Truss Type Research Articles

Analysis Of Steel-Rcc Composite Deck Bridge

: In the literature, provisions for analysis and design of steel-RCC composite deck type truss and cable-stayed bridges do not exist. A composite deck type truss bridge model is analyzed using STAAD Pro V8i software and a model with the same dimensions is tested in the laboratory. The experimental test results are used to validate the STAAD analysis results.
 Bottom chord strain and mid-span deflection of the composite bridge model as found from the STAAD analysis and the laboratory experiment closely tally with each other. This validates the standard STAAD analysis results. However, in the top chord member, due to shrinkage cracks in the deck slab concrete, the experimentally recorded strain is higher by about 100% than the STAAD analysis result. 
 Shear force in studs is considerably large near supports and joints as compared to the midsection. Therefore, the design of shear studs may be carried out based on the shear forces in the studs found from the STAAD analysis. 
 Thus it is recommended that STAAD or any other standard finite element analysis software can be used for analysis and design of the composite bridges.

Performance of modular hybrid cold-formed/tubular structural system

In recent years, modular construction has been used in low-to medium rise multi-story and even high-rise buildings. Pre-fabrication by off-site manufacture leads to faster and safer construction, improved quality, reduced resources and waste. The research activity summarized in this paper is carried out within the European project INNO3DJOINTS and it aims at developing innovative plug-and-play joints which enable modularity, faster construction and deconstruction. The developed modular construction system is hybrid, whereby tubular columns are combined with cold-formed lightweight steel profiles using plug-and-play connections to provide an efficient structural system. The influence of the type of floor system, the horizontal and vertical load-bearing systems and the type of truss on the structural performance are investigated. The results obtained from numerical analyses allowed optimizing the geometry of the examined hybrid modular system. To highlight its effectiveness and versatility, a case study building was used to compare the proposed hybrid system with other conventional structural solutions.

Shear Behavior of Concrete Encased Steel Truss Composite Girders

In this study, experimental tests were performed to evaluate the shear performance of encased steel truss (EST) composite girders that can resist loads at construction and composite stages. Four full-scale EST composite girders were fabricated, where the truss type (Pratt truss and Warren truss) and presence of stirrups were set as main test variables. The test results showed that in specimens applied with the Pratt truss, horizontal shear cracking occurring along the interface between concrete and steel was the dominant failure mode. Based on the crack pattern and failure plane observed from the test, the horizontal shear strengths of the Pratt truss specimens were calculated, which provided conservative results. On the other hand, in the specimens with the Warren truss inside, the strengths of the specimens were governed by the shear failure occurring in the screw rod connecting the truss elements prior to the yielding of the diagonal member. The shear strengths of the Warren truss specimens calculated based on the shear failure of the screw rod were similar to that obtained from the test.

Research of Influence of Bed Joints Reinforcement On Strength of Masonry Shear Walls with Openings Made of Calcium Silicate Masonry Units

This article describes results from testing reinforced and unreinforced walls made of calcium silicate units and having openings of different shapes. Conducted tests mainly focused on determining the effect of used reinforcement on the cracking morphology and values of cracking and failure forces. Every wall was made of calcium silicate units with vertical hollows (group I acc. to PN–EN 1996-1-1:2013). Tests covered 12 walls with the following external dimensions l = 4.45 m, h = 2.45 m, t = 180 mm, which varied in shape and dimensions of openings. Steel trusses of EFZ 140 / Z 140 type (Z1 type) and plastic meshes (Z2 type) were used as reinforcement. Models were divided into six series with a difference in the opening shape and the reinforcement type. Openings in walls were marked with letters A. B, and C. The opening of A type was a single window opening with a length of 1.50 m and a height of 1.12 m. That series included two models with truss type reinforcement (HA-Z1 (Z1 type of reinforcement) and two models with plastic mesh reinforcement (HA-Z2 (Z2 type of reinforcement). The opening of B type was also a window opening of 1.12 m in height, but longer - 2.50 m. That series included two models with truss type reinforcement (HB-Z1 (Z1 type of reinforcement) and two models with plastic mesh reinforcement (HB-Z2 (Z2 type of reinforcement). The opening of C type combined the window opening of 1.50 m in length and 1.12 in height and a door opening of 1.0 m in width and 1.90 in height. As in case of series of A and B type openings, tests were also performed on HC-Z1 series (Z1 type of reinforcement) and HC-Z2 series (Z2 type of reinforcement). The results were compared with test results for unreinforced walls with openings, tested under the same initial conditions. Reinforcement ratio in all reinforced models was ρ=0.07 (>ρmin=0.05). Walls were tested at different values of precompression stress σc = 0.1; 1.5 or 0.75 N/mm2. A mechanism of cracking and destruction, and values of cracking and failure stresses were analysed.

Optimización de armaduras espaciales de acero utilizando algoritmos genéticos auto-adaptados: una primera aproximación

En las últimas décadas, la optimización estructural mediante metaheurísticas ganó acogida en la comunidad científica; sin embargo, para garantizar buenos resultados se requiere una correcta selección de los parámetros de la metaheurísticas. En este trabajo se propone un algoritmo genético multi-cromosoma auto-adaptado para optimizar armaduras de acero tridimensionales. Las variables de diseño corresponden a las secciones asignadas a cada elemento en la armadura. El objetivo es la minimización del peso de la armadura, considerando desplazamientos y esfuerzos máximos como restricciones. El algoritmo propuesto se aplicó a la optimización de dos armaduras, produciendo diseños que pesan hasta un 35% menos que el mejor diseño inicial y son valores comparables al resultado obtenidos en otros trabajos. No obstante, la adaptación de los parámetros permite mayor robustez cuando se desea optimizar diferentes tipos de armadura y evita las ejecuciones del algoritmo de optimización que son necesarias para la calibración de sus parámetros.

Wave propagation in two dimensional structures: An efficient solution method in time domain using exponential basis functions

In this paper, an efficient time domain formulation is proposed for computing time history dynamic responses of 2D structures, i.e. various types of trusses and frames. Unlike the methods using frequency domain, the proposed method employs the time weighted residual approach to solve the governing differential equations of the axial and flexural wave propagation problems, directly in time. Upon choosing the time step, the solution procedure begins with expressing the variation of axial and transverse displacement components, through the member’s length, as the summations of Fourier exponential basis functions in each time step. The unknown coefficients of the next steps are computed by the implementation of recurrent relations obtained based on a pre-integration process. The equilibrium and necessary continuity conditions at the common nodes/joints of adjacent elements are also fulfilled by introducing an innovative concept utilizing source functions. The role of these source functions is to simulate the boundary effects of the axial and flexural waves propagating within the structural members, simultaneously. The efficiency of the method is demonstrated in the dynamic analysis of some samples of truss and framed structures in terms of accuracy and computational time.

A Comparative Study of the Hardness and Force Analysis Methods Used in Truss Optimization with Metaheuristic Algorithms and Under Dynamic Loading

Increasing the scarcity of raw materials, and the tendency to have light, efficient and inexpensive structures demonstrates the importance of structural optimization. In the optimization process, truss structures are of particular interest due to their high performance in the construction of a variety of structures. The conducted research in this area has produced a great variety of optimization methods, and the researchers emphasize the effectiveness of their proposed method. Considering this issue, summarize and perform a comparative study between optimization methods (classical methods and Metaheuristic Algorithms), analysis methods used in optimization (hardness and force methods) and different optimization loads (static and dynamic loads) is needed to choose the right method and use them more effectively. By examining the research that has been done, it can be noted that the optimizations mentioned above should be compared from many perspectives. In this paper, a decision was made to make a general comparison of the analysis methods used to trusses optimization to provide the basis for further comparisons. In the present study, 19 articles (from 2003 to 2017) have been studied and compared using Metaheuristic algorithms and under dynamic loading in order to compare two methods (hardness and force methods) of analysis in the field of optimization of trusses in terms of optimization types, target function types, constraints and plane and space truss types, and Large-scale trusses, and finally, these two analysis methods were further scrutinized to optimize the 10-member truss plane. The results of this research can be a useful aid for optimization researchers to identify the gaps and deficiencies of truss optimization research.

Behaviour of a Space Inverted Triangular Steel Truss

Behaviour of the inverted triangular truss, which is widely used as a bridge girder, was investigated analytically and experimentally. Cold-formed square hollow cross-sections of steel grade S355J2H with dimensions 80 mm × 4 mm, 90 mm × 4 mm and 40 mm × 4 mm were selected for the top and bottom chords and bracing elements of the truss with 12.56 m span, correspondingly. Five FEM models were developed using software Dlubal RFEM. The main specific feature of the models is the difference in modelling of joint behaviour considering plastic behaviour and stiffness of truss connections. It was shown that the FE model of the truss where the members were modelled by the truss type finite elements and the joints modelled by the shell type ones allows predicting behaviour of the truss with precision of up to 3.9%. It was shown that precision of the suggested FEM model grows 4.36 to 4.62 times in comparison with the traditional FEM models where the members were modelled by the truss finite elements with the pinned and rigid joints in case of plastic joint behaviour. Precision of the suggested FEM model is identical to that of the traditional FEM models regarding the case of elastic joint behaviour.

Study of impact of bed joint reinforcement on load-carrying capacity and crack resistance of masonry walls made of calcium silicate units

This paper presents results from testing eight full-scale walls made of calcium silicate units. Tested walls were reinforced in the bed joint or unreinforced, with or without openings. The used reinforcement was steel truss type and fibreglass mesh coated with plastic. Tests also looked at the impact of reinforcement on load-carrying capacity and crack resistance in areas of stress concentration near openings, and at connection between perpendicular walls. Reinforcement was found to have a lower impact on load-carrying capacity, and a bigger impact on crack resistance of the masonry. The reinforcement effect on load-carrying capacity of walls reached ±10%. The flexible fibreglass mesh reinforcement caused an increase in load-carrying capacity of the lintel support zone, but did not have an impact on the load capacity of the zone of wall connections. The rigid steel reinforcement caused an increase in load-carrying capacity of the zone of wall connections, and a drop in the lintel support zone. Reinforcement in the spandrel area could increase the level of stress, at which a first crack occurred in the masonry, even by 70%. Cracking stresses at the connection between walls were even higher, up to 70–120%, due to the use of reinforcement.

Strength and stiffness characteristics of A3003 aluminum honeycomb core sandwich panels

The demand for lightweight structures made of sandwich panels is ever increasing in many Industrial sectors. World over numerous researches are actively pursued on several aspects of sandwich in this area in terms of weight and cost reduction. Sandwich panel is a composite structure and it is an excellent alternative material in place of weight reduction without sacrificing its strength and stiffness characteristics. Sandwich panels consist typically of two thin face sheets and a lightweight thicker core. The core provides low density, relatively high out of plane compression, stiffness and shear properties. These panels find wide application in public transport industry, aeronautical sectors, building industries, tooling machines and serigraphy. Today every engineered product undergoes an analysis before realizing production and with ubiquitous application of AHCS panel, it’s imperative that static properties of AHCS panel are precisely known in order to predict behavior of the structure. The heterogeneous nature of honeycomb core and complex load transfer paths make it behave like orthotropic material and prediction of stiffness becomes tedious and difficult. The geometrical characteristics of honeycomb core sandwich panels as well as their mechanical properties such as compressive strength, flexural stiffness, core shear moduli, shear strength and stiffness are analyzed. In this paper, the stiffness of Al hexagonal core sandwich panel of different span length is determined by Finite Element and the same is compared with theoretically obtained results. The sandwich panels are available in various shapes and sizes to the service requirement. The commercially available sandwich panels have different core materials such as foams, FRPs and metallic and nonmetallic materials. The structure of the core typically varies as truss type and honeycomb. The face sheets and the core materials are bonded using thermo-set resins.

The Performance between Two Long-span Roof Trusses of Cold Formed Steel with Back to Back Channel Section

Cold formed steel (CFS) is mostly used for short span structures in Indonesia because its advantages in cost and time efficiency. However, there is still limited number of long-span construction using cold formed steel because its buckling issue. Throughout the time, there are many researches that revealed the buckling issues can be prevented; one of them is combining their section. Then, CFS structure should give full structural performance. This research aims to analyze the performance of long-span roof truss, 24 m, using CFS back to back channel section. Two types of roof trusses, model 1 and model 2, are compared to get better configuration for long-span roof truss. Analysis is conducted by 2D model and analytically calculated based on SNI 7971:2013. The results are the maximum axial tensile force and axial compressive force, and also deflection. They will be compared to CFS back to back channel section capacity. This analysis obtained the stress ratio and deflection of both configurations. Based on analysis results, CFS back to back channel section safely withstands resisting axial forces by giving compressive ratio number around 0,54-0,72. Then, model 2 has given better structural performance, stress ratio and deflection, than model 1.

Michell truss type theories as a Γ-limit of optimal design in linear elasticity

Abstract We show how to derive (variants of) Michell truss theory in two and three dimensions rigorously as the vanishing weight limit of optimal design problems in linear elasticity in the sense of Γ-convergence. We improve our results from [H. Olbermann, Michell trusses in two dimensions as a Γ-limit of optimal design problems in linear elasticity, Calc. Var. Partial Differential Equations 56 2017, 6, Article ID 166] in that our treatment here includes the three-dimensional case and that we allow for more general boundary conditions and applied forces.

NUMERICAL ANALISIS OF THE STRAINS AND STRESS STATES REINFORCED CLAY BRICK MASONRY WALLS HORIZONTALLY SHEARED

This paper presents the results: stress and strain of bed joints mortar, masonry units, reinforcement bars and mechanism of cracking of numerical simulations using ANSYS of reinforced brick wall in the horizontal shear. Willam-Warnke (WW-5) failure criterion for mortar and bricks and Huber-Mises-Hencky (HMH) plasticity surface for bed joints steel reinforcement (steel smooth bars and truss type reinforcement) has been used. Coulomb-Mohr (CM) criterion in the contact surfaces of mortar and bricks have been used in the interface elements. Numerical calculations showed satisfactory convergence of research in the patterns of cracking; and the load-strain relationship was similar to the results of research with regard only to the cracking time. Destructive force numerical models Hu,cal correspond to the forces observed at the first cracks in the walls Hu,mv. Reduction of transverse and longitudinal deformation of mortar bed joints have been reported in the immediate vicinity of the bars, and the reduction of the main stress of the bricks is reported in the case of the use reinforcement.

Two-Stage Method Applied for Approximate Calculations of Selected Types of Statically Indeterminate Trusses

The paper presents examples of approximate calculations of force values in members of selected types of trusses, which are at the same time an internal and external statically indeterminate systems. The two-stage method makes possible the approximate calculation of such trusses by help of, for example, the Cremona’s method. In each stage, a statically determinate truss is considered, pattern of which is defined by removing from the basic truss a suitable number of members. There are also presented results of calculations of the same trusses done by means of suitable computer software together with analyses and comparison of outcomes.

ОБОСНОВАНИЕ КОНСТРУКТИВНЫХ СХЕМ ПОДВИЖНОГО СОСТАВА ДЛЯ ОРГАНИЗАЦИИ ПЕРЕВОЗКИ АВТОПОЕЗДОВ И КОЛЕСНОЙ ТЕХНИКИ

The work is dedicated to the substantiation of design schemes of platform-cars for the organization of road-trains and wheel engineering transportation by railway. In the paper the analysis presented of rolling-stock designs for the organization of road-train and wheel equipment transportation, legislation requirements, a standard legislation for designing rolling-stock, requirements of transport operators and a logistic infrastructure existing in the country allowed formulating criteria for the choice of an efficient design scheme of a platform-car. 
 In accordance with the criteria accepted there are offered three versions for the design of cars. In the first two versions of platform-cars there is foreseen a lower stationary platform on a based length. The difference of the second version consists in the application of a bearing element in a truss structure as a basic one. For both designs there are obtained utility patents. The third version provides for the presence of a load lifting platform. For the substantiation of an efficient design of a platform-car there is carried out an analysis of operation engineering-economic properties, values of driving dynamics, strength, fatigue life and a life cost of three car versions under consideration. The comparison of designs according to all parameters mentioned allowed defining the fact that taking into account the specificity of the domestic legislation, requirements of standard-regulation documentation for rolling-stock designing, and also the interests of transport operators the most efficient design scheme is a platform-car with a stationary lower level of a load platform on a base length and a bearing design of a truss type.

Experimental and comparative study on hollow brick walls having truss and ladder type reinforcement under axial loading

Now-a-days, hollow bricks are usedat variousconstruction buildings and compound wall. Hollow bricks are strong and cheap in cost and available everywhere. Generally,hollow bricks are used because it reduces heat and make the building in cool.The objective is to investigate the engineering properties of hollow brick masonry walls incorporated with reinforcement. This project involves material collection, quantitative results, construction of hollow brick walls and testing of walls. The ultimate target is to identify the reasons of crack failure, to identify the strength and stiffness reduction, when truss and ladder type reinforcement is placed in the wall.

Analyse von vertikal belasteten Porenbeton‐Wänden

AbstractThe paper describes the results of testing six autoclaved aerated concrete (AAC) walls on a natural scale. The walls were made of 18 cm wide blocks and thin layer joints. Reinforced and non‐reinforced walls were tested. Basalt grids and typical steel reinforcement (truss type) were used as reinforcements. The load was applied by a reinforced concrete rim beam. In the first part of the tests, the impact of the opening (window) on stress distribution and the load capacity of the wall was analysed. In the second part of the tests, the unequally loaded connection zone of perpendicular walls was analysed. The results were used to draw practical conclusions on rules of additional reinforcement of zones surrounding openings and connection zones of perpendicular walls.

FIRST RESULTS FROM A STUDY ON THE EFFICACY OF USING VIRTUAL REALITY (VR) TO TEACH TRUSS MECHANICS

In 2018, the University of Saskatchewan’s College of Engineering established a Virtual Reality Teaching and Cloud-based Learning (or ViRTCL) lab featuring three high-performance HTC Vive Pro VR stations that will be used for day-to-day teaching and for pedagogical research. Also during 2018, we worked with local start-up Sprockety Ventures Inc to develop custom VR software (called TrussVR©) that is designed to help students learn about trusses. In the Fall term of 2018, a pilot study began to evaluate the learning efficacy of TrussVR©. This paper conveys the initial quantitative results of the pilot study.
 For this study, TrussVR© existed as a 3-module lab experience. The first module exposed students to various types of trusses, and allowed students to rapidly test the trusses with applied forces of their choice. The trusses “responded” by showing the qualities of their internal forces including intensities of compression and tension, as well as zero-force members (ZFMs). The second module consisted of two parts. The first showed the distribution of forces in the two-force members (2FMs) of a truss and asked students to apply an external load that would create those internal forces. The second did the reverse i.e. it displayed a truss and an external force and asked students to label the 2FMs with C (compression), T (tension), or Z (ZFM). The third module was a design module where students constructed a bridge truss and tested it.
 In September 2018, students were recruited from the first-year GE 124 Engineering Mechanics I (Statics) class to take part in a pilot study on TrussVR©. Ethics clearance had been granted by the Behavioural REB of the University of Saskatchewan. More than 160 students volunteered. They all completed a “pre-survey” before the lecture content on trusses began. The pre-survey explored issues of knowledge, skills, and attitudes as they pertained to trusses and VR. The study participants were then randomly divided into three groups: no truss lab, conventional truss lab (Pasco© construction set), and TrussVR© lab. During the time of the course when study non-participants completed the Pasco© lab, the study participants completed either no lab, the Pasco© lab, or the TrussVR© lab. After the lab sessions for trusses were completed, all study participants completed a “post-survey” that re-examined knowledge, skills, and attitudes towards trusses. Furthermore, exam marks of the study participants for truss and frame questions were examined for statistically significant differences. Finally, in mid-February, study participants redid the post-survey to examine any differences between conditions in shorter- and longer-term changes in knowledge, skills, and attitudes. 
 Initial results focus on any statistically significant differences between pre, post, and distant-post results on the surveys, as well as on exams, between and within experimental groups. Given how the exams were marked, we were also able to look for patterns and differences in different sections of answers in addition to overall scores. We anticipated that there may be differences in attitudes towards trusses between the three experimental groups (no lab, Pasco© lab, TrussVR© lab). There may also be differences in skills and knowledge.

Simulation of the frequency response of the ERC 1400 Bucket Wheel Excavator boom, during the excavation process

Abstract The paper deals with the modal analysis and frequency response analysis of a bucket wheel excavator (BWE) boom, obtained by simulation, based on a virtual model of an existing BWE boom. The boom, which generally is realized as a spatial truss, is the most vulnerable subsystem of the BWE, being submitted to severe operational loads characterized by very pronounced cyclical, dynamic and stochastic variability. This vulnerability is the consequence of its shape and constructive parameters and the nature, source and character of the external exciting loads to which it is exposed. The classical approach recommended by standards and norms cannot predict the occurrence of failures caused by vibration, which produces fatigue due to the load’s cyclical variability and the deformation produced by resonant vibration of some constitutive elements. As exciting load we considered the operational forces acting on the bucket wheel. In this manner we can take into account the constructive features – with modal analysis, and the vibration regime – with frequency response analysis. The proposed method is useful both in the design phase of new load-bearing structures of truss type subjected to high-variability forces, and also in refurbishment or improvement phases of the existing structures of this kind.

Truss spacing on innovative composite walls under compression

Double skin steel-concrete composite walls offer structural merits over conventional reinforced concrete walls in terms of high strength, good ductility and convenience for construction. The stability of the external steel faceplates is significantly influenced by the types of internal mechanical connectors and the ratio of connector spacing to plate thickness. In this paper, a new type of steel truss was proposed as the fastener to connect the two faceplates. Compressive tests were conducted on three full-scaled composite walls with different truss spacing. The structural response of the walls was comprehensively discussed in terms of failure modes, load-axial displacement response, buckling stress, stiffness, ductility, strength index, load versus out-of-plane displacement response, and load-strain curves. The influences of truss spacing on key parameters were explored in details. The test results showed that the truss spacing could considerably affect the buckling shapes, load-carrying capacity, stiffness and ductility of the specimens.