Jointed Plane Research Articles

Study on interior beam–column joint sub-assemblage under bi-directional loading using finite element analysis

Purpose The purpose of this paper is to study the shearing performance under bi-directional loading of an interior beam–column joint (BCJ) sub-assemblage using the finite element analysis (FEA) tool (midas fea), validated in this research. Design/methodology/approach The BCJ can be defined as an essential part of the column that transfers the forces at the ends of the members connected to it. The members of the rigid jointed plane frame resist external forces by developing twisting moment, bending moment, axial force and shear force in the frame members. On the type of joints, the response to the action of lateral loads depends on reinforced concrete (RC) framed structures. The joint is considered rigid if the angle between the members remains unchanged during the structural deformation. This work examined the shear deformation, load displacement and strength of a non-seismically detailed internal concentric RC joint using non-linear FEA. The bi-directional loading imposes the oblique compression zone on one joint corner. This joint core’s oblique compression strut mechanism differs significantly from that under unidirectional loading. The numerical results are compared with experimental results in this study, with the data published in the literature. Findings Numerical analysis results show that, in the comparative study of numerical and experimental values, the FEA tool predicts the behaviour of the RC BCJ well. The discrepancy between the experimental and numerical results amounts to 6 to 12% end displacement of the beam, 7% resultant joint shear force, 4.23% column bar strain and 0.70% hoop strain. Originality/value The current code of practice describes the joint sub-assemblage behaviour along the single axis individually. In the non-orthogonal system, the superposition of the two axes for joint space results in overlapping the stresses and, hence, the formation of the oblique strut. This may result in a reduction in the joint capacity under bi-directional loading. The behaviour must be explored in depth, and an attempt is made for further exploration.

Modeling and analysis of a pin jointed plane frame using Biomimicked structural elements

Biomimicry can be termed as the concept that involves the imitation of models, systems and elements of the nature to solve complex human problems. When compared to the conventional techniques, it is an efficient, innovative and sustainable way and thus has scope in future. The various levels in biomimicry are utilized in the construction of the structures inspired from the nature thus paving way to innovation and sustainability. Various information can be learnt from nature when it comes to solving our challenges in a sustainable way. Nature builds to shape, because shape is cost effective and it minimizes the expenditure on materials while maximizing the effectiveness to achieve the desired functions. In this study the analysis of the conventional pin jointed plane frame is done first using STAAD. Pro to identify the compression and tension members in the frame. The various conventional frame models are modelled and analyzed. The finite element analysis is done using ANSYS 2020R2. A conventional pin jointed plane frame of height 4 m, bay width 4 m and strut length of 5.66 m were analyzed to know its member properties. A conventional pin jointed frame with horizontal springs provided at both the sides of the frame was modelled and analyzed. The optimized mimicked members are assembled to form the mimicked frame and analyzed. The various parameters such as total deformation, directional deformation, normal stress, equivalent stress, maximum principal stress and minimum principal stress were compared for the pin jointed plane frames. The present study helps in the reduction of material usage and self-weight of elements thus resulting in a sustainable and efficient structure

Measurement of Decay Time Constant of Shielding Current in ITER-TF Joint Samples

Joint sample tests have been carried out as a qualification test for ITER Toroidal Field (TF) coils. The joint sample comprises two short TF conductors that have “twin-box” joint terminals at both ends. The lower joint is a testing part that is a full size joint of the TF coils. Hall probes are attached on the lower joint box at around the center of the external field coil of the test facility. The magnetic field induced by shielding currents in the joint can be estimated from the difference between the measured magnetic field strength and the magnetic field generated by the external field coil. The magnetic field by the shielding currents during shut-off of the external field coil from -1.0 T is evaluated for six samples. The decay time constants of the shielding currents are gradually elongated with decrease of the shielding currents in all the samples. In comparison with simulation results, it is considered that the main shielding current flows in superconducting cables in the two conductors with crossing the jointed plane and that the joint resistance is decreased at low total current.

Numerical modelling of blast-induced fractures in coal masses under high in-situ stresses

Borehole blasting is a technique widely applied to form fracture networks in coal masses. There are many original cracks in coal masses, such as bedding planes and cleat planes. Coal masses are also subjected to high in-situ stress deep underground. However, the effects of pre-existing cracks and in-situ stress on blast-induced fractures are not well understood. In this paper, the isotropic and kinematic hardening plasticity model considering compression and tensile failure is introduced to numerical models, and the contact interface is used to simulate the effect of jointed planes on coal-mass blasting. The effects of jointed plane, constant in-situ stress and lateral pressure coefficient on blast-induced cracks are explored, and the relative peak displacement (Δup) of jointed planes is considered as the basis for determining jointed plane failure. The results indicate that blast-induced cracks tend to expand along jointed planes in the coal mass; the in-situ stress enhances the compression effect and weakens the tension effect in the radial direction of the borehole; and the jointed plane failure zone in coal masses decreases with increasing in-situ stress. The lateral pressure coefficient also has a distinctive influence on blast-induced crack expansion.

Study of Shear Capacity of Jointed Rock Mass with Prestressed Anchor Bolt

Rock mass failure caused by jointed plane is the common disaster in geotechnical engineering. Research on shearing property of jointed rock mass with prestressed anchor bolt and its mechanical property is an aspect for the stability analysis of rock slope and tunnel. This paper studies the stress and deformation of bolt and jointed plane, as well as anchored body and rock mass during shearing by indoor model testing and theoretical analysis. The shearing strength and mechanical property of anchored jointed plane have been systematically studied, and the additional force caused by deformation of prestressed anchor bolt and jointed rock mass during the shearing has been proposed and verified. The anchorage interaction between rock mass and bolt is revealed.

A Study on Loading and Unloading Criteria and Strength Criterion of Unloading Food Mass

Based on basic deformation mechanism of jointed food mass, combining loading and unloading concept of classical mechanics, we explored the practicability of classical loading and unloading criterion and proposed the principle is not suitable for deformation mechanism of jointed food mass, initially put forward the loading and unloading criterion for jointed food mass. We conducted the model test of unloading food mass. In order to reflect the jointed food mass properties, embedded-film technique is applied in model test. Food mass under unloading condition showed compression-shear failure. When the angle between jointed plane and unloading direction is 40° or 60°, the failure will be along the jointed plane. Finally, we proposed the unloading strength criterion.

Thermal stress analysis of jointed plane in concrete pavements

Daily changing temperature causes significant thermal stress and deformations in concrete pavement with laterally fixed planes. These stresses are important parameters included in dimensioning of pavement and are significantly depended on thermal difference of plane (i.e. difference in temperature between upper and lower surface plane). In this article, thermal stresses were analysed in relationship to different diameters of dowel bars. First of all, the studies were focused on stresses distributed around the dowel bar and caused by thermal differences. The analyses were carried out using finite element method (FEM). Based on this model, temperature distribution in concrete slab was studied and next calculations for different types of dowel joints and various climatic conditions in Central Europe (Poland) were performed. Results showed that application of dowel bars with small diameters increases stresses around them. Especially harmful is concentration of stretching stresses in concrete on two sides of dowel bar. These stresses can exceed permissible values in the case of incidental strong thermal differences. The obtained results can be helpful in design of new concrete pavements and assessment of their load in countries with big temperature amplitudes.

SMART ANALYSIS OF MOST BUILD MULTISTORIED RCC BUILDING OF GULBARGA REGION

As a part work of searching the easy and simple way of structural analysis and design to the practical life line structure (Commonly permitted and constructed Reinforced cement concrete (RCC) Multistoried building structure in Gulbarga Region of Karnataka state), this work is carried out which is a breakthrough as it gives easy guide for analysis to many technocrats who are unconfident in practical structural design of day to day encountered structure. Extensive information of RCC multistoried building structures which are permitted hence got constructed in Hyderabad Karnataka is gathered, which is found as Ground plus three storied RCC Commercial building having regular frame layout. The different methods of structural analysis available in civil engineering and structural engineering domain are gathered by which the structure under consideration can be analyzed. From these different methods and procedures after careful study a simple method is picked so that it should be relatively easy and should not consume huge time. To be easily understood by unconfident technocrat of this region. Since the structure under consideration was having rigid jointed plane frame, and the degree of accuracy required in analysis for such a building is not very high, the Substitute frame method has been zeroed and used. The method is suitable even for hand computations for non sway structures.

An integrated assessment of continuously reinforced and jointed plane concrete pavements

PurposeThis paper aims to provide an integrated framework of life cycle assessment (LCA) and life cycle cost analysis (LCCA) for assessing alternative technologies, processes, and/or activities, with focus on concrete pavements.Design/methodology/approachLCA and LCCA are used to evaluate environmental and economic impacts of substituting different percentages of fly ash and slag into continuously reinforced concrete pavement (CRCP) and jointed plane concrete pavement (JPCP). Impacts are determined over different life cycle phases.FindingsAn LCA of the extraction phase indicated that JPCP pavement had 33‐62 percent less emissions than CRCP pavements, when only steel consumption was considered. When cement was considered, JPCP pavement had almost 40 percent greater emissions then CRCP for all mix types. An LCCA showed that over the entire life cycle phases studied, CRCP pavements had about 46 percent more costs than JPCP. However, when only maintenance costs were considered, CRCP pavement cost 80 percent less to maintain than JPCP over the studied period of 35 years.Originality/valueThe study is a step towards using an integrated framework to evaluate the performance of different materials and technology. The same framework could be conducted for different kinds of asphalt pavements and concrete pavements, as well as other infrastructure that makes up the built environment, with the goal of making decisions that take into account design considerations, environmental impacts, and cost effectiveness.

TOWARDS DEEP AND SIMPLE UNDERSTANDING OF THE TRANSCENDENTAL EIGENPROBLEM OF STRUCTURAL VIBRATIONS

When using exact methods for undamped free vibration problems the generalized linear eigenvalue problem ( K−ω 2 M) D=0 of approximate methods, e.g., finite elements, is replaced by the transcendental eigenvalue problem K (ω) D=0. Here ω is the circular frequency; D is the displacement amplitude vector; M and K are the mass and static stiffness matrices; and K (ω) is the dynamic stiffness matrix, with coefficients which include trigonometric and hyperbolic functions involving ω and mass because elements (for example, bars or beams) are analyzed exactly by solving their governing differential equations. The natural frequencies of this transcendental eigenvalue problem are generally found by the Wittrick–Williams algorithm which gives the number of natural frequencies below ω t , a trial value of ω, as ∑ J m + s{ K (ω t )} where s {} denotes the readily computed sign count property of K (ω) and the summation is over the clamped–clamped natural frequencies of all elements of the structure. Understanding the alternative solution forms of the transcendental eigenvalue problem is important both to accelerate convergence to natural frequencies, e.g., by plotting ∣ K (ω)∣, and to improve the mode calculations, which lack the complete reliability of natural frequencies obtained by using the Wittrick–Williams algorithm. The three solution forms are: ∣ K (ω)∣= 0; D= 0 with ∣ K (ω)∣ →∞; and ∣ K (ω)∣≠0 with D≠ 0. The literature covers the first two forms thoroughly but the third form has been almost totally ignored. Therefore, it is now examined thoroughly, principally by analytical studies of simple bar structures and also by confirmatory numerical results for a rigidly jointed plane frame. Although structures are unlikely to have exactly the properties giving this form, it needs to be understood, particularly because ill-conditioning can occur for structures approximating those for which it occurs.

Efficient parallel solution of structural eigenvalue problems

An efficient parallelisation of an existing sequential method for obtaining the eigenvalues of a structure by an exact analytical procedure is presented. Results are given which illustrate finding the undamped natural frequencies of a rigidly jointed plane frame, but the method is also applicable to buckling problems and to other types of structure. The parallel method is suited to both distributed and shared-memory parallel machines. It seeks to equate the workload of each processor (node) by initially sharing out the work and by subsequently passing work from working nodes to idle nodes. Experimental runs on an nCUBE2 computer show that reasonably high levels of efficiency are possible.

Effect of horizontal diaphragm flexibility on the P-delta analysis

This paper investigates the importance of including the effects of the flexibility of the horizontal diaphragms when using the P-delta method of analysis, especially when considering the loads applied to intermediate frames on trusses that are not part of the lateral force resisting system. Analyses were conducted for structural systems with a variable number of stories, number of bays and diaphragm stiffnesses and supported by rigid jointed plane frames or vertical trusses.

A modified elastic-plastic analysis including graphical processing of plane framed structures

A stiffness-based modified approach is developed for the elastic-plastic analysis of rigid jointed plane frames by tracing the response of the frame under increasing loads from the beginning to collapse by a stepwise elastic analysis. An important feature of the suggested approach is that it involves treating each span, which may or may not have plastic hinges and which may be subjected to concentrated and/or uniform loads, as an undivided member with six degrees of freedom. Each aspect of the analysis is translated into a C language instruction with emphasis on the development of graphics processors. Rectangular and non-rectangular frame examples are included to demonstrate the capabilities of the suggested approach.

Transmission of Wave Energy through an Imperfectly Bonded Interface. 2nd Report. P Wave.

Propagation of P wave (longitudinal wave) in layered half space is considered. Reflection and transmission coefficients at an imperfectly bonded interface are analyzed. The bonding strength at the interface is assumed as Joint Coefficient Dx and Dy, which represent tangential and normal direction joints of the jointed plane, respectively. The energy of reflected and transmitted wave is very sensitive, and resonance of the plate occurs for short wave lengths. It is more remarkable for small incident angles. When the bonding strength is strong, reflection and transmission coefficients show very complex variations. The relation between the two coefficients and bonding strength is also discussed.

Direct versus indirect methods in structural optimization

Mathematical programming methods are among the most powerful optimization techniques. These techniques may be separated into direct and indirect methods. Of the direct methods of attack on general nonlinear inequality constrained problems, the largest class is the method of feasible directions. Of the indirect methods, the interior penalty function appears to be the most reliable one while the variable metric method seems to be an extremely powerful algorithm. This paper presents a comparison between the results obtained using Zoutendijk's method of feasible directions and the method of interior penalty function coupled with the variable metric method as a minimizing algorithm. A considerable improvement in convergence has been achieved by considering each push-off factor as a linear function of the corresponding active constraint. A comparison of the half-step vs full-step search procedure is presented. Also a comparison between the use of either the normalized or the non-normalized gradients is illustrated. A discussion of the linear vs quadratic interpolations of a constraint function in search for a bound point is presented. An initial step length based on a present decrement of objective function is used. The two algorithms are demonstrated with elastic design of a 25-bar space tower, a 3-bay single-storey frame and a double-bay double-storey rigid jointed plane frame. Data on the differences in the optimal designs obtained from different starting points are reported.

Concise equations and program for exact eigensolutions of plane frames including member shear

A unified notation is adopted to present concise member equations for a Timoshenko beam-column and a static beam-column with finite shear stiffness. The Fortran coding necessary to incorporate these equations into a previously published computer program is given. The resulting program enables any number of exact natural frequencies or elastic critical buckling loads of rigidly jointed plane frames to be calculated using an algorithm which ensures that none can be missed. The corresponding mode shapes can then be retrieved by a simple technique which offers improved accuracy over more established methods. The program contains approximately 250 Fortran statements and has been designed to minimise core store requirements at the expense of computation time. The use of the program as a ‘black box’ is fully explained with illustrative examples.

Exact Buckling and Frequency Calculations Surveyed

The usefulness and simplicity of an existing stiffness matrix method is emphasized by presenting it without its relatively complex proofs, and with simple examples. The method ensures that no natural frequencies are missed in undamped free vibration problems, and that no critical load factors are missed in buckling problems. This is maintained even when using the ‘exact’ member equations obtained by solving the appropriate differential equations. The method applies to all structures for which ‘exact’ member equations exist. The published applications are surveyed. They include rigidly jointed plane frames, space frames, and prismatic assemblies of flat or curved plates which are isotropic or anisotropic, and subjected to in‐plane normal or shear stresses. They also cover efficient multi‐level substructuring, design instead of analysis, damping, forced vibrations, elastic‐plastic collapse and programs for large computers, small computers, and programmable pocket calculators.

Application of methods of feasible directions to structural optimization problems

A general approach to structural optimization which has received much attention in recent years is that of using mathematical programming (numerical search) techniques. These techniques may be separated into direct and indirect methods. Of the direct methods of attack on general nonlinear inequality constrained problems, the largest class is called methods of feasible directions. This paper presents the application fo Zoutendijk's method of feasible directions [5] to structural optimization problems. The algorithm requires the analytic gradient of the objective function and the constraint functions which are active at a given stage in the design process. A considerable improvement in convergence has been achieved by considering each pushoff factor as a linear function of the corresponding active constraint. A comparison of the half-step versus full-step search procedure is presented. An initial step length based on a present decrement of objective function is used. A discussion of the linear versus quadratic interpolations of a constraint function in search for a bound point is presented. The algorithm is demonstrated with elastic design of a 25-bar space tower, a 3-bay single storey and a double bay double storey rigid jointed plane frames. Data on the differences in the optimum designs obtained from different starting points is reported.

A compact method for computing the eigenvalues and eigenvectors of plane frames

Two Fortran computer programs are presented which calculate the eigenvalues and eigenvectors of rigidly jointed plane frames. The eigenvalues are natural frequencies and critical load factors in vibration and buckling problems, respectively, while the eigenvectors are the corresponding mode shapes. The theory is based on the stiffness method of analysis and uses classical (exact) member equations together with an algorithm which ensures that the required eigenvalues are found with certainty. The corresponding eigenvectors are then retrieved by a simple technique which offers improved accuracy over more established methods. The programming style is specifically aimed towards minicomputer application and this is illustrated by annotated listings of the programs, each of which contains just over two hundred Fortran statements. The use of the programs as ‘black boxes’ is fully explained with illustrative examples.

Compact computation of natural frequencies and buckling loads for plane frames

AbstractExisting theory is assembled to give a method which needs only the core of a mini‐computer to calculate the eigenvalues of large rigidly jointed plane frames with certainty, the eigenvalues being natural frequencies and critical load factors in free vibration and buckling problems, respectively. The method is illustrated by annotated listings of vibration and buckling programs, each involving under two hundred Fortran statements and with low number storage requirements (see Table I). The use of the programs as ‘black boxes’ is fully explained, with illustrative examples.The member theory used is the ‘exact’ classical Bernoulli‐Euler uniform member theory. Possible applications include: evaluation of answers from approximate methods; calculation of critical loads for substitution in the modified Merchant‐Rankine formula to estimate collapse loads of frames; and calculation of shifts in natural frequencies caused by structural damage, in connection with structural integrity monitoring of inaccessible structures.