Load-bearing Strength Research Articles

Case study for ditch cover with ultra-high-performance concrete

The case study is to explore the ditch cover with ultra-high-performance concrete (UHPC) and mainly focuses on seven different contents of steel fibers (0, 0.5 %, 1 %, 1.5 %, 2 %, 2.5 %, 3 %) as variables. The fabrication of the UHPC ditch cover was performed with 60㎝× 35㎝ ditch cover mold for UHPC casting and added wire mesh for 2 layers. The test parameters of the ditch cover included the spot welded wire mesh with iron or steel, the steel fiber content, the number of openings, and the thickness. The number of openings in the ditch cover model is 8 holes and 12 holes. The case study is to find a UHPC ditch cover that is strong enough to withstand the weight of a heavy vehicle. The purpose of the research is to develop a UHPC ditch cover, and compare the weight, load bearing, and unit price with zinc grid ditch cover, cast iron ditch cover, and FRP ditch cover. The results show that the compressive and flexural strengths of UHPC with 0–3 % steel fiber content can be rapidly increased by 40 % and 260 %, respectively. The study found that the UHPC trench cover is added with 3 % steel fiber, double-layer spot welded steel mesh, with a thickness of 4 cm and 8 openings, its load-bearing strength can exceed 11 tons, and the load capability/price (C/P) value is extremely high.

Weight optimization and finite element analysis of automobile leaf spring: A design construction referred to electric vehicle

In the current era, an automobile vehicle company’s major focus is now on conserving natural resources, reducing consumption of fuel, and reducing the weight of vehicle components. To reduce greenhouse gas emissions and fuel consumption and mitigate global warming, an electric vehicle will be a viable option. However, the EV’s main issue is the vehicle’s battery longevity. More power is necessary to drive a vehicle. The best solution to the issue is to reduce the vehicle component weight. Electric Vehicle suspension systems are another sector in which these developments are performed on a regular basis. Substantial steps are being taken to improve the vehicle ride quality. In this study, static and dynamic analysis has been carried out by finite element analysis at Ansys workbench and taken structural steel material for mono leaf spring. In composite material, carbon fiber and glass fiber have been considered as reinforcement and resin epoxy has been taken as matrix for mono leaf spring. The composite material fabrication has been accomplished layer by layer at Ansys ACP. After analysis, this study has revealed that by using composite material a magnificent amount of weight reduction has been achieved without sacrificing load-bearing capability, strength, and rigidity.

Performance of steel-reinforced square CFST stub columns loaded in axial compression: Experiments

A steel-reinforced concrete-filled steel tubular column is a type of concrete-filled steel tubular (CFST) column reinforced by embedded steel profile. The inner carbon steel tube reinforced square concrete-filled stainless steel tubular column (SR-CFSST) has not been systematically investigated. In this project, stub composite columns with various experimental parameters were tested as loaded in axial monotonic compression, considering the effects of the concrete strength, column size and wall thickness of the steel tubes. The mechanical behaviour of stub columns was analysed in terms of ultimate load-bearing capacity, strength index, ductility, and failure modes. The calculation methods in five codes, including GB 50936, DBJ/T 13–51, Eurocode 4, ANSI/AISC 360 and AIJ, which are widely used for ordinary CFST stub columns, were compared. Finally, a simplified calculation method for the SR-CFSST stub columns was proposed for predicting the ultimate bearing capacity. The predicted results agree well with test results and the simplified calculation method can be used to design SR-CFSST stub columns loaded monotonically in axial compression.

Techniques for Processing Experimental Data for Structural Health Monitoring of Bridges

Reliability of transport artificial structures and transit of trains at sanctioned speed should be provided with the necessary and sufficient load-bearing capacity, strength, rigidity, and stability of engineering structures.The objective of this work was to substantiate the possibility of using well-known methods for controlling the stress-strain state of structures using automated systems of structural health monitoring of bridge spans.It is extremely important regarding operation of transport artificial structures designed according to the standards of the first half of the 20th century.Under these conditions, the experimental determination of the stress-strain state of bearing structures of bridges becomes the most important component of the task of a comprehensive assessment of physical wear and tear as well as of operational reliability of the structures. Monitoring the structural health and technical condition of bridges and planning of timely measures aimed at the repair, strengthening or reconstruction of spans will extend their service life and ensure safety during operation.Maximum permissible deflections of spans under a movable temporary vertical load have been revealed since to ensure smooth movement of vehicles it is necessary to control horizontal longitudinal and transverse displacements of the top of the bridge piers, as well as vertical settlements.The paper suggests methods of interpreting data measured by inclinometers and electric strain gauges, tensiometers to use them in an automated system for monitoring the structural health of railway bridges. The method of strain measurement is described in detail in the proposed options for installing resistance strain gauges on structures to measure tensile-compression stresses and longitudinal forces due to a temporary vertical load.Monitoring the technical condition of bridge structures, using the methods for measuring deflections and deformations proposed by the authors in this article, will make it possible to assess the change in bearing capacity of the structure over the entire period of operation. The study used regulations and experience of the Russian Federation and the Republic of Kazakhstan.

Estimation of creep and damage accumulation in thin-walled concrete structures

Long-term strength investigations of construction elements made of reinforced concrete (RC) under creep conditions are considered. A calculation method that allows determination of the load-bearing capacity and long-term strength of RC thin-walled elements under short- and long-term loading is proposed. The method is based on a combination of the finite-element method for solving boundary value problems at each time step and the finite-difference method for integrating the initial value problems. The numerical results are compared with experimental data obtained in the loading–unloading mode during long-term deformation. An example of creep and damage calculations in the RC coating and recommendations for parameter selections are given.

An examination of two different approaches for the study of femoral neck fracture: Towards a more relevant rodent model.

Femoral neck fractures are a massive personal and health programme burden. Methods to study femoral neck strength, across its combined trabecular and cortical components are therefore essential. Rodent ovariectomy-induced osteoporosis models are commonly coupled with ex vivo 3-/4-point bending methods to measure changes in femoral cortical diaphysis. The loading direction used to assess these properties are often non-physiologic and, moreover, these ovariectomy models are linked to marked weight gain that can influence the biomechanical properties. Herein, we explore whether more physiological axial ex vivo loading protocols applied to femoral neck samples of ovariectomised (OVX) rodents provide anatomically-relevant models for the assessment of strength. We examine the use of mouse and rat femurs, loaded in constrained and unconstrained configuration, respectively, and explore whether weight-correction increases their utility. Accordingly, the mid-shaft of the proximal half of femurs from OVX and sham-operated (Sham) mice was methacrylate-anchored and the head loaded parallel to the diaphysis (constrained). Alternatively, femurs from OVX and Sham rats were isolated intact and axially-loaded through hip and knee joint articular surfaces (unconstrained). Yield displacement, stiffness, maximum load and resilience were measured and fracture pattern classified; effects of body weight-correction via a linear regression method or simple division were assessed. Our data reveal significant deficiencies in biomechanical properties in OVX mouse femurs loaded in constrained configuration, only after weight-correction by linear regression. In addition, evaluation of rat femur biomechanics in unconstrained loading demonstrated greater variation and that weight-correction by simple division improved scope to reveal significant OVX impact. We conclude that greater femoral neck fracture susceptibility can indeed be measured in OVX rodents as long as multiple biomechanical parameters are reported, care is taken in choosing the method for assessing load-bearing strength and weight-correction applied. These studies advance the establishment of more relevant rodent models for the study of femoral neck fracture.

Multiaxis three-dimensional (3D) glass fiber preform/cementitious matrix concrete composites: Experimental characterizations by panel test

Multiaxis three-dimensional (3D) alkali-resistant continuous glass fiber/cementitious matrix concrete composites were developed using the “winding and molding” method. The panel properties of the concretes were experimentally investigated and compared with the neat concrete. The experiment revealed that the load-bearing capability, strength and energy absorption properties of the multiaxis three-dimensional concretes were significantly influenced by the placement and orientation of the reinforcement fiber. The newly developed concrete composite was found to have the strain hardening behavior which attributed to an improved energy absorption performance of the concrete. It was also identified that four directional glass structure (ARG-4D) demonstrated somewhat better energy absorption performance compared to that of the biaxial (ARG-2D) and uniaxial (ARG-1D) structures because of the fiber orientation in the multiaxial direction in the concrete. Further investigation of the fractured four directional glass fiber/cementitious matrix concrete (ARG-4D) showed that the fiber-matrix interfacial debonding in each yarn set, local matrix breakages, yarn bridging due to tensile strengthening, tensile pull-out of outer filament and stick-slip frictions between the filament TOWs and the cementitious matrix were the principal fracture mechanisms. The micro-cracks occurred in multiaxis concretes were restricted by the multiaxis 3D fiber architecture. The multiaxis three-dimensional alkali-resistant continuous glass fiber/cementitious concrete can be considered as the damage tolerant structures with regard to neat concrete.

ИЗМЕНЕНИЕ НЕСУЩЕЙ СПОСОБНОСТИ КОРРОЗИОННО- ПОВРЕЖДЕННЫХ ПЛИТ ПЕРЕКРЫТИЯ В ЗАВИСИМОСТИ ОТ ГЛУБИНЫ ПОВРЕЖДЕНИЯ БЕТОНА РАСТЯНУТОЙ ЗОНЫ

In this work, the influence of the depth of tensile concrete deterioration on the load-bearing strength and deflections of precast reinforced concrete slabs were determined experimentally. The momenta determination and measurement of deflections was carried out by loading the structure stepwise. Analysis of the results of the study indicated the following: as the plates are damaged, with the increase in the height of tensile concrete deterioration, the stress diagram gets gradually filled in the compressive sectional area and its height decreases, which can lead to the destruction of the structure. At the same time, the shear and bending moment diagram of sectional deformation gets curved. As the slab deflections increase, its load-bearing strength decreases.

Comparative Analysis on Use of Polymer Fibres from Recycled Polyethylene Terephthalate into Reinforced Concrete Solutions

Fibre-reinforced concrete cannot replace the ordinary reinforced concrete. However, there are areas of use in which fibre-reinforced concrete can be used alternatively or in addition to the ordinary reinforced concrete, offering several advantages, some of that being presented in this study. The basic idea is that reinforcements create a multi-directional �mesh� within the cementitious matrix that will make concrete stronger. In fact, adding the fibrous material to concrete will increase the strength. In this sense, the micro-fibres primarily work to prevent micro- or shrinkage cracking, which mostly occurs during the initial curing process of the concrete, or those critical first 28 days. By contrast, the macro-fibres provide load-bearing strength after the concrete cracks. But, in fact, the subject is more complex. The types and size of fibres, their distribution and orientation are a hugely complex topic. Fibres, of whatever nature, have been found to improve the properties of concrete. Fibre-reinforced concrete provides an alternative to conventional reinforcement, with the advantage of time and reduced costs of performing maintenance work. The complexity of various fibre use presents challenges for the construction sectors that may be beyond current levels of expertise. In this study, particularities of concrete reinforced with polymer fibres are presented. Also, a comparative study is presented, based on our previous works in area of the concrete reinforcing with recycled polyethylene terephthalate (PET).

Soil strength and load bearing capacity measurement techniques

In this research, the interest will be given to studying the load bearing capacity and strength of soil terrain, resulting from machine-soil interaction. A small introduction will define terramechanics studies and its importance when dealing with machine-terrain interaction. The axial load acting on a terrain will lead to the sinkage of the machine, thus considering this load will help in studying the load bearing capacity of the soil and ending up with results that are beneficial to terramechnaics studies, so improvement in the machine design or choosing the suitable machine for specific terrain. This review shows the studies and models that researchers obtained and dealt with regarding the load bearing capacity. The techniques and the measurements used in finding the load bearing capacity of soil will be explained (Bevameter, Cone penetrometer).

Early Hypoglobus in Orbital Floor Reconstruction With Resorbable Implants.

Among the variety of materials developed for facial bone surgery, resorbable implants are widely used in orbital wall reconstruction. There are many advantages in selecting resorbable implants, such as minimal foreign body reaction and adjustability within the damaged orbital floor. Resorbable implants are supposed to remain in place over 1 to 2 years to hold the structure of immature healing tissue surrounding the bony defects. However, some patients who have undergone orbital wall reconstruction surgery with resorbable implants suffer from early hypoglobus. This retrospective study was performed from January 2014 to August 2019 and follows 39 patients with unilateral pure orbital floor fractures. All orbital floor reconstruction was performed using resorbable implants via the transconjunctival approach. Exophthalmometer measurements and CT scans showing the degree of implant sagging were used to provide an index of hypoglobus. Most patients showed hypoglobus over 3 to 4 months follow-up. The size of bony defect in the orbital floor showed positive correlation with follow-up exophthalmometer measurement and degree of implant sagging. Orbital floor reconstructed with resorbable implant tends to lose load-bearing strength gradually, especially in large bony defects. Therefore, surgeons should be cautious about using resorbable implants for the maintenance of reconstructed orbital floor, especially in large bony defects.

Study on Improvement of Black Cotton Soil by Using Fines of Concrete Cube & Brick Demolition Waste

Subgrade soil is a primary part of a road crust which gives considerable strength and support to the whole pavement structure from below. If the subgrade soil exhibits a weak soil then improvement of load-bearing strength properties of that subgrade soil is done by soil-stabilization technique. This project aims to conduct a study to check the improvements in properties of Black Cotton (BC) soil by adding Fines of Crushed concrete cube and Brick waste separately. By varying percentage of Fines of Concrete Cube Waste (FCCW) at 0%, 20%, 40% and 60%, the soil parameters such as Compaction characteristics, CBR and Shear Strength were studied. These values are compared to that of a untreated BC soil. Similarly, the varying percentage of Fines of Brick Demolition Waste (FBDW) at 0%, 20%, 40% and 60%, the soil parameters only considered was Compaction characteristics. The first approach of BC stabilized using FCCW, the Maximum Dry Density increased from 1.504g/cm3 to maximum 1.708 g/cm3, decrease in Optimum Moisture Content and later increase, CBR value increased from 2.05%to maximum 7% and Shear strength increased from 377kN/m2 to maximum 1390 kN/m2 at 20% FCCW respectively. The second approach of BC stabilized using FBW, the Maximum Dry Density increased from 1.565g/cm3 to maximum 1.702 g/cm3 and decrease in Optimum Moisture Content at 20% FBDW respectively. However, in the light of studies conducted, the 20% of FCCW and 20% of FBDW are considered as the optimum proportion of the FCCW and FBDW resulting in maximum strength and performance as observed from UCS test results in the first approach.

Lightweight design of truck frame

Trucks are an important branch of the automotive field, and their market demand has been and will maintain a stable level for a long time. In this paper, a truck with a load capacity of 6t is selected as the research object. The frame of the truck is a side beam frame, which is riveted by two longitudinal beams and eight cross beams. The solid model of the truck frame is established by three-dimensional modeling software, and then the finite element software is used for static analysis of the frame, and the maximum deformation, the position of the maximum deformation, and the maximum Stress, maximum stress point. The analysis results show that the structural strength of the frame is far greater than the load-bearing strength, which meets the requirements of use, and there is a large space for lightening the structural materials. The structural optimization design of the frame is carried out, and the weight of the optimized frame is reduced by 8.4% under the premise of ensuring the strength requirements. The maximum stress under the full-load bending condition is reduced from 207.3MPa to 177.86MPa, achieving the lightweight goal.

Analytical models for predicting the load-bearing strength of beam-to-column joints in a composite steel frame

Two analytical models are developed to predict the load-bearing capacity of a beam-to-column joint inside a slim-floor composite frame. The load inside the joint is transferred mainly by a steel console welded to a concrete-filled steel column. Because of the asymmetric nature of plastic collapse mechanism of the steel console, a two-parameter model is developed in two mechanisms: a mechanism excluding the axial force at hinge lines, and an intuitive mechanism including the influence of arising axial force. The models are verified by numerical results and used further for parametric studies. The results indicate that both models predict the limit load of the joint well. The studies also show that the model excluding the normal force is simple to use but can be a bit conservative, whereas the model including the normal force better predicts the load-bearing capacity of the joint, particularly if larger indentation is allowed. Based on the parametric studies, a general equation is then proposed. Compared to the method provided in design code as EN 1993-1-8, the proposed equation predicts the higher load-bearing capacity; thus leading to a more economical design in practice.

ENGINEERING PROCEDURE FOR EVALUATING THE LOAD-BEARING CAPACITY AND LIFE OF A DEFECTIVE STRUCTURE

A piece of rocket and space hardware may consist of tens of thousands of parts. Virtually every as-built piece of hardware has some non-conformances to the design documentation. Manufacturing defects often occur or are discovered during the final stages of the vehicle assembly or pre-launch processing. In such cases, removal of the non-conformance is either impossible or is too difficult and costly. The procedure described in the paper makes it possible to evaluate the degree of impact of a typical defect on the load-bearing capacity, strength, leak integrity, and life of a structure under its operating conditions. Sections of the procedure include description of operations involving non-destructive testing, determining loads on the vehicle and other operating conditions, stress-strain analysis, experimental determination of the material properties, prediction of the crack kinetics from the standpoint of fracture mechanics. The procedure gives a structural analyst an algorithm for solving the complex problem of estimating the service life, which consists of a sequence of specific tasks: developing the finite element model, classifying the defect, constructing the loading block, analyzing stress-strain behavior, predicting the behavior of the initial defect. Introducing the procedure into engineering practice will make it possible to increase validity of the estimate of the load bearing capacity and life, and, therefore, of the reliability and safety of the vehicle operation. Key words: structure, defect, crack, loads, stress condition, material properties, fracture mechanics, strength, leak integrity, life.

Analysis on failure mechanism of CFRP double-tap interference-fit joint

Composite interference-fit joints have attracted much attention because they can effectively reduce the stress concentration around the holes during loading. In this paper, the load-bearing mechanism and strength of a typical double-lap structure under static load are studied through experiment and finite element method. In order to eliminate the influence of bending moment and other factors, a special fixture was designed to study the damage failure mechanism of CFRP interference fit joint under pure tension. The finite element model of CFRP interference fit double lap structure considering both intralaminar and interlaminar damages was established with ABAQUS user subroutine and cohesive element. The damage propagation mechanism during loading process is revealed and the ultimate bearing strength is predicted by comparing the results of experiment and finite element model.

Design and optimization of noise barrier based on mechanical analysis of ANSYS

In order to ensure the structural strength of the noise barrier and optimize its design, in this paper, the Finite Element Analysis software ANSYS is used to model the noise barrier, and the mechanical properties are analyzed. The effects of different numbers of reinforcing ribs on the deformation and stress of the noise barrier under natural wind are studied. From the perspective of wind load, load bearing and bolt strength, the number of reinforcing ribs of the noise barrier is optimized. The results show that the structural strength of our self-developed noise barrier can meet the requirements. This design method provides guarantee for the future engineering design and application.

FORMATION OF RESIDUAL STRENGTH OF STRUCTURAL FIBER IN CONDITIONS AFTER FIRE

The article presents the results of dynamic mechanical tests of fiberglass specimens under the conditions of the effects of intense heating on them, which corresponded to the development of a slowly developing fire. It is established that with intensive heating at the initial stage of fire, the considered type of fiberglass loses its initial strength, but then, upon cooling, acquires increased rigidity, while maintaining sufficient integrity and relative structural functionality. In our view, this increase is due to the significant increase in the carbon fraction in the polymer binder with the formation of a more densely packed structure due to the formation of sites with associated aromatic fragments. At the same time, the drop in strength occurs due to the formation of a sufficient number of voids (pores and cracks), the occurrence of which is characteristic of materials of organic nature (plastics based on synthetic polymers) in the process of thermal oxidation destruction under intense heating. It is established that the degree of conservation of the load-bearing strength of the fiberglass can be arranged in the following order: bending> stretching> compression. This behavior of the material indicates the use of additional structural measures when using it as the supporting elements of construction and technological structures. The determining factor in the observed modification of the composite is the extent of the passage of the pyrolytic transformations of the polymer bond, which can indirectly be characterized by a change in the dynamic mechanical properties of the material under intense heating. The main role is played by the binder component - the epoxidized naphthalene type oligomer, whose function is reduced to the ability to play a role in the volume of the polymer matrix of coke formation germs. The above composition of components and the method of its production allows to develop polymeric composite materials without the use of additional components - flame retardants (retardants), which complicate the technology of obtaining the composite and in some cases reduce its initial physical and mechanical properties. Keywords: fiberglass, residual strength, fire aftereffect, dynamic mechanical tests, epoxidised dinaftol

Experimental Examinationof Hollow Brick Masonry Wallwith Reinforcement

The research aims at conducting a quality research with Reinforcement of a hollow brick wall. The empty internal sections significantly lower the dead load. With a better surface finish, the side of the block was cast, minimizing the cost of plastering. Several sample mixes are tested to achieve a finished surface. The respective frames were cast with and without reinforcement and the test results were compared. The blocks were used to build masonry walls and ' load-bearing strength ' of the walls was tested. It is possible to use the reinforced hollow block as a load-bearing wall. Nearly 75 percent of the deaths related to the earthquake in the last century,Buildings have collapsed, the majority of which (more than 70 percent)is due to the collapse of buildings made of masonry. Most of the properties in India are Unreinforced Masonry (URM) buildings that are weak and vulnerable even under moderate earthquakes and that function on the wall due to high wind forces, causing severe damage to high wind loads and it is recognized that Reinforced Masonry Building has many advantages over unreinforced masonry building.The use was very limited in Indian building practices and there are still no approved codes and shear walls were used in most constructions, even in mild earthquakes, instead of reinforced masonry walls.

Strength design of concrete-infilled double steel corrugated-plate walls under uniform compressions

Concrete-infilled double steel corrugated-plate walls (CDSCWs) are composed of two steel corrugated-plates (SCPs) which are connected through bolts, and concrete filled the spacing formed between the two SCPs. Two vertical boundary elements are installed additionally at both sides of CDSCWs. On the one hand, the corrugated configuration of SCPs has great improvement on the load-bearing efficiency of CDSCWs; on the other hand, much higher bearing capacities and better seismic performance for CDSCWs are provided owing to the interactions among SCPs, bolts and infilled-concrete. This paper investigates the load-bearing mechanism and strength design formulae of CDSCWs under compressions. Since SCPs are prone to local buckling failure between two rows of bolts under the conditions of large vertical bolt spacing and small thickness of SCPs, this paper mainly focuses on the load-bearing mechanism of SCPs in CDSCWs under uniform compressions. The unilateral constraint on SCPs provided from infilled-concrete and the restraining effect on the flexural deformation of SCPs owing to bolts are considered. At first, series of finite element (FE) eigenvalue buckling analyses are conducted to study the elastic buckling behavior of SCPs subjected to uniform compressions. On the basis of Euler's formula, the formulae for predicting the elastic buckling stresses and corresponding normalized slenderness ratios λs of SCPs are achieved respectively. The instability performance of SCPs under uniform compressions is then investigated through FE nonlinear analyses, and accordingly the stability coefficient φs is attained. The corresponding φs−λs curve is therefore established in order to calculate the ultimate bearing capacities of SCPs. In addition, the cooperative performance of material strengths between SCPs and concrete is analyzed numerically when CDSCWs reach their compressive ultimate strength. With this consideration, the design method for predicting the cross-sectional strength of CDSCWs under compressions is proposed. Moreover, a CDSCW specimen with I-section is tested under a compressive load. Its cross-sectional strength is investigated experimentally. The results of the experiment coincide with those of numerical simulation, this verifying the safety and validity of the design method for cross-sectional strength design of CDSCWs.