Horizontal Joints Research Articles

The stress-strain state of horizontal joints of wall panels

The article is devoted to the experimental and numerical research of the stress-strain state of wall panels joints from foam concrete of natural hardening. The eccentricity of the load and the quantity of indirect reinforcement meshes are adopted as factors that have a significant effect on the stress-strain state of the joint elements. The load in the experimental research and numerical simulation was applied in steps of 0.1 of the estimated value of the destructive force. Numerical modelling was carried out with consideration of the physical nonlinearity of the wall panel materials. A significant increment in the displacement of the design scheme nodes at the current loading stage was taken as a destruction criterion in numerical modelling. It is noted that the installation of indirect reinforcement meshes leads to a reduction of transverse deformations of the wall panel, but does not significantly affect the bearing capacity of the joint.

ИССЛЕДОВАНИЕ СПОСОБОВ РЕМОНТА ЛИЦЕВОЙ КИРПИЧНОЙ КЛАДКИ МНОГОСЛОЙНЫХ СТЕН

This article discusses the methods of repairing the brick facing layer of multilayer walls: repair and restoration of vertical and horizontal expansion joints; use when strengthening repair connections and anchor connections; injection and re-inforcement of cracks; Fibre Reinforced Cementitious Matrix and direct repair of brickwork. The conclusion is made about the importance of choosing the right method of repair and the factors affecting it.

Numerical and experimental investigation on weld formation during laser+MIG hybrid fillet welding of aluminum alloy in horizontal position

A three-dimensional transient model is proposed to investigate the weld formation during laser + metal inert gas (MIG) hybrid welding of aluminum alloy for horizontal fillet joint, which considers the coupling of keyhole, droplet, and liquid metal pool as well as the influence of joint geometry feature and welding position. An asymmetrical double-elliptic heat source is utilized to model the arc heat input and a conic heat source with increased peak heat density is used to describe the laser energy. The coordinate rotation is used to take into account the inclination of heat source and the related forces. According to the experimental and simulated results, weld formation mechanism of horizontal fillet joint is studied. At a lower laser power, the fluid flow pattern in hybrid welding is similar to that in MIG welding and a strong downward flow caused by both gravity and arc pressure occurs at the liquid metal zone of the vertical plate, leading to the accumulation of molten metal at the horizontal plate and the resultant weld asymmetry. At high laser power, a clockwise vortex appears above the keyhole. In this case, the sagging of liquid metal near weld pool surface due to effect of gravity is an important factor responsible for the asymmetry of fillet weld. Besides, with increasing laser power, the tendency of weld pool free surface sagging is enhanced to some extent and weld bead surface becomes concave.

Ultrasound of horizontal instability of the acromioclavicular joint : Asimple and reliable test based on acadaveric study.

SummaryBackgroundHorizontal instability influences the clinical outcome after acromioclavicular joint (ACJ) injuries and in joint degeneration. A standardized, dynamic examination of the horizontal instability has not been described before. This current study presents a sonographic method to analyze the dynamics between the clavicle and acromion in the horizontal plane.MethodsThe horizontal joint play, the ACJ space and the offset between clavicle and acromion were sonographically assessed by a 45° ventrally angulated longitudinal section. A total of four investigators with different experience in the field of musculoskeletal ultrasound examining 20 ACJs in 10 human cadavers. Measurements in the absence of any pressure and under standardized anterior and posterior pressure onto the clavicle were carried out in different ligament status intact acromioclavicular (AC) and coracoclavicular (CC) ligaments as well as in a Rockwood (RW) II and III model. A two-sided t‑test was used to examine the differences between joint positions and ligament status.ResultsThe horizontal joint play was 1.3 ± 0.9 mm with intact ligaments, 1.4 ± 1.2 mm by transecting the AC ligaments and 1.9 ± 1.3 mm after additionally transecting the CC ligament. The joint space was 3.3 ± 1.1 mm with intact ligaments, 4.1 ± 1.8 mm in an iatrogenic RW 2 injury, and 5.3 ± 3.3 mm in an iatrogenic RW 3 injury. Manipulating the clavicle by applying anterior or posterior pressure did not change the difference within one injury pattern. Interobserver reliability was 83.9%.ConclusionApart from evaluating the ligaments and the joint capsule, measurement of the dynamic horizontal instability is possible in a human cadaver model. The ultrasound-based measurement of horizontal instability dynamics avoids radiation exposure, is readily available and cost-efficient.

Shear behavior of non-persistent joints in concrete and gypsum specimens using combined experimental and numerical approaches

In this paper, shear behavior of non-persistent joint surrounded in concrete and gypsum layers has been investigated using experimental test and numerical simulation. Two types of mixture were prepared for this study. The first type consists of water and gypsum that were mixed with a ratio of water/gypsum of 0.6. The second type of mixture, water, sand and cement were mixed with a ratio of 27%, 33% and 40% by weight. Shear behavior of a non-persistent joint embedded in these specimens is studied. Physical models consisting of two edge concrete layers with dimensions of 160 mm by 130 mm by 60 mm and one internal gypsum layer with the dimension of 16 mm by 13 mm by 6 mm were made. Two horizontal edge joints were embedded in concrete beams and one angled joint was created in gypsum layer. Several analyses with joints with angles of 0o, 30o, and 60o degree were conducted. The central fault places in 3 different positions. Along the edge joints, 1.5 cm vertically far from the edge joint face and 3 cm vertically far from the edge joint face. All samples were tested in compression using a universal loading machine and the shear load was induced because of the specimen geometry. Concurrent with the experiments, the extended finite element method (XFEM) was employed to analyze the fracture processes occurring in a non-persistent joint embedded in concrete and gypsum layers using Abaqus, a finite element software platform. The failure pattern of non-persistent cracks (faults) was found to be affected mostly by the central crack and its configuration and the shear strength was found to be related to the failure pattern. Comparison between experimental and corresponding numerical results showed a great agreement. XFEM was found as a capable tool for investigating the fracturing mechanism of rock specimens with non-persistent joint.

The consideration of compliance of structural joints in calculation of large panel buildings

The article presents and analyzes the design solutions of horizontal and vertical joints, as well as methods for determining the coefficient of compliance joints. It also presents the numerical determination of the coefficients of compliance of the horizontal mortar joint in accordance with the standards for the design of large-panel buildings. It is shown that the compliance of the joint on the embedded parts consists of the compliance of the connecting element, embedded parts of the wall panels, namely the metal plate and reinforcing bars of the anchors, as well as the compliance of the welds. In this case, the joint operates in a complex stress-strain state. It is noted that the most difficult is to determine the compliance of embedded parts. Three calculation methods have been developed for the numerical determination of the compliance coefficients of anchor bars under the action of tension (compression), bending moment and shear forces on the embedded part. The deformation of the welds was defined in MGSU in the framework of the experimental research of the work of the vertical seam with embedded parts. The article presents a graph of the deformation in the weld on the applied vertical load on the test piece.

Compressive performance of new types of load-bearing horizontal-hole interlocking concrete hollow blocks

Two series of load-bearing horizontal-hole interlocking hollow concrete blocks, referred to as H-shaped series and cross-shaped series, were developed, including three geometric types: type BH-290 (H-shaped), type BH-240 (H-shaped), and type BC-240 (cross-shaped). The research presented in this article investigated the compressive behavior of the proposed load-bearing horizontal-hole interlocking hollow concrete blocks and aimed at analyzing the influence of geometric parameters on the block capacity. First, compressive tests of the horizontal-hole interlocking hollow concrete blocks were carried out. The compressive strength, elastic modulus, and compressive failure mechanism were analyzed. Second, the feasibility of the finite element analysis model was verified by experimental results presented in this article, as well as by available test data from other researchers. The influences of vertical ribs, horizontal ribs, and concrete strength on the compressive strength of horizontal-hole interlocking hollow concrete blocks were investigated. Ultimately, based on the numerical modeling results, linear equations were proposed to predict the compressive strength of H-shaped series and cross-shaped series blocks. The results show that the compressive strengths of types BH-240, BH-290, and BC-240 are 15.9, 13.4, and 13.0 MPa, respectively. For the H-shaped series, the core horizontal rib is the key part that can significantly constrain the vertical ribs so that the block can achieve higher compressive bearing capacity. For the cross-shaped series, core horizontal ribs cannot improve the compressive strength of the block because core horizontal ribs and joints near them become damaged early. Improving the concrete strength and the width of the vertical rib can effectively improve the compressive bearing capacity for both H-shaped and cross-shaped series blocks. The accuracy of the proposed equations for predicting the compressive strength of H-shaped and cross-shaped blocks is acceptable, according to the current verification.

Reduce the Influence of Horizontal and Vertical Cold Joints on the Behavior of High Strength Concrete Beam Casting in Hot Weather by Using Sugar Molasses

The current research studies the effect of cold joints on the behavior shear and flexure of High Strength Concrete (HSC) beams caused by delayed casting sequence during the hot weather in summer of Iraq.Fresh concrete should be kept alive during the various casting batches for concrete element by re-vibration. However, the over vibration caused loss in homogeneity and it is difficult to keep the workability of concrete during hot weather due to the effect of setting time.To deal with this problem of improper casting sequence, which eventually leads to the formation of cold joints, it will be used sugar waste (named as Sugar Molasses (SM)) is a by-product resulted from refining process of sugar as a delayed agent to increase the setting time in order to prevent early set of concrete due to adverse effects in construction joint of hot weather.In the current study, the first objective aims to investigate some of fresh and hardened mechanical properties of HSC (with high cement content) using SM at percentages of (0, 0.05, 0.1, 0.2, 0.3) % from the weight of cement under the concept of sustainable development. The second objective aims to investigate the location and surface texture effect of horizontal and vertical cold joints on the flexural and shear behavior of beam with/without SM. This objective includes testing of twenty four plain concrete beam of (110×110×650 mm) under two point load; half of them casting without roughing (smooth) the old layer and the other casted after roughed it.SM content of 0.2% of cement weight can improve compressive strength by about 11.2% at 28 days and delay initial setting time by about 4.617 hours (277 minutes). No adverse effect on concrete have been observed at this dosage of SM concentration for the ages of concrete cylinders studied. Delays in the setting of concrete at this dosage of SM content help in reducing the early setting of concrete and therefore reduced the impact of the cold joints formation in concrete beams under Iraqi hot weather condition. The failure load for the beams with SM of smooth and rough vertical joints is in the range between (1.95 - 2.12) and (1.46-1.37); respectively times that of the case of beam without SM.

Assessment of the combined in‐plane and out‐of‐plane behavior of brick infill walls within reinforced concrete frames under seismic loading

SummaryUnderstanding the out‐of‐plane response of masonry infill walls and preventing their progressive collapse mechanisms is very important for earthquake‐prone countries to prevent loss of life and economic loss. In fact, having a realistic collapse mechanism assessment allows suitable prevention measures to be adopted. With this purpose in mind, two full‐scale one‐bay one‐story substructures of reinforced concrete frames (RCF) with infill walls were tested on a shake table. These 2 specimens were designed to represent the response of a typical RC Frame at the fifth floor of an 8‐story building, namely the out‐of‐plane failure of its infill wall under combined bidirectional seismic load. Both specimens were composed of a single‐leaf clay brick infill wall surrounded by the RC Frame. However, while the first specimen corresponds to an unreinforced masonry configuration, the second specimen includes horizontal bed joint reinforcement as a strengthening/retrofitting technique. The main novelty of this study is the application of a bidirectional and simultaneous dynamic loading to the specimen, such that in‐plane and out‐of‐plane effects are evaluated together. This work presents several interesting experimental results, with particular emphasis on the bearing capacity of the specimens against out‐of‐plane failure. As expected, the in‐plane capacity of the reinforced infill specimen is larger than that of the unreinforced infill specimen. Nevertheless, the out‐of‐plane bearing capacities of the two specimens are very similar, in contrast to their ductility capacity, which is significantly increased in the reinforced masonry specimen. The capacities of the two specimens for both in‐plane and out‐of‐plane directions, as predicted by formulations in the literature, are given. The differences found between these calculations and the results of the tests are discussed, and may possibly be explained by the parameters considered in the different formulations.

NZEBs built of elements based on styrofoam re-granulate

In the article there was introduced an idea of NZEB constructed from large size wall elements mounted with dry connection and horizontal joints filled with polyurethane mortar. The proposed element was 50 cm thick with set of layers made of styro-concrete with EPS re-granulate and EPS-032 separation layers. The result was a solution with high thermal isolation and traditional division for construction and isolation zones. Additional elements of the system are layered lintels and intermediate moldings with increased pressing strength. The material solutions of the system elements are the effect of combined construction and thermal analyses.

Reversed Cyclic Loading Test on Emulative Hybrid Precast Concrete Shear Walls under Different Vertical Loads

An experiment was carried out to investigate the seismic performance of hybrid precast concrete shear walls, which aimed to emulate the monolithic RC wall by incorporating unbonded post-tensioned high-strength strands and vertically connected reinforcing bars by grouting across the horizontal joint for lateral resistance. The unbonded tendons provided the pre-compression and the recentering force. The grouted reinforcing bars were used to provide the bending strength, reduce the gap opening size, and eliminate the horizontal slippage along the joint. Three full-scale emulative hybrid wall specimens under different vertical loads and one monolithic RC wall specimen for reference were subjected to reversed cyclic loading. The test results showed that, the emulative hybrid specimens, with vertical load less than or equal to that of the monolithic specimen, exhibited good lateral performance and the seismic properties, including strength, stiffness, ductility and energy dissipation, were comparable to that of the monolithic specimen. As the vertical load increased, the strength and stiffness were enhanced, however, the energy absorbing capacity was obviously decreased.

Dynamic instability of the acromioclavicular joint: Anew classification for acute AC joint separation.

BackgroundAcute acromioclavicular (AC) dislocation is classified according to Rockwood (RW). Although of clinical relevance, dynamic horizontal translation (DHT) is not listed in this classification or in frequently used clinical evaluation tools. The aim of this study was (a) to evaluate vertical and horizontal AC joint instabilities and assess their combined occurrence and clinical appearance in a consecutive group of patients, as well as (b) to develop a new classification of acute AC joint dislocation.MethodA consecutive group of 61 patients (seven female, 54 male) with a mean age of 34.5 years (18.9–60.1) were included in the study. All patients underwent posttraumatic clinical—Taft Score (TF), Acromioclavicular Joint Instability Score (ACJI), Constant Score (CS), Subjective Shoulder Value (SSV)—and radiological (bilateral anteroposterior stress and bilateral Alexander views) evaluation.ResultsAccording to the RW classification, the following AC dislocations were present: eight (13.1%) type I, nine (14.8%) type II, 22 (36.1%) type III, and 22 (36.1%) type V. Based on the clinical and radiographic results, a new classification is proposed: Type I instabilities show only a partial vertical displacement (≤30% coracoclavicular distance [CCD]) and type II a complete vertical displacement (>30% CCD). Both type I and II are further graded into none or partial (A) and complete DHT (B) as seen on bilateral Alexander views.ConclusionDHT can be found in low-grade instabilities and lead to inferior clinical results in the posttraumatic situation.

Shear behavior of horizontal joints between precast panels

The objective of this study is to investigate the shear resisting capacity of precast wall-to-wall horizontal connection system by dowel action and shear friction. Three types of connection systems, which have varying embedment length in the upper wall panels, were investigated. The specimens were subjected to displacement-controlled lateral loading. The parameters investigated were the load–deformation relationship, ultimate load carrying capacity, ductility and energy dissipation. The experimental values were compared with the theoretical values of ultimate shear resisting capacity calculated from the Von Mises yield criteria, ductile bending failure due to the formation of plastic hinges and the shear friction hypothesis.

A numerical modelling approach to assess the behaviour of underground cavern subjected to blast loads

The paper gives an insight into the behaviour of large underground caverns which are subjected to blast loads. Caverns are generally constructed in hard rock formation which compels us to use blasting methods for the excavation works. Comparative study was done between models with intact rock mass and discontinuities to assess the stability of cavern as a result of blast loads. Numerical modelling was performed with 3 dimensional distinct element code (3DEC) to analyse the performance of cavern walls in terms of displacement and to compute peak particle velocities (PPV) both around the cavern periphery and at surface of models. Results showed that the velocity wave with higher frequency exhibited large displacements around the periphery of cavern. Computation of PPV showed that model with horizontal joint sets showed lower PPV in comparison to model with intact rock mass. PPV values were also analysed on the surface for model consisting vertical joints spaced at 4 m intervals. Comparative study of PPV on surface vertically above the blast location between models with horizontal joints spaced at 4 m and vertical joints at 4 m intervals were conducted. Results depicted higher magnitudes of PPV for model with vertical joints in comparison to model with horizontal joints.

Seismic Response of Circular Tunnels in Jointed Rock

Although deformation along a weak joint under a strong seismic event can seriously damage the tunnel, the effect of joint has not yet been well understood or quantified. We perform a series of pseudo-static discrete element analyses to evaluate the effect of deformation along rock joint on the seismic response of circular tunnels. We also perform parallel continuum analyses to compare and quantify their differences. A comprehensive set of joint parameters are considered in this study. The results illustrate that the joint significantly increases the moment demand in the tunnel lining, whereas it has a secondary influence on the thrust. The joint stiffness and shear strength have critical influence on the tunnel response. Widely spaced joint set produces a larger tunnel response. The tunnel response is highest for vertical and horizontal joints, and the lowest when the joint dips at an angle of 45°. The moment in jointed rock may be 20 times higher than that in intact rock. The pronounced deviation from continuum analyses highlights the need to estimate the influence of discontinuities on the seismic response of underground tunnels from discrete element analyses. This may be of concern for critical structures such as nuclear facilities.

Preoperative tibial mechanical axis orientation and articular surface design influence on the coronal joint line orientation relative to the ground during gait after total knee arthroplasties.

Neutral lower limb alignment does not necessarily produce a horizontal joint line after total knee arthroplasty (TKA). The orientation of the pre- and postoperative tibial mechanical axes (TMAs-G), tibial component, and joint line relative to the ground were evaluated. The study group included 46 knees, 23 posterior-stabilized (PS) and 23 bicruciate-stabilized (BCS) TKAs. Using whole-leg standing radiographs, the static orientation of the pre- and postoperative TMAs-G and the tibial component as well as the postoperative alignment were measured. Applying image-matching techniques, the dynamic coronal orientation of the tibial component and joint line over the stance phase of gait were analysed. The correlation between static and dynamic orientation of the tibial component and differences in the joint line between the PS and BCS TKAs were evaluated. In standing, the postoperative TMA-G (0.8° ± 2.8°) and tibial component (1.5° ± 2.4°) were laterally tilted with a strong correlation. The preoperative lateral tilt of the TMA-G (7.9° ± 5.1°) was a significant predictor of the postoperative TMA-G. The lateral tilt of the tibial component increased to 5.1° ± 2.4° on dynamic analysis, and was moderately correlated to static orientation. The dynamic orientation of the joint line was smaller for the BCS (1.8° ± 2.4°) compared to the PS (5.5° ± 2.7°) TKA. Even with a mechanically well-aligned TKA, a lateral tilt of the tibial component was identified due to the lateral tilt of the postoperative TMA-G and the stance phase of gait. The BCS can better accommodate the residual lateral tilt of the joint line due to the 3° medial inclination of the joint surfaces of the implant. This study increases the awareness of surgeons regarding the possibility of the coronal joint line orientation to influence preoperative TMA-G and be accommodated by articular surface design, even in mechanically aligned TKA. IV.

Experimental study on joint stiffness with vision-based system and geometric imperfections of temporary member structure

In this paper, tests of plug-pin joints are conducted in order to obtain their mechanical parameters, including semi-rigid property. To solve the difficulties of multi-point displacement measurements for small joints, this investigation proposes a vision-based measurement system based on the principle of binocular stereo vision to improve measurement accuracy. Accurate sub-pixel location is achieved according to a template-matching algorithm based on grayscale. Joint performance, including horizontal bar joint tension and compression, semi-rigidity between horizontal bars and upright rods and bracing tension and compression, is investigated in order to acquire joint failure modes as well as load and displacement (or moment and rotation angle) curves. Through data fitting, multi-linear simplified models are proposed to illustrate the joints’ mechanical performance. This paper also investigates geometric imperfection of temporary member structure with plug-pin joints based on several substructure models and temporary grandstand units using a total station theodolite. The probabilistic models of initial member out-of-straightness and story frame out-of-plumb have been acquired, which can be used into Monte Carlo simulation to create stochastic model of the temporary member structure.

Nonlinear dynamic analysis of arch dams considering contraction joints

Arch dams are massive plain concrete structure, their stability and security are usually controlled by the tensile behavior and cracking of concrete. They are constructed as vertical monolithic cantilever elements separated by contraction joints filled with mortar. This contribution consists of the evaluation of the performance and the reliability of nonlinear joints numerical models used in the finite element open source code “Code-Aster.” These contraction joints can only transfer limited tensile stresses between the adjacent cantilever monoliths. Relative motions of the cantilever monoliths during an earthquake induce the opening, closing, and sliding of the contraction joints, resulting in significant dissipation of the seismic input energy. For these reasons, Nonlinear Time History Analysis is carried out in order to locate and estimate the probable damages of the structure in the form of joints opening. The numerical results obtained from nonlinear time history analysis show that the contraction joints opening releases the tensile stresses in the arch, but increases the compressive stresses in the arch and the vertical stresses in the cantilevers. The increase in the compressive stresses in the arch can lead to the crushing of the concrete, and to the increase of vertical stresses in the cantilevers which can exceed the tensile strength of the concrete arch, resulting in the apparition of tensile cracks along the horizontal joints. High tensile stresses may also appear along the Dam–Rock interface causing cracks along the contact surface.

MATHEMATICAL MODEL OF DPKR-2 DYZEL TRAIN CAR

Purpose. In order to study the dynamic phenomena arising when rolling stock moves along a rail track both in the straight and curved track sections, the article is aimed to construct a mathematical model of DPKr-2 diesel train car. It will be constructed on the basis of mechanical model of this car of Kryukiv Railway Car Building Works. Methodology. To construct a mathematical model a system of 38 differential equations of the diesel train movement is formed. When it is used a pneumatic spring in the core stage of spring suspension, its equivalent mechanical mo-del is presented as Kelvin-Voigt knot. It includes a parallel elastic element and an element of viscous friction. Rail track flexibility is taken into account by elastic and dissipative elements. During simulation it was assumed that the wheel pair and the track weight interacting with it were moving intact. Geometric inequalities of the left and right rails were accepted as disturbances when studying the forced vertical and horizontal oscillations. Findings. On the basis of the adopted mechanical model of the diesel train car we constructed the mathematical model consisting of 38 differential equations of motion . Originality. For the first time, for the DPKr-2 diesel train car we developed its spatial mathematical model taking into account the features of the interaction of individual elements of its construction and the possibilities of the rail track depression. When constructing the mathematical model, it was proposed to take into account the flexibility of the rail track by elastic and dissipative elements. Originality. The mathematical model of the diesel train car will be used for studying the dynamic phenomena and determining the dynamic loads of structural elements during operation. The study of these phenomena is necessary for optimal choice of the scheme and parameters of rolling stock equipment, in particular antivibration devices (spring suspension, horizontal, longitudinal and transverse joints of wheel pairs with the bogie frame, bogie with the body), as well as for reduction of dynamic forces acting on the elements of rolling stock construction and rail track.

Optimal dynamic promotion strategies in the multiple competing supply chains

ABSTRACTIn this paper, the optimal decision problem is investigated for a class of dynamic promotions in the multiple competing supply chains. Here, the dynamic advertising model is allowed to be influenced by horizontal joint promotions (HJP) and vertical joint promotions (VJP). We extend the classical Nerlove–Arrow model by considering the effect of competitive manufacturer's VJP effort on brand goodwill. Also, the continuous-time demand is constructed with the effect of competitive retailer's VJP and HJP efforts. Based on the Hamilton–Jacobi–Bellman equation, the optimal HJP and VJP strategies of supply chain members and the optimal promotion cost sharing rate of each manufacturer are obtained under the Decentralized–Decentralized and Decentralized–Centralized structures, respectively. Subsequently, the comparison between the two structures shows that the optimal VJP and HJP efforts of supply chain members increase with their marginal profits and each manufacturer is willing to pay for the retailer's VJP effort level when the marginal profit of manufacturer exceeds the half of retailer's marginal profit. Numerical examples are provided to show the change of profit difference with parameters α and β under the different structures.