Longitudinal Beams Research Articles

Effect of One- and Two-Stage Shear Cutting on the Fatigue Strength of Truck Frame Parts

The longitudinal and transverse beams of trucks are manufactured with a large number of holes to fasten brackets for springs, fuel tanks, batteries etc. The quality of the holes, which is particularly influenced by the manufacturing process, has a major influence on the fatigue strength of the beams and thus the service lifetime of the vehicle. In most cases, the holes are produced using the highly economical shear cutting process. Previous investigations have shown that the fatigue strength of thin sheets can be increased by adjusting the shearing parameters and using a two-stage shear cutting process. This paper discusses the difference between one- and two-stage shear cutting on the hole quality of components made of S500MC (1.0984, thickness 8 mm) and its resulting fatigue strength. The hole quality is characterized by the geometry of the shear cut surface, its roughness, microstructure, and microhardness. It was shown that the two-stage shear cutting process allows producing holes of better quality than the ones manufactured by a one-stage shear cutting process. Furthermore, this resulted in an improved fatigue behavior.

Hybrid modelling of low velocity zones in an asymmetrical channel with sidewall longitudinal rib to assist fish passage

AbstractChannels with longitudinal beams have been studied for decades in chemical engineering, environmental and sanitary engineering, aeronautics, astronautics, biology and geology. In the current study, a combination of physical and numerical Computational Fluid Dynamics (CFD) modelling was undertaken to test whether an asymmetrical channel equipped with a sidewall longitudinal rib could provide flow conditions conducive to upstream fish passage. The study focused on small‐bodied fish and juveniles of larger fish, typically less than 100 mm in total length. A detailed hydrodynamic study was conducted in an asymmetrical rectangular channel equipped with a sidewall square rib in a culvert barrel channel. Both free‐surface velocity and boundary shear stress measurements showed strong secondary currents of Prandtl's second kind. The channel asymmetry contributed to intense secondary motion, associated with turbulent dissipation. The channel design provided a small well‐defined highly turbulent low‐velocity zone beneath the rib. In the context of hydraulic structure designs, uttermost care must be considered because of manufacturing, installation and operational practices. In many instances, alternative engineering designs with small baffles and asymmetrical appurtenance should be preferred to assist with fish passage in hydraulic structures.

The Influence of the Welding Process on the Ultrasonic Inspection of 9%Ni Steel Pipe Circumferential Welded Joints.

This work aims to compare the ultrasonic inspection of 9%Ni steel joints welded with the Gas Metal Arc Welding (GMAW) process and Shielded Metal Arc Welding (SMAW) process. These are the two most widely used processes used to weld pipes for CO2 injection units for floating production storage and offloading (FPSO) in the Brazilian oil and gas industry. The SMAW equipment is simple and portable, which is convenient for the FPSO; however, the GMAW process has the advantage of welding with high productivity. In this study we performed a numerical simulation using the software CIVA, 11th version, to analyze the behavior of ultrasonic longitudinal wave beams through GMAW and SMAW dissimilar weld joints. Ultrasonic tests were performed on calibration blocks drawn from both welded joints to evaluate the simulation results. The results are discussed with regard to the microstructure of the weld metal via electron backscatter diffraction (EBSD) analyses. The SMAW process presented better inspection performance than the GMAW process in terms of attenuation and dispersion effects. Although the SMAW had a better outcome, for both processes the configuration of 16 active elements and a scanning angle of 48° resulted in an optimized inspection of the entire joint.

Structure behavior of reinforced concrete beam-slab assemblies subjected to perimeter middle column removal scenario

The perimeter columns of framed structures are more vulnerable to terrorist attacks due to accessibility. The beams and slabs above the damaged columns are the primary structural members to redistribute gravity load to avoid progressive collapse. Therefore, to investigate the structural behavior of reinforced concrete (RC) beam-slab assemblies against progressive collapse introduced by a perimeter middle column removal scenario, an experimental program and numerical analyses were carried out in this paper. Three 3/10 scaled specimens, each of which consisted of two square slab panels and seven beams, were tested with equivalent uniformly distributed loading (UDL) achieved by a 12-loading apparatus. High-fidelity finite element models were used to conduct parametric studies after the validation, recheck the validity of the loading apparatus and highlight the effect of loading positions. The concerned parameters include the geometric parameters of beams caused by different seismic design intensity, the slab thickness and reinforcement ratio, and the type of reinforcing bars (i.e. deformed and plain). The results indicate that progressive collapse is resisted by compressive arch action and flexural action of the beams and slabs connecting the stub above the removed column at small deformation stage, whereas catenary action of longitudinal beams and tensile membrane action of slabs are more prevailing at large deformation stage. Moreover, higher seismic design intensity results in a larger resistance at small deformation stage, and plain bars cause larger deformation capacity. Finally, loading positions approaching the stub above the removed column tends to show smaller structural resistance.

A comparative analysis of three typical crash tests results based on small overlap frontal collision accidents

With the promotion of collision safety technical regulations, the vehicle safety technology has achieved a leap-forward development, and the occupants have been well protected in various collision conditions. However, the statistical data indicate that serious accidental casualties are still present in frontal collision traffic accidents with small overlap ratios. One of the main reasons is that vehicles in the small overlap collisions did not have the energy absorption effect of the longitudinal beams and body structure, causing serious deformation of the passenger compartment and injuries to the occupants. In this paper, the characteristics of small overlap accidents were analysed based on the China traffic accident database. Then, actual vehicle crash tests were carried out by adopting three typical small overlap crash test methods (vehicle-to-vehicle test method, IIHS test method and NHTSA test method), and in-depth analysis was conducted on the vehicle kinematics, collision strength (vehicle body acceleration and vehicle pulse index), occupant injuries, and vehicle body deformation in the crash tests. The results show that although the incidence of small overlap crash is low, the ratio of AIS3+ injury is very high, and the NTHSA test method is more similar to the vehicle-to-vehicle test than the IIHS test method.

Northam River Bridge, Southampton, UK: a life-extension maintenance project

The Northam River Bridge in Southampton, UK, carries the A3024 principal road across the River Itchen. The 1954 structure was a pioneer of early concrete post-tensioning techniques, with longitudinal prestressed beams held together both transversely and longitudinally with transverse post-tensioning. Works started in 2014 to address extensive water seepage that was potentially corroding post-tensioning elements. The need to avoid traffic disruption was a significant constraint in delivering the scheme. A post-tensioned special inspection to vulnerable details was undertaken when the main works contract started and a contraflow system was introduced. This revealed issues with the transverse tensioning that implied a need for reassessment. The outcome was that the majority of the structural elements were suitable for 40 t assessment live loading. However, there was a further requirement for measures to prevent any accidental wheel loading to the edge beams.

Hot stamping steel grades with increased tensile strength and ductility - MBW-K 1900, tribond 1200 and tribond 1400

The use of hot formed 22MnB5 steel with an aluminium-silicon (AS) coating is well established for high strength automotive parts to combine weight reduction and passenger safety. Recent developments aim to increase the material strength for further weight saving and to improve the ductility. Especially an improved ductility makes hot formed parts suitable for additional applications, such as parts with higher energy absorption or even axially loaded parts. thyssenkrupp Steel Europe AG has developed new hot stamping grades. With an increased strength of about 1900 MPa, the MBW-K 1900 allows the application of even lighter parts compared to 22MnB5. Due to the increased strength level, delayed fracture has to be evaluated. Furthermore, the recommended parameters for processing MBW-K 1900 are regarded.A high crash performance of a material implies a high strength, while the material still shows no cracking during folding or heavy bending of the automotive part. This is the basis for the development of tribond 1200 and tribond 1400. As a new concept for hot stamping, tribond 1200/1400 are composite materials, which bond two outer layers of a ductile 500 MPa steel grade with a high strength 1500 MPa steel core layer. Both grades are already well known as monolithic steels MBW 500 and MBW 1500 for hot stamping. An aluminium-silicon coating allows tribond 1200/1400 to be processed in the same way as AS coated 22MnB5. Nevertheless tribond 1200/1400 show a reduced susceptibility to hydrogen embrittlement in the 4-point bending test compared to 22MnB5. By their improved crash behaviour, tribond 1200/1400 enable the manufacturing of more kinds of hot formed parts such as longitudinal beams. An advanced simulation method takes the composite structure of tribond 1200/1400 into account to evaluate the crash behaviour.

Analysis of crack propagation in longitudinal beam of high- pile wharf during winter temperature decrease period

Ports play an increasingly important role in economic development and are the core strategic advantages that drive regional economic development. As hydraulic structure, the working environment of the wharf is relatively complicated. There are many factors affecting its normal use. Visible or invisible cracks are common in wharf components. Temperature stress change is the main factor for the formation of cracks on the surface of concrete beams. When affected by temperature changes, existing fine cracks will connect, expand, and even penetrate the entire component. It will not only affect the aesthetics of the wharf, but also affect its service life, and bring considerable economic losses to later maintenance. Therefore, it has certain reference value and significance to study on crack propagation for assessment of safety, reliability and durability of engineering structures. In view of this, this paper carries out numerical analysis on crack propagation of reinforced concrete longitudinal beams of a high-piled wharf in China with ABAQUS software and extended finite element method (XFEM). In the simulation process, only temperature drop factor is considered. At the same time, this paper introduces the research progress and some basic theories of XFEM at home and abroad. The results show that the numerical simulation results are similar to the crack opening degree measured by the seam gauge. XFEM can effectively describe the crack propagation in concrete, which is more accurate and feasible than the conventional finite element method (CFEM).

Static and stability analyses of pretensioned latticed arch frame with integrated cable-strut arrangement

Abstract For the latticed arch frame, a new type of integrated cable-strut arrangement is proposed. The comparison analysis on the static property and stability of the new-type pretensioned latticed arch frame with the traditional ones is conducted. The rational values of the arrangement parameters of the integrated cable-strut system, such as the strut location, cable sag, intersection position of the oblique cables, and the cable pretension ratio, are obtained by optimization analysis. Also, the analysis on configuration parameters of the pretensioned latticed arch frame, such as the ratio of rise to span, latticed column height, and the cross-sectional height of the latticed arch, is investigated. Moreover, the stability of the integral structure consisting of multiple parallel pretensioned latticed arch frames with integrated cable-strut system is studied in detail. The results indicate that the vertical and lateral stiffness of the latticed arch frame can be enhanced effectively by adopting the integrated cable-strut arrangement, and thus the static property and stability can be improved significantly. The effect of the pretensioned cable-strut system on improving the structural performance increases with increase of the latticed column height gradually, but it declines with increase of the cross-sectional height of latticed arch. The buckling mode of the integral structure depends on the number of the middle longitudinal latticed 3D beams.

Stochastic seismic lateral deformation of a multi-story subway station structure based on the probability density evolution method

Effective utilization of urban underground space has seen multi-story subway station structures become increasingly common. Two significant issues need to be solved in seismic evaluation of this kind of station structure. One is to set the appropriate seismic performance evaluation index; another is to choose a comprehensive method that can evaluate the structure performance with regard to the index. In this paper, a numerical model was established and validated by previously conducted shaking-table tests. Then stochastic seismic analyses were performed on the model using the probability density evolution method (PDEM). Inter-story drift and column drift ratio, which can reflect the lateral deformation of station structures induced by earthquake, were selected as seismic performance evaluation indexes and studied from the stochastic view. The stochastic analysis showed that the probability density distribution of the inter-story drift extremum of the middle-stories of the structure is larger than that of the top story and bottom story, similar to the lateral deformation mode of a ground frame structure with strong columns and weak beams. In addition, the probability density distribution of the column drift ratio extremum in each story is quite similar, and the probability density distribution of the column drift ratio extremum is larger than the inter-story drift extremum of the corresponding story. Compared with the inter-story drift, the column drift ratio is more suitable for evaluating the seismic performance of the multi-story subway station structure, because it reflects the influence of longitudinal beams with different height at the two ends of column on the lateral deformation of columns, which are key components and determine the safety of the structure to a great extent. By comparing the results of the PDEM with the shaking-table test, we found that stochastic analysis method can further obtain the probability of each numerical value of seismic performance evaluation indexes, thus making the evaluation results more comprehensive.

Design and Research of the Bending Test Set-up for the Longitudinal Joints in Segmental Tunnel Linings

As a weak link of the segmental lining ring in the shield tunnel, joints are main reasons for large deformation which further lead to various diseases during the tunnel construction and operation. These diseases, including water leakage, dislocation, joint opening, concrete crack etc., are detrimental to the safety and durability of the tunnel structure. In order to better understand the mechanical behaviour of joints, especially the longitudinal joints, much more attention have been paid to carry out corresponding experimental study. However, the design of the test-up is rarely covered in a lot of literature, which is also a critical factor for a successful experiment. In this paper, a test-up used for experimental study of the longitudinal joints in segmental tunnel rings was designed and executed in detail. The test device met both the test site requirements of the Building Structure Laboratory of Tongji University and the bearing capacity requirements under the maximum test load. After calculating the maximum horizontal and vertical test loads, the design of the test device system was completed. The setup included a short column, transverse and longitudinal loading beams, hinge supports, segment sleeves, supporting platforms and pillars. The test device can realize bidirectional loading and meet the requirement of large deformation of the test members during the test, which can provide a reference for the design of similar or even more sophisticated segmental joint test devices in the future.

Ensuring the reliability of the results of computer modeling of the behavior of bridge structures

It is noted that structural mechanics is developing in the direction of improving design schemes, allowing more correctly assess the stress-strain state of structures. One of the topical areas of improvement is the consideration of nonlinear behavior and spatial work of structures. Constructive and genetic nonlinearities are added to the geometric and physical. Attention is drawn to the problem of checking the correctness of design decisions, which are not always based on existing standards, but are justified by calculations of more correct, but also more complex calculation schemes, performed using powerful software systems. To solve this problem, the Glavgosexpertiza recommended making calculations for at least two certified, independently developed and tested in practice software systems, and conducting a comparative analysis of the results. The question that arose about which software systems to use, it is proposed to solve with the help of MIDAS/CIVIL (South Korea) and SOFISTIK (Germany) complexes that have proven themselves quite well in bridge organizations. The article provides a comparative analysis of the MIDAS/CIVIL and SOFISTIK software packages using the spatial calculation of a bridge structure as an example, and the results are also compared with the calculation using the standard methodology. For analysis, the span structure of the railway bridge was adopted, consisting of two main split trusses with a bottom ride, reinforced with longitudinal and transverse beams in the level of movement of the railway load, longitudinal and transverse ties combining the upper and lower truss belts. The main trusses of the diagonal system are reinforced with vertical struts and suspensions. In general, analysis of the calculation results shows that both software systems give fairly close values of the calculated values of forces and stresses, and the differences for individual elements do not exceed 13.90 %. The normative calculation method provides mainly overestimated in comparison with SOFISTIK PC results, and the excess can reach 53.73 % for longitudinal forces and 49.71 % for normal stresses. This difference is a consequence of the use of a flat design scheme in the regulatory methodology, which leads to an increase in the level of the acting longitudinal forces, transverse forces and bending moments. That is, the normative calculation for a number of elements of a bridge structure is, as it were, a margin of safety. In conclusion, the requirements are formulated for specialists involved in the calculation analysis and examination of project documentation.

Bio-Inspired Shape-Adaptive Soft Robotic Grippers Augmented with Electroadhesion Functionality.

Soft robotic grippers (SRGs) have been extensively employed in robotic grasping and manipulation applications due to the fact that they are beneficial for pick-and-place of difficult-to-handle and delicate objects with various geometries and stiffness in a comfortable and safer way. This article presents a bio-inspired and shape-adaptive SRG augmented with electroadhesion (EA) functionality, FinEA, by a cost-effective combination of a Fin Ray structured two-fingered SRG with two soft-stretchable EA pads. The EA pads were manufactured by screen printing a layer of electrically conductive and elastomeric carbon black powder mixed with polydimethylsiloxane onto a dielectric substrate. The compliant Fin Ray fingers, composed of soft longitudinal beams and rigid cross beams, were structurally optimized by the finite element method using ABAQUS/CAE based on three key parameters: the open angle of the longitudinal beams, the spacing between the cross beams, and the incline angle of the cross beams. The soft beams were produced by a traditional soft lithography method, whereas the rigid cross beams were three-dimensionally printed. The resultant FinEA grippers were capable of lifting not only flat/thin materials without distorting them due to the employment of EA, but also concave and convex objects due to the passively shape-adaptive Fin Ray structure and the EA functionality. In addition, the proposed FinEA grippers were able to grasp delicate materials and objects whose diameters are larger than the overall gripper length. Furthermore, 65% more weight in shear were picked up by the FinEA gripper when 4 kV was applied compared with 0 V. The FinEA concept provides useful and alternative solution for controllable adhesion-based SRGs and may facilitate the inspiration and development of future SRGs with added functionality and enhanced versatility.

Numerical analysis of a soil-steel bridge during backfilling using various shell models

Soil-steel bridges are becoming increasingly popular in various parts of the world, and are often built with a span of 3–25 m. Those with a span greater than 12 m are usually equipped with additional stiffening elements, e.g. ribs, relieving slabs, longitudinal beams, steel ribs and steel ribs filled with concrete. This paper examines the necessity of using these additional stiffening elements, using the example of a soil-steel bridge with a span of over 17 m. Stiffening steel ribs filled with concrete were used in this bridge, and the behaviour of the corrugated steel shell of the bridge was then analysed under backfilling loads. The DIANA program with the finite element method was used for the numerical analysis. The maximum displacements, bending moments and axial forces for the three numerical models of corrugated steel shell were considered, and the displacements obtained from numerical calculations were compared with measured results. In addition, the bending moments and axial forces obtained using finite element analysis were compared with results based on the relevant standards and design methods.

Design and Optimization of a New Hollow Circular Flexure Hinge for Precision Mechanisms

Flexure hinges have been used in many precision mechanisms where repeatable, friction free motion and high precision are required. Many kinds of flexure profiles have been proposed during the past decade. This paper presents a new type of flexure hinge which combines circular longitudinal axis beams to form hollow joint. This novel design will help to improve the range of motion, reduce stress level and increase the maximum load before yielding. Due to its special design, the cavity inside the hinge can also be filled with an elastomeric filler material to provide vibration damping. In order to synthesis this hinge, shape optimization integrating genetic algorithm and response surface methodology is used. The optimization procedure is programmed in MATLAB whereas finite element analysis in ANSYS is also embedded into the codes to enhance the calculation process. The new flexure hollow hinge is compared to the conventional straight-axis solid hinges (circular, elliptical and corner-filleted flexure hinges) in terms of stiffness, rotational precision and stress levels. It is also supposed that this new design would increase the precision of the mechanism due to reducing the parasitic motion. Finite element analysis in ANSYS is used to verify for the viability of the design before it can be fabricated and tested.

Structural failure of old reinforced concrete river wharf

According to the archival documentation the river harbour wharf was constructed around 1912. The quay was divided into 6 separated segments with a length of 32.0 m each. The structure of the wharf consists of the reinforced concrete frames situated perpendicularly to the riverbed. At ground level, the frames are connected by a reinforced concrete deck and longitudinal beams, located along the side of the river and the quay. The frames are also connected along the riverside by the concrete cap situated at the top of the retaining wall made of prefabricated panels and embedded in the bottom of the river. That wall constitutes a direct strengthening and protection of the embankment against the influence of the flowing river water. Basing on the performed inventory inspections, material examination, structural calculations and hydro-geotechnical analyses, the main reasons for the failure of the reinforced concrete wharf of the Odra River were defined. They were: very poor technical condition of the structure, lack of stabilizing anchors at the level of the wharf structure frames, and sudden fluctuations in water level in the river and their impact on the structure of the wharf. Moreover, from a static point of view, the embankment under the wharf was in an unstable equilibrium and at any time it could be damaged if additional horizontal forces were applied to it. Additionally, the possible impact of anchoring to the piers of the wharf of two river barges on wharf structure capacity was also analyzed.

Multi-objective optimization of underground car park design for tenability under fire-induced smoke

The effects of the inclusion of design factors in optimization such as ceiling height, beam span length, transversal beam depth, longitudinal beam depth, and extraction fan rate on the tenability of car parks during fire were studied. Fire Dynamic Simulator (FDS) was employed as the simulation tool for response generation, from which the preliminary simulation results were firstly compared with published experimental data for validation. Responses such as smoke descent time, critical velocity, and temperature were optimized using the Response Surface Methodology (RSM). Thirty-two FDS models were constructed using the Central Composite Design (CCD) method and second-order models were formulated. The predicted responses from the second-order models were in good agreement with those obtained from FDS. In the optimized design, the smoke descent time was increased by 191.08% and the critical velocity was reduced by 61.67%. Meanwhile, the change of temperature was marginal. Moreover, by examining the flow result, the employment of two longitudinal beams from the optimized design could effectively channel the hot gasses to the downstream region. Overall, it was found that the presence of beams combined with the FDS statistical analysis could improve the tenability of enclosed car parks during fire.

Recommendations for the Construction and Strength Calculation of Upright Tanks for Sulfuric Acid Production

Recommendations for the construction and strength calculation of upright sulfuric acid tanks are given. An evaluation of the possibility of strength and stability calculations of tank shells in accordance with All-Russia State Standard 34233.2 and All-Russia State Standard 34283 is given. Relationships for calculating the thickness of the bottom wall and the rational distance between the longitudinal beams of the frame bottoms as functions of the sulfuric acid fill level (hydrostatic pressure) are presented.

Closed-form exact solutions for hysteretically damped longitudinal free and forced vibrations of tapered beams

Exact solutions for hysteretically damped free vibrations of tapered longitudinal beams are obtained instead of undamped free vibrations. Also forced vibrations of tapered longitudinal beams with hysteretical damping are studied by a closed-form exact method. The hysteretically damped natural frequency equations are exactly derived. Accurate longitudinal amplitude versus forcing frequency curves showing the forced response due to distributed loading are plotted with various hysteretical damping parameters. The present method is capable to be applied to a tapered tall building with hysteretic damping subjected to longitudinal harmonic loads like earthquake loads.

Problems and innovative solutions considering “open type” bridge deck structures in old steel riveted railway bridges

There are 331 steel bridges with total length 11201,70m in exploitation in the railway infrastructure of the Republic of Bulgaria. Significant part of those bridges is with “open type” deck including longitudinal and cross beams. The stress state of a standard bridge deck of an old steel riveted truss bridge along Sofia - Varna railway line at km 17 + 536 (representing wide class of bridges in exploitation) is analysed in this paper in accordance with the prescriptions of the Eurocode design standard. Results, obtained from different FEM (with Frame and Shell elements) indicate that the load bearing capacity of longitudinal and cross beams is significantly insufficient, which is due to increased loads and some specificity of the construction details. On the other hand there is an overage of load bearing capacity for the elements of the main truss and the effect of an innovative concept for replacement of the existing “open type” deck with new reinforced concrete plate is investigated and analyzed.