Mechanical performance of shear studs and application in steel-concrete composite beams

This work experimentally investigates the effects of shear stud characteristics on the interface slippage of steel-concrete composite push-out specimens. ABAQUS is used to establish a detailed 3D finite element(FE) model and analyze the behavior of push-out specimens. The modeling results are in good agreement with the experimental results. Based on parametrical analysis using the validated FE approaches, the effects of important design parameters, such as the diameter, number, length to diameter ratio, and yield strength of studs, concrete strength and steel transverse reinforcement ratio, on the load-slip relationship at the interface of composite beams are discussed. In addition, a simplified approach to model studs is developed using virtual springs with an equivalent stiffness. This approach is demonstrated to be able to predict the load-displacement response and ultimate bearing capacity of steel-concrete composite beams. The predicted results show satisfactory agreement with experimental results from the literature.

Hybrid Optimization Based PID Controller Design for Unstable System

PID controllers play an important function in determining tuning para-meters in any process sector to deliver optimal and resilient performance for non-linear,stable and unstable processes.The effectiveness of the presented hybrid metaheuristic algorithms for a class of time-delayed unstable systems is described in this study when applicable to the problems of PID controller and Smith PID controller.The Direct Multi Search(DMS)algorithm is utilised in this research to combine the local search ability of global heuristic algorithms to tune a PID controller for a time-delayed unstable process model.A Metaheuristics Algorithm such as,SA(Simulated Annealing),MBBO(Modified Biogeography Based Opti-mization),BBO(Biogeography Based Optimization),PBIL(Population Based Incremental Learning),ES(Evolution Strategy),StudGA(Stud Genetic Algo-rithms),PSO(Particle Swarm Optimization),StudGA(Stud Genetic Algorithms),ES(Evolution Strategy),PSO(Particle Swarm Optimization)and ACO(Ant Col-ony Optimization)are used to tune the PID controller and Smith predictor design.The effectiveness of the suggested algorithms DMS-SA,DMS-BBO,DMS-MBBO,DMS-PBIL,DMS-StudGA,DMS-ES,DMS-ACO,and DMS-PSO for a class of dead-time structures employing PID controller and Smith predictor design controllers is illustrated using unit step set point response.When compared to other optimizations,the suggested hybrid metaheuristics approach improves the time response analysis when extended to the problem of smith predictor and PID controller designed tuning.

Effect of Different Connectors on Concrete Composite Box-Girders with Corrugated Steel Webs

In order to resolve affecting of Different Shear Connectors(the perfobond leisten(PBL) shear connectors and stud shear connectors) on the M echanical Properties of Prestressed Concrete Composite BoxGirders with Corrugated Steel Webs,Some mechanical properties of Prestressed Concrete Composite BoxGirder with Corrugated Steel Webs were researched by conducting experiments on two specimens with PBL shear connectors and stud shear connectors relating to ultimate bearing capacity,the flexural stiffness,crack resistance properties and the efficiency of prestressing being introduced to the girder,etc. The test results show ed that,relative to the stud shear connectors,PBL shear connectors can greatly improve some structural performance qualities of prestressed concrete composite box-girders with corrugated steel webs,such as the ultimate bearing capacity,the flexural stiffness and the crack resistance property,but when the efficiency of prestressing is introduced into the girder,the PBL shear connectors do not perform as well as stud shear connectors.

In-Plane Shear Performance of Wood-Framed Drywall Sheathing Wall Systems under Cyclic Racking Loading

A pilot study was conducted at Penn State University to determine whether the type of drywall joint compound would influence the shear strength of wood-frame stud walls sheathed with Gypsum Wall Board (GWB or drywall). In this study, five 2438 mm by 2438 mm specimens were tested under in-plane cyclic racking loading following the CUREE loading protocol for light-frame wall systems. Three specimens were finished using non-cement based joint compound while the other two used cement based joint compound. Based on the experimental testing of the specimens, the results show that the use of cement based joint compound on drywall joints produces higher shear capacity for the wall system as compared to similar specimens finished with conventional non-cement based joint compound. The result of the study is particularly important for high seismic regions where interior stud walls in residential construction effectively take part in seismic resistance even though wood shear walls are normally used on exterior walls.

Microstructure characteristics and mechanical properties of steel stud to Al alloy by CMT welding-brazing process

Cold metal transfer （CMT） welding of nickel-coated Q235 steel studs with 606l Al alloy was carried out using ER4043 as filler metal. The welding process was stable, and appearance of weld formed well without surface defect under the parameters of welding current 121 A, welding voltage 15.4 V and welding speed 6 r/min. The microstructure of fiUer metal was analyzed by means of scanning electron microscopy. The filler metal and 6061 Al alloy were fused to form fusion welding interface, the fusion zone had a good bonding without any micro defect. The steel stud did not melt and brazing interface was formed between the filler metal and steel stud. Two different reaction layers existed in the brazing interface, the Fe2Al5 layer about 10 -12 p^m formed near the steel stud side, and the other layer was mainly composed of FeAl3. Nickel-rich zone was formed in the root toe area of the fillet weld, which was mainly composed of Al3Ni2. The tensile tests showed that the maximum shearing strength of the joints was 129 MPa. The joint was brittle fractured in the intermetallic compound layer where plenty of FeAl3 were distributed continuously.

Internal Force Distribution in Steel-Concrete Composite Structure for Pylon of Cable-Stayed Bridge

Adopting a steel-anchor beam and steel corbel composite structure in the anchor zone on pylon is one of the key techniques for the design of Jintang bridge, a cable-stayed bridge in Zhoushan, China. In order to ensure the safety of the steel-concrete composite structure, a stud connector model for the joint section was put forward. Experiments were conducted to obtain the relation between load and slip of specimen, the failure pattern of stud connector, the yield bearing capacity and ultimate bearing capacity of a single stud, etc. The whole process of the structural behavior of the specimen was comprehensively analyzed. The features of the internal force distribution in the steel-concrete composite structure and the strain distribution of stud connector under different loads were emphatically studied. The test results show that the stud connector is applicable for the steel-concrete composite structure for pylon of Jintang bridge. The stud has a good ductility performance and a obvious yield process before its destruction. The stud connector basically works in a state of elasticity under a load less than the yield load.

Investigation on the stepping arc stud welding process

Through the investigation on traditional arc stud welding process, a new welding gun and its control system were developed in this paper. The stepping arc stud welding gun was mainly made by a stepping motor as actuating unit and a screw-driven device as moving unit. A control system with a MCS-51 single-chip microcomputer as main control component was used to realize the new stud welding procedure. This new welding process with stepping stud welding gun is named as stepping arc stud welding. In the new welding process, the stud action can be looked as constituted by some micro steps. The setting and adjusting of the stepping arc welding gun behavior parameters are accomplished independently. It is indicated from the results of process tests and bending test that the stepping arc stud welding process is practicable.

Nickel-coated Steel Stud to Aluminum Alloy Joints Made by High Frequency Induction Brazing

Nickel-coated 45 steel studs and 6061 aluminum alloy with 4047 A1 alloy foil as filler metal were joined by using high frequency induction brazing. The microstrueture of Fe/A1 brazed joint was studied by means of optical microscopy （OM）, scanning electron microscope （SEM）, energy dispersive X-ray （EDX）, and X-ray diffraction （XRD）. Results showed that 45 steel stud and 6061 aluminum alloy could be successfully joined by high frequency induction brazing with proper processing parameters. The bonding strength of the joint was of the order of 88 MPa. Ni coating on steel stud successfully avoided the generation of Fe-AI intermetallic compound which is brittle by blocking the contact between A1 and Fe. Intermetallic compounds, i e, AI3Ni2, AlmNi0.9 and A10.3Fe3Si0.7 presented in AI side, FeNi and Fe-A1-Ni ternary eutectic structure were formed in Fe side. The micro-hardness in intermetallic compound layer was 313 HV. The joint was brittle fractured in the intermetallic compounds layer of A1 side, where plenty of A13Ni2 intermetallie compounds were distributed continuously.

Stud Pose Detection Based on Photometric Stereo and Lightweight YOLOv4

There are hundreds of welded studs in a car.The posture of a welded stud determines the quality of the body assembly,thus affecting the safety of cars.It is crucial to detect the posture of the welded studs.Considering the lack of accurate method in detecting the position of welded studs,this paper aims to detect the weld stud’s pose based on photometric stereo and neural network.Firstly,a machine vision-based stud dataset collection system is built to achieve the stud dataset labelling automatically.Secondly,photometric stereo algorithm is applied to estimate the stud normal map which as input is fed to neural network.Finally,we improve a lightweight YOLOv4 neural network which is applied to achieve the detection of stud position,thus overcoming the shortcomings of traditional testing methods.The research and experimental results show that the stud pose detection system designed achieves rapid detection and high accuracy positioning of the stud.This research provides the foundation combining the photometric stereo and deep learning for object detection in industrial production.

Current waveforms and sequence control system of microprocessor-controlled short cycle stud welding converter

The applied conditions of stud welding on body of automobile, and the current waveforms and sequence control techniques which are set to meet the quality of stud welding in the car body, are introduced in this paper. The realizing method of current waveforms and sequence control based on microprocessor are also discussed in detail. The waveforms of output welding current and voltage are measured. It is proved that the techniques including current waveforms & sequence control can successfully meet the demand of automobile stud welding.

Double⁃Shear Experiments of Cold⁃Formed Steel Stud⁃to⁃Sheathing Connections at Elevated Temperatures

The behavior of cold⁃formed steel(CFS)stud⁃to⁃sheathing connections at elevated temperatures is an important parameter for the fire resistance design and modeling of mid⁃rise CFS structures.In this paper,three kinds of sheathings,namely,medium⁃and low⁃density calcium⁃silicate boards and oriented strand board,were selected for double⁃shear experiments on the mechanical properties of 253 screw connections at ambient and elevated temperatures.The effects of the shear direction,screw edge distance and the number of screws on the behavior of the connections were studied.The results showed that the shear direction and the screw edge distance more significantly influenced the peak deformation,while their impacts on the peak load varied with the type of sheathings.Compared with the single⁃screw connections,the peak loads of the specimens with double⁃screw connections obviously increased but did not double.Finally,a simplified load⁃displacement curve model of stud⁃to⁃sheathing connections at elevated temperature was generated first by establishing the prediction formula for characteristic parameters,such as the peak load,the peak deformation and the elastic stiffness,and then by considering whether the curves corresponded to stiffness increase phenomena.The present investigation provides basic data for future studies on the numerical modeling of CFS structures under fire conditions.

联邦德国带端头锚杆(Stud)的新设计方法及算例

结合梁中采用带端头的锚杆作为联结件已很普遍。最近联邦德国根据试验研究对此建立起在受拉、受剪和剪拉组合等外力作用下的计算方法,规定了锚杆边距、中距以及锚固在受拉区或受压区,锚杆群等因素对承载力的影响,较以往的设计方法有所改进。本文所介绍的这一方法已得到联邦德国政府建设技术院审定批准,文末附有简明的设计算例。

Performance of a Panelized Brick Veneer Wall System under Lateral Loads

This paper discusses the performance of a proposed panelized brick veneer over steel stud backup wall system and seismic isolation connections under lateral loads. The panelized wall system was developed to address some shortcomings of the conventional brick veneer wall type. The details of the system are briefly introduced. The study evaluated the performance of the system under out-of-plane simulated wind loads and in-plane cyclic loads using full-scale laboratory experiments. The test setup, test specimen, test procedure, and test results are presented and the performance of the system is evaluated accordingly.

Home Studìo(三)

Track 4音频软件 前面说完了硬件,这次当然就是要说说软件了. 经常用到的音频软件,笔者的观点可以将其分为以下几类(可能不是太科学):多轨音频软件、wav编辑软件、效果器插件、软音源(软采样器)以及各种其它的周边工具软件.严格地说软音源应该算在MIDI软件之中;还有一些集大成者被称作音频工作站软件,不仅上面提到的几类软件功能通通囊括,还有强大的MIDI音序器功能(即录制/编辑MIDI文件),甚至还可以刻录CD,可算是音乐软件里的航空母舰了. 废话就不多说了,还是让我们走近些来看仔细吧.

Dragon Brand Steel Stud

The Dragon Brand light steel stud used for partition is a kind of metallic framework that is continuously milled and rolled with cold formed steel shape using a cold-worked steel plate or strip, or zinc-coated plate or strip, or coloured plastic packing steel plate, as materials. The steel stud has the features of light weight, high tension and anti-erosion. It can be used as light partition material together with plaster board, and its products or with other board materials such as GRC boards or

Attempt to improve Vocabulary Teaching for Higher Vocational College Students

Vocabulary is the building material of language,and vocabulary study is therefore one of the most important aspects in any language learning.It is a key point to improve English learning through paying more attention to vocabulary acquisition.However,vocabulary teaching is one aspect of language teaching that has not been given enough attention in China.Therefore,some issues in vocabulary teaching and learning in higher vocational colleges are being addressed at present,which are worthy of our further consideration.

Behavior and strength of headed stud shear connectors in ultra-high performance concrete of composite bridges

This study presents an experimental and numerical investigation on the static behavior of headed stud shear connectors in ultra-high performance concrete (UHPC) of composite bridges. Four push-out specimens were tested. It was found that no cracking, crushing or splitting was observed on the concrete slab, indicating that UHPC slab exhibited good performance and could resist the high force transferred from the headed studs. The numerical and experimental results indicated that the shear capacity is supposed to be composed of two parts stud shank shear contribution and concrete wedge block shear contribution. The stiffness increment of a stud in UHPC was at least 60% higher than that in normal strength concrete. Even if the stud height was reduced from 6d to 2d, there was no reduction in the shear strength of a stud. Short stud shear connectors with an aspect ratio as small as 2 could develop full strength in UHPC slabs. An empirical load-slip equation taking into account stud diameter was proposed to predict the load-slip response of a stud. The reliability and accuracy of the proposed load-slip equation was verified by the experimental and numerical load-slip curves.

Evaluating Anti-SmDl-amino-acid 83-119 Peptide Reactivity in Children with Systemic Lupus Erythematosus and Other Immunological Diseases

Background： SmD1-amino-acid 83-119 peptide （SmD183-119） is the major epitope of Smith （Sm） antigen, which is specific for adult systemic lupus erythematosus （SLE）. The anti-SmD183-119 antibody has exhibited higher sensitivity and specificity than anti-Sm antibody in diagnosing adult SLE. However, the utility of anti-SmD183-119 antibodies remains unclear in children with SLE （cSLE）. This study aimed to assess the characteristics of anti-StuD 183-119 antibody in the diagnosis of cSLE. Methods： Samples from 242 children with different rheumatological and immunological disorders, including autoimmune diseases （SLE [n = 46] and ankylosing spondylitis [AS, n = 11]）, nonautoimmune diseases （Henoch-Schonlein purpura [HSP, n = 60], idiopathic thrombocytopenia purpura [n = 27], hematuria [n = 59], and arthralgia [n = 39]） were collected from Shanghai Children＇s Medical Center from March 6, 2012 to February 27, 2014. Seventy age- and sex-matched patients were enrolled in this study as the negative controls. All the patients＇ sera were analyzed for the anti-SmD 183-119, anti-Sm, anti-U 1-nRNP, anti-double-stranded DNA （dsDNA）, anti-nucleosome, anti-SSA/Ro60, anti-SSA/Ro52, anti-SSB, anti-Scl-70, and anti-histone antibodies using the immunoblotting assay. The differences in sensitivity and specificity between anti-SmD183-119 and anti-Sm antibodies were compared by Chi-square test. The correlations between anti-SmD183-119 and other auto-antibodies were analyzed using the Spearman＇s correlation analysis. A value of P 〈 0.05 was considered statistically significant. Results： Thirty-six out of 46 patients with cSLE were found to be positive for anti-SmD183-119, while 12 patients from the cSLE cohort were found to be positive for anti-Sm. Compared to cSLE, it has been shown that anti-SmD183-119 was only detected in 27.3% of patients with AS and 16.7% of patients with HSP. In comparison with anti-Sm, it has been demonstrated that anti-StuD 183-119 had a higher sensitivity （78.3% vs. 26.1%, 2＇2 = 25.1, P 〈 0.05） and a lower specificity （90.8% vs. 100%, x^2 = 13.6, P 〈 0.05） in the diagnosis of cSLE. Further analysis revealed that anti-StuD 183-119 antibodies were positively correlated with anti-dsDNA, anti-nucleosome, and anti-histone antibodies in cSLE. Moreover, it has been clearly shown that anti-SmD183-119was more sensitive than anti-Sm in discriminating autoimmune diseases from nonautoimmune disorders in patients with arthralgia or hematuria. Conclusions： Measurement of anti-SmD183-119 in patients with cSLE has a higher sensitivity and a marginally lower specificity than anti-Sin. It has been suggested that inclusion of anti-SmD183-119 testing in the integrated laboratory diagnosis ofcSLE may significantly improve the overall sensitivity in child populations.

A review of the metal stud stiffness on the sound insulation of gypsum-board partitions

For the sound insulation of a double-panel partition,the stud between two leaves creates a vibration transmission path,which can often be more critical and more important in the mid-frequency range than the airborne path through the cavity.Owing to the fact that partitions with light-weight steel studs are commonly used in building construction,studies on the sound insulation effect of such studs have been conducted.Especially,a model,initiated by Gu and Wang(1983),has been widely studied during the past decades.In the model,the steel stud is considered as an elastic spring with its cross-section stiffness in the sound insulation index prediction of such a partition.Experimental results of different stud profiles have been reported from different testing laboratories and more information has been gained to understand the stiffness effect of the stud on the sound insulation of the double-leaf partitions.In this paper,the authors have given this subject a thorough review and have concluded that a critical problem needs further investigation on the determination of the stiffness of the connecting elements in the double-leaf partitions.

Study on the interfacial shear behavior of steel reinforced concrete （SRC） members with stud connectors after fire

Statically push-out tests of 20 steel reinforced concrete short columns （SRCSC） with stud connectors on the surface of shape steel after fire and two SRCSC under ambient temperature were carried out, in order to study the failure mode, load-slip relationship and the interfacial shear transfer of SRC members after fire. Experimental results show that the typical failure modes and load-slip curves of SRCSC after fire are almost the same as the case under ambient temperature. The interfacial shear transfer of SRCSC declines exponentially not only with the increase of the peak temperature the specimen experienced but also with the increase of the peak temperature duration. The interfacial shear transfer of the specimens with studs arranged at the steel web is much higher than those with studs arranged at the steel flange. Empirical formulas of SRCSC interfacial shear transfer after fire are proposed, and the calculated results generally agree well with the experimental results.