling ◽  
Moment Capacity ◽  
The Moment

Abstract Thickness reduction due to uniform corrosion increases the tendency of lateral torsional buckling (LTB) of open cross-sections and it reduces the moment capacity of the beam. The effect of the various corrosion cases on the LTB moment capacity (M b,rd) of the I-beams are investigated in this paper. An analytical framework for patch corroded I-beams is introduced to provide a guideline for simulating the nonlinear lateral torsional buckling behaviour of patch corroded simple beams. Hence the effect of different corrosion scenarios to reduce the buckling reduction factor (η LT) is investigated by conducting a parametric study. Twelve different beam lengths were considered to obtain different non-dimensional slenderness ratios (λ LT) in this parametric study. The degraded buckling curves were obtained for each corrosion scenarios.

Flexural Resistance of Steel-Coconut Shell Concrete-Steel Composite Beam with Normal and J-Hook Shear Studs

2020 ◽  
Vol 12 (9) ◽  
Author(s):  
Lakshmi Thangasamy ◽  
◽  
Gunasekaran Kandasamy ◽  
Keyword(s):  
Concrete Strength ◽  
Steel Plates ◽  
Coconut Shell ◽  
Core Material ◽  
River Sand ◽  
Concrete Core ◽  
Conventional Concrete ◽  
Moment Capacity ◽  
The Moment ◽  
Core Concrete

Many researches on double skin sandwich having top and bottom steel plates and in between concrete core called as steel-concrete-steel (SCS) were carried out by them on this SCS type using with different materials. Yet, use of coconut shell concrete (CSC) as a core material on this SCS form construction and their results are very limited. Study investigated to use j-hook shear studs under flexure in the concept of steel-concrete-steel (SCS) in which the core concrete was CSC. To compare the results of CSC, the conventional concrete (CC) was also considered. To study the effect of quarry dust (QD) in its place of river sand (RS) was also taken. Hence four different mixes two without QD and two with QD both in CC and CSC was considered. The problem statement is to examine about partial and fully composite, moment capacity, deflection and ductility properties of CSC used SCS form of construction. Core concrete strength and the j-hook shear studs used are influences the moment carrying capacity of the SCS beams. Use of QD in its place of RS enhances the strength of concrete produced. Deflections predicted theoretically were compared with experimental results. The SCS beams showed good ductility behavior.

scholarly journals APPLICATION OF DOMAIN INTEGRATED DESIGN METHODOLOGY FOR BIO-INSPIRED DESIGN- A CASE STUDY OF SUTURE PIN DESIGN

2021 ◽  
Vol 1 ◽  
pp. 487-496
Author(s):  
Pavan Tejaswi Velivela ◽  
Nikita Letov ◽  
Yuan Liu ◽  
Yaoyao Fiona Zhao
Keyword(s):  
Cross Sections ◽  
Design Methodology ◽  
Reaction Force ◽  
Integrated Design ◽  
Total Deformation ◽  
Insertion Force ◽  
Force Reaction ◽  
The Moment ◽  
Work Done

AbstractThis paper investigates the design and development of bio-inspired suture pins that would reduce the insertion force and thereby reducing the pain in the patients. Inspired by kingfisher's beak and porcupine quills, the conceptual design of the suture pin is developed by using a unique ideation methodology that is proposed in this research. The methodology is named as Domain Integrated Design, which involves in classifying bio-inspired structures into various domains. There is little work done on such bio-inspired multifunctional aspect. In this research we have categorized the vast biological functionalities into domains namely, cellular structures, shapes, cross-sections, and surfaces. Multi-functional bio-inspired structures are designed by combining different domains. In this research, the hypothesis is verified by simulating the total deformation of tissue and the needle at the moment of puncture. The results show that the bio-inspired suture pin has a low deformation on the tissue at higher velocities at the puncture point and low deformation in its own structure when an axial force (reaction force) is applied to its tip. This makes the design stiff and thus require less force of insertion.

Elastic Waves Created During Tensile Fracture: The Phenomenon of a Second Fracture

1953 ◽  
Vol 20 (1) ◽  
pp. 122-130
Author(s):  
Julius Miklowitz
Keyword(s):  
Cross Sections ◽  
Tensile Tests ◽  
Analog Computer ◽  
Tensile Fracture ◽  
Strain Waves ◽  
Unloading Wave ◽  
Second Fracture ◽  
Wave Compression ◽  
Initial Fracture ◽  
The Moment

Abstract In some tensile tests with brittle materials, it was noted that fractures were produced at two different cross sections of the specimen when the rupture load was reached. The phenomenon of the second fracture prompted the present investigation. It is believed that the second fracture is caused by the destructive action of the elastic strain waves created during the first of the two fractures. The analytical and experimental work carried out was focused on describing the character of these waves. Consideration of the mechanics involved reduces the problem to that of a vibrating cantilever beam with time-dependent boundary conditions. Two types of waves are shown to exist. The first is a longitudinal unloading wave (compression). The other is a group of flexural strain waves caused by the moment that develops at the initial fracture section. The methods of operational mathematics and the electric-analog computer have been employed in the analytical study.

scholarly journals NONLINEAR ANALYSIS OF STATICALLY INDETERMINATE WOODEN STRUCTURES AND OPTIMIZATION OF CROSS SECTION DIMENSIONS OF DOME RIBS

2018 ◽  
Vol 14 (4) ◽  
pp. 130-139 ◽  
Author(s):  
Konstantin P. Pyatikrestovsky ◽  
Boris S. Sokolov
Keyword(s):  
Nonlinear Analysis ◽  
Cross Section ◽  
Cross Sections ◽  
Frame Analysis ◽  
Significant Part ◽  
Design Recommendations ◽  
Longitudinal Ribs ◽  
Non Linear ◽  
Wooden Structures

The analysis of the behaviour of natural structures of laminated wood domes and the numerous preliminary calculations have shown the possibility of saving materials by reducing the height of cross sections of meridional ribs. This is especially effective when you include in design of skins, performing a role of building shell, the collaboration with frame elements (annular and longitudinal ribs). Multiple static indeterminacy of such structure allows its non-linear work and the redistribution of forces under nonuniform loads. At the same ime, the skin carries a significant part of the forces appearing in the shell and the ribs are underloaded. The tress-strain states of all elements are investigated. For the frame analysis the calculation is performed by the method of integral module that allows controlling strength resistance of a structure at any moment of its operation. The design recommendations for section dimensions of a shell are developed.

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