Lateral In-plane Research Articles

Lateral performance of cold‐formed steel OSB‐sheathed stud wall panels

AbstractOriented Strand Boards (OSB) are currently one the most widely used cladding options in cold‐formed steel (CFS) stud wall panels. The sheathing generates significant resistance to lateral loads owing to its diaphragm stiffness, which is however typically not fully exploited in design. This paper aims to investigate the lateral inplane behaviour of CFS OSB‐sheathed stud wall panels and provide insight into their failure mechanisms and seismic characteristics. Detailed finite element (FE) models of CFS OSB‐sheathed wall panels were developed, featuring material nonlinearity, detailed connection behaviour and geometric imperfections, and their accuracy was validated against previously conducted experiments. The validated FE models were then employed in a parametric study to investigate the effects of key design variables, including the OSB and CFS element thicknesses and the board configuration, on the structural performance parameters and seismic characteristics of the walls. The results demonstrate that using thinner OSB sheathing resulted in lower lateral strength, initial stiffness and energy dissipation, but increased the ductility and ultimate displacement by up to 40%. It was also shown that the presence of horizontal/vertical seams significantly reduces the lateral load capacity and initial stiffness.

In-plane seismic performance of an innovative steel modular reinforcement system for URM walls

An experimental and numerical research, aimed at evaluating the in-plane seismic performance of an innovative steel modular system for the reinforcement of load-bearing masonry walls (named "Resisto 5.9", designed by Progetto Sisma s.r.l.), is currently underway at the EUCENTRE Foundation in Pavia. Two different masonry typologies, representing common solutions in Italian existing buildings, were considered in this campaign: one made up with solid clay bricks and lime mortar, with "header bond" pattern, and the other with a typical Italian hollow clay "doppio UNI" unit and cement-lime mortar, assembled in a "Flemish bond" pattern. The experimental tests included first the complete mechanical characterization of units, mortars, masonry typologies and of the strengthening system components (i.e. steel elements and anchors). In-plane quasi-static tests were performed on different batches of full--scale specimens to investigate the influence of the proposed reinforcement system on the lateral in-plane response of the walls, compared to their unreinforced conditions. The cyclic behaviour of the masonry piers was analysed in terms of elastic stiffness, lateral strength, displacement capacity and energy dissipation, depending on the achieved damage mechanism. The numerical study of the ongoing campaign consisted of a series of parametric analyses on advanced discontinuous models based on the Distinct Element Method (DEM), considering different wall dimensions, vertical load levels and boundary conditions, in addition to those tested experimentally. Moreover, the numerical campaign was extended also to other possible masonry typologies, varying the bond pattern and the mechanical properties with respect to the experimentally tested solutions. In this paper, the results of the experimental tests on solid brick masonry together with a preliminary overview of the findings of the numerical study, still ongoing, were reported.

Topologically-protected interior for three-dimensional confluent cellular collectives

Organoids are in vitro cellular collectives from which, for example, brain-like, or gut-like, or kidney-like structures emerge. To make quantitative predictions regarding the morphology and rheology of a cellular collective in its initial stages of development, we construct and study a three-dimensional vertex model. In such a model, the cells are represented as deformable polyhedrons with cells sharing faces such that there are no gaps between them, otherwise known as confluent. In a bulk model with periodic boundary conditions, we find a rigidity transition as a function of the target cell shape index ${s}_{0}$ with a critical value ${s}_{0}^{*}=5.39\ifmmode\pm\else\textpm\fi{}0.01$. For a confluent cellular collective with a finite boundary, and in the presence of lateral extensile and in-plane, radial extensile deformations, we find a significant boundary-bulk effect that is one-cell layer thick. More specifically, for lateral extensile deformations, the cells in the bulk are much less aligned with the direction of the lateral deformation than the cells at the boundary. For in-plane, radial deformations, the cells in the bulk exhibit much less reorientation perpendicular to the radial direction than the cells at the boundary. In other words, for both deformations, the bulk, interior cells are topologically protected from the deformations, at least over time scales much slower than the timescale for cellular rearrangements and up to reasonable amounts of strain. Our results provide an underlying mechanism for some observed cell shape patterning in organoids and in in vivo settings. Finally, we discuss the use of a cellular-based approach to designing organoids with new types of morphologies to study the intricate relationship between structure and function at the multicellular scale.

Empirical formulations for estimation of the ultimate strength of the perforated stiffened panels under the combined lateral pressure and in-plane compression

The holes artificially cut for a certain purpose can greatly reduce the ultimate strength of the perforated stiffened panels. In this paper, the ABAQUS finite element analysis program is used to investigate the effect of the position and size of the circular holes, the slenderness ratio, the aspect ratio, and the loading ratio on the ultimate strength of the perforated stiffened panels. Periodic and symmetric boundary conditions are applied to the (1/2 + 1+1/2) span model to consider the continuity of the stiffened panel in modeling. The results show that the ultimate strength of the perforated stiffened panel is highly dependent on the location and size of the hole. An empirical formula to primarily predict the ultimate strength reduction rate of perforated stiffened panel is proposed, and its accuracy is evaluated.

STRENGTH OF SHIPS’ GRILLAGES UNDER LATERAL LOAD AND IN-PLANE COMPRESSION

The paper deals with strength of a grillage loaded by lateral load and in-plane compression load (in one direction). It consists of a system of prismatic girders crossing under 90°. The compression load is taken by the longitudinal girders that are elastically fixed on rigid supports. The system of aggregated differential equations is derived for solution of the problem using the Lagrange method. It allows for replacement of the system of aggregated differential equations by a system of independent differential equations. These equations for the case of simultaneous action of lateral and longitudinal compression load have the form of differential equations for bending of prismatic girders laying on elastic foundation and loaded with lateral and longitudinal compression forces. When only lateral load exists, the form of these equations coincides with the form of differential equations for bending of girders laying on elastic foundation and loaded with lateral load alone. When only longitudinal compression load exists, the form of these equations coincides with the form of differential equations for buckling of girders laying on elastic foundation.
 Solutions are given for bending of a grillage (the first two problems). Formulas are derived for calculation of the parameters of longitudinal girders’ bending when girders’ end sections are elastically fixed. Also, formulas are derived for calculation of the reaction forces at cross-points of transverse and longitudinal girders. When only longitudinal compression load exists (third problem), a solution is given for the connection between the coefficient of elastic foundation’s rigidity and the Euler force. Results obtained by using the proposed method are compared with FEA simulations.

Compression and In-plane Seismic Behaviour of Ashlar Three-leaf Stone Masonry Walls

ABSTRACT There is a lack of knowledge regarding the parameters needed for the effective seismic performance assessment of historical stone masonry buildings. The paper presents the results of an extensive experimental campaign consisting of four compression and fifteen in-plane cyclic shear tests on three-leaf ashlar stone masonry walls and its constituents. The morphology, level of vertical load, and testing boundary conditions were systematically varied, and their influence on the load-bearing and deformation capacities, stiffness, ductility and energy dissipation was analysed. Good consolidation of the inner core enables in-plane failure mechanism of the walls to occur without decisive out-of-plane damage. The boundary conditions applied significantly influence the failure modes and large deformation capacities obtained, whereas transverse connections in the case of a shear failure mechanism do not significantly influence the overall lateral in-plane response of walls.

Edge Race-Tracking during Film-Sealed Compression Resin Transfer Molding

Edge race-tracking is a frequently reported issue during resin transfer molding. It is caused by highly permeable channels and areas between the preform edge and cavity, which can significantly change the preform impregnation pattern. To date, information is scarce on the effect of edge race-tracking in compression resin transfer molding (CRTM). To close this gap, laboratory equipment was developed to study the CRTM preform impregnation via flow visualization experiments. The preform was thereby encapsulated in thin thermoplastic films sealing its impregnation. Film-sealed compression resin transfer molding (FS-CRTM) experiments of preforms with a small geometrical aspect ratio showed fast filling of the injection gap and a subsequent through-thickness preform impregnation. Creating an edge race-tracking channel, an additional lateral in-plane flow from the channel towards the preform center was observed, initiating soon after the injection started and caused by the spatial connection between the injection gap and the race-tracking channel. To diminish edge race-tracking, a passive flow control strategy was implemented via a split design of the upper tool to spatially isolate the injection gap from the channel and to pre-compact the preform edge. A delayed and reduced lateral race-tracking flow was observed, showing that the passive flow control strategy increases the process robustness of FS-CRTM regarding edge race-tracking effects.

US-Guided Transforaminal Cervical Nerve Root Block: A Novel Lateral in-Plane Approach.

The aim of the present study was to investigate the effectiveness and safety of a novel lateral in-plane approach for ultrasound-guided transforaminal cervical nerve root block (US-guided TF-CNRB) in the treatment of cervical radiculopathic pain. The design of the present study consisted of an institutional, retrospective case series. The present study was conducted at a university hospital. Thirty-two patients with cervical radiculopathy who were resistant to conservative therapies and regular US-guided CNRB were included as participants. The included patients were treated with US-guided TF-CNRB. During the treatments, using real-time fluoroscopy, we monitored the spreading patterns of a contrast medium and double confirmed the positions of needle tips. Pain numeric rating scales (NRS) and symptom relief grades were determined via telephone interviews at one, four, and 12 weeks after the procedures. US-guided TF-CNRB was performed at the C5 level in six patients, the C6 level in 18 patients, and the C7 level in eight patients. Compared with NRS at baseline, pain scores decreased throughout the observation period. Symptom relief rates of US-guided TF-CNRB at one, four, and 12 weeks were 72%, 69%, and 63%, respectively. Venous blood was aspirated during the procedures in two patients, and the needle tips were corrected. No intravascular injections or neurologic injuries were observed. US-guided TF-CNRB produced circumferential spreading around the involved cervical nerve root and showed significant clinical effectiveness in patients resistant to regular US-guided CNRB.

Vibration characteristics of zigzag FGM single-walled carbon nanotubes based on Ritz method with ring-stiffeners

In this study, Rayleigh–Ritz method is used for free vibrations of functionally graded carbon nanotubes based on Sander’s shell theory. The effects of various parameters for length-to-diameter ratio and height-to-diameter ratio for zigzag single-walled carbon nanotubes have been fully inspected. The frequency pattern with mass density per unit lateral area and in-plane rigidity has been calculated and found reverse order. The tube material is taken as functionally graded material and their material quantity is located by the polynomial volume fraction law. It is examined that the frequencies increase on increasing the ratio of height-to-diameter. Moreover, the impact of ring supports around the tube circumferential is studied for their various positions along tube axial length. These rings are restrained the radial displacement in the transverse direction.

Lateral in-plane seismic response of confined masonry walls: From numerical to backbone models

Confined masonry (CM) is a widely used solution for buildings in developing countries and has potential for worldwide application when considering its economic and constructive advantages. Although a large background of experimental testing of CM walls is available, numerical studies are further needed to extend the existing knowledge and derive analytical rules to adopt in design codes. In this work, a parametric numerical study is performed, aimed to characterize the lateral in-plane response of CM walls under different variables and to establish a dataset for comparison of engineering demand parameters, towards the proposal of predictive models. Benchmark walls tested under lateral in-plane loading are used to calibrate a finite element modelling approach for pushover analysis. Based on the results of the parametric study, a formulation and charts are proposed to respectively estimate the lateral resistance and displacement capacity of CM walls with features similar to the ones used as benchmark.

Mass density effect on vibration of zigzag and chiral SWCNTs: A theoretical study

Carbon nanotubes fascinate new materials with astonishing mechanical, optical, and electrical properties. In fact, carbon nanotubes are kinds of rolled graphene sheets, and the rolling manner shows the basic properties of the tube, and that is actually the main reason for the extraordinary feature of the carbon nanotubes. This paper aims to presents formulation of Love’s shell theory for single-wall carbon nanotubes (SWCNTs) using Galerkin’s method. For this system, the governing equation is developed with proposed method. It is assumed that C–C and C–F support conditions are applied on the edge of carbon nanotube. Zigzag and chiral structures are considered for the vibrational analysis to investigate the effect of different mode and in-plane rigidity with end conditions. Moreover, the influence of mass density per unit lateral area on the same structure is also developed. It is also concluded that the fundamental frequencies of chiral tubes are lower than that of zigzag tubes frequencies. By increasing values of in-plane rigidity, resulting frequencies also increase and frequencies decrease on increasing mass density per unit lateral area. Though the trends of frequency values of both mass density per unit lateral area and in-plane rigidity are converse to each other. It is shown that variation in mass density has a significant effect on the vibration of SWCNTs. To generate the fundamental natural frequencies and for better accuracy and effectiveness, the computer software MATLAB is used. Tube dynamical equations for the present problem are taken in the integral form energy expressions for a carbon nanotube. The axial modal deformations are approximated by making use of the beam functions. The proposed model is continuum-model for getting the dynamic character of SWCNTs and to validate the results by earlier methods.

A New Procedure for Determination of Lateral In-plane Failure Modes of Reinforced Concrete Squat Shear Walls

Reinforced concrete squat shear walls (RCSSWs) are structural elements commonly used in low-rise buildings and as bridge pier-walls and building basement walls. RCSSWs lateral in-plane failure modes are diagonal tension, diagonal compression, and sliding shear, where all are shear dominant. Determination of these failure modes is especially required for seismic design and evaluation of RCSSWs. A new procedure for such determination is introduced based on modeling the wall as a two-dimensional cracked reinforced concrete element modeled using the disturbed stress field model. This procedure considers the stress states of concrete and main rebars according to the shear dominant lateral nature of each failure mode of RCSSWs. The main stress-related behavioral indicators and their selected thresholds are presented. The accuracy and robustness of the proposed failure mode determination procedure is tested against 12 experimental cyclic test results. High accuracy and robustness are observed for determining different lateral in-plane failure modes of RCSSWs.

Effects of vertical stresses and flanges on seismic behavior of unreinforced brick masonry

Lateral in-plane response plays crucial role in seismic behavior of masonry structures. The aim of this article is to experimentally investigate the effects of vertical stresses and flanges (transverse walls) on the lateral in-plane response of the unreinforced brick masonry (URBM) walls. The experimental work included lateral in-plane quasi-static cyclic tests on full-scale walls (both with & without flanges). The vertical stresses resulting from typical single and two story unreinforced masonry buildings were simulated on full scale URBM walls. Flanges were introduced at both ends of the in-plane wall in single direction. In essence, the lateral in-plane stiffness & strength, deformability and energy dissipation of the two classes of walls are compared and the differences are quantified to help understand the effects of flanges on the in-plane response of masonry walls. The resulting damage mechanism and failure modes for each case are critically analyzed. The experimental results indicate that both vertical stresses and flanges incorporation significantly improved seismic response of URBM walls. In addition, the participation of flanges is critical in both vertical stress conditions.

Application of the idealized structural unit method for ultimate strength analyses of stiffened plate structures

ABSTRACTTo assess the safety of ship structures, the determination of the ultimate hull girder strength is of essential importance. The idealized structural unit method (ISUM) is a simplified method to perform progressive collapse analyses of large structural systems with less computational efforts compared to non-linear finite element analyses (FEA). In this paper, the basic concept and the applicability of ISUM are demonstrated for a stiffened plate panel under lateral pressure and inplane thrust. Ship structures are subjected to global bending moments and lateral pressure loads. To simulate the collapse behaviour of such complex structural systems, a box-girder specimen in bending is investigated. Appropriate numerical models are presented and the corresponding ultimate strength values are validated against experimental results. To simulate combined load cases with lateral pressure loads acting on the bottom of the box-girder specimen, the corresponding ultimate strength values determined with ISUM are compared with non-linear FEA results.

Enhancement of lateral in-plane capacity of partially grouted concrete masonry shear walls

The goal of the research presented herein is to investigate a new approach to the reinforcement of partially grouted walls, double side-by-side reinforced cells, in order to enhance the seismic performance of such walls. Specifically, the results from the destructive tests of three cantilever full-scale square masonry shear walls are presented. The control wall was constructed using the conventional single cell reinforcement (SR) approach, with the remaining two walls constructed using double cell reinforcement with bond beams (DR), and with the addition of bed-joint reinforcement (DR-JR), respectively. To permit direct comparison, the total amount of reinforcement in the SR and DR walls was held constant. The experimental investigation indicated that the DR reinforcement approach resulted in significantly improved lateral in-plane response compared to the conventional SR approach. Specifically, the DR wall exhibited a 34% increase in shear capacity and 47% increase in displacement ductility. To investigate the effect of grouting on the response of proposed reinforcement details a numerical modeling technique was developed based on the infilled-frame concept and calibrated with the experimental behavior of considered walls. It is evident from the results of numerical modeling that response of walls is in a good agreement with the behavior observed in the experiments. Numerical model showed that the behavior of grouted and ungrouted parts of PG walls are similar to a frame and an infilled, respectively. Grouting double side-by-side cells enhances the frame action of grouted masonry parts and also provides a better confinement for the infilled masonry. As a result of the strengthened frame the performance of wall DR was improved significantly compared to wall SR.

Seismic damage detection for a steel braced frame structure

A new approach for global detection of seismic damage in a single-storey steel concentrically braced frame (CBF) structure is presented. The filtered lateral in-plane acceleration response of the CBF structure is integrated twice to provide the lateral in-plane displacement that is used to infer buckling and yielding damage. The level of interstorey drift of the CBF during a seismic excitation allows the yield and buckling of the bracing members to be identified and indirectly detects damage based on exceedance of calculated lateral in-plane displacement limits. A band-pass filter removes noise from the acceleration signal followed by baseline correction being used to reduce the drift in velocity and displacement during numerical integration. This pre-processing results in reliable numerical integration of the frame acceleration that predicts the displacement response accurately when compared to the measured lateral displacement of the CBF structure. Importantly, the structural damage is not assumed through removal of bracing members, rather damage is induced through actual seismic loading. The buckling and yielding displacement threshold limits used to identify damage are demonstrated to identify accurately the initiation of buckling and yielding.

Strength of Ships’ Grillages Under Lateral Load and In-Plane Compression

The paper deals with strength of a grillage loaded by lateral load and in-plane compression load (in one direction). It consists of a system of prismatic girders crossing under 90°. The compression load is taken by the longitudinal girders that are elastically fixed on rigid supports. The system of aggregated differential equations is derived for solution of the problem using the Lagrange method. It allows for replacement of the system of aggregated differential equations by a system of independent differential equations. These equations for the case of simultaneous action of lateral and longitudinal compression load have the form of differential equations for bending of prismatic girders laying on elastic foundation and loaded with lateral and longitudinal compression forces. When only lateral load exists, the form of these equations coincides with the form of differential equations for bending of girders laying on elastic foundation and loaded with lateral load alone. When only longitudinal compression load exists, the form of these equations coincides with the form of differential equations for buckling of girders laying on elastic foundation. Solutions are given for bending of a grillage (the first two problems). Formulas are derived for calculation of the parameters of longitudinal girders’ bending when girders’ end sections are elastically fixed. Also, formulas are derived for calculation of the reaction forces at cross-points of transverse and longitudinal girders. When only longitudinal compression load exists (third problem), a solution is given for the connection between the coefficient of elastic foundation’s rigidity and the Euler force. Results obtained by using the proposed method are compared with FEA simulations.

Comparison of Spinal Cord Motion Versus Vertebral Body Motion During Magnetic Resonance Imaging–Guided Radiation Therapy (MR-IGRT)

An a priori assumption of all currently available IGRT methods is that vertebral (VB) body position is an accurate surrogate for spinal cord (SC) position, since the spinal cord is not well visualized by x-ray based imaging (kV:kV, CBCT). A new MR-IGRT system has been developed which consists of a split 0.35T MR scanner straddled by three 60Co heads mounted on a ring gantry which share a common isocenter. Given the superior ability for MR to visualize the SC, we sought to use MR-IGRT to compare the relative motion of the SC versus the VB. Three healthy volunteers were immobilized in vacuum immobilization bags and underwent volumetric MR at baseline (t0) and again in 5 minute intervals during the course of a mock treatment on a MR-IGRT system. The mock treatment was repeated for 2 additional fractions by removing the patient from the immobilization and then restarting the process completely. The MR protocol was a true fast imaging with steady state precession T2*/T1-weighted volumetric scan with a 1.5 x 1.5 mm resolution and field of view selected based on patient size. Images were imported into a third party treatment planning system, and registrations were performed at the T5 VB level for each patient and each fraction with t0 as reference using either (1) the VB or (2) the SC. Registrations were performed via automated registration with a narrow field of view followed by manual adjustment by the clinician. Differences in motion in the lateral and anterior-posterior (AP) directions and 2D in-plane shifts between SV and VB were calculated. All 3 volunteers were able to complete the course of mock treatment. The SC was well visualized with a high level of contrast between SC and surrounding CSF. Average difference in lateral motion of SC relative to VB across all 3 fractions for patients 1, 2, and 3 was -0.7 +/- 0.4 mm, -0.8 +/- 0.5 mm, and -0.4 +/- 0.3 mm. Average difference in AP motion was -0.1 +/- 0.6 mm, -0.1 +/- 0.5 mm, and 0.2 +/- 0.3 mm. Average difference in 2D motion was 0.9 +/- 0.4 mm, 0.9 +/- 0.5 mm, 0.6 +/- 0.3 mm. No time trends were noted across the 30 minute treatment. Maximum lateral, AP, and VS between SC and VB across all patients and all fractions was -1.4 mm, -1.2 mm, and 1.8 mm, respectively. The SC is well visualized with MR-IGRT and for the first time patient specific shifts can be made directly based on SC position rather than VB as a surrogate. A small but consistent difference in calculated shifts was observed when shifting based on SC versus VB, largely in the lateral direction. Average differences in a clinically relevant 2D shift were generally < 1 mm, but were up to 1.8 mm at certain time points. Confirmed in a larger cohort, such data may also be informative for generation of SC planning risk volume margins at a population level.

Controlled nucleation of topological defects in the stripe domain patterns of lateral multilayers with perpendicular magnetic anisotropy

Magnetic lateral multilayers have been fabricated on weak perpendicular magnetic anisotropy amorphous Nd-Co films in order to perform a systematic study on the conditions for controlled nucleation of topological defects within their magnetic stripe domain pattern. A lateral thickness modulation of period $w$ is defined on the nanostructured samples that, in turn, induces a lateral modulation of both magnetic stripe domain periods $\lambda$ and average in-plane magnetization component $M_{inplane}$. Depending on lateral multilayer period and in-plane applied field, thin and thick regions switch independently during in-plane magnetization reversal and domain walls are created within the in-plane magnetization configuration coupled to variable angle grain boundaries and disclinations within the magnetic stripe domain patterns. This process is mainly driven by the competition between rotatable anisotropy (that couples the magnetic stripe pattern to in-plane magnetization) and in-plane shape anisotropy induced by the periodic thickness modulation. However, as the structural period $w$ becomes comparable to magnetic stripe period $\lambda$, the nucleation of topological defects at the interfaces between thin and thick regions is hindered by a size effect and stripe domains in the different thickness regions become strongly coupled.

Percutaneous Ultrasound-guided Central Venous Catheters: The Lateral In-plane Technique for Internal Jugular Vein Access

To describe the possible ultrasound guidance techniques for the insertion of central venous catheters (CVCs), with emphasis particularly to the lateral short axis in-plane technique. Numerous articles have shown significant benefits of using ultrasound guidance for venous access. Two main approaches to vein puncture are available, when considering visualization of the needle during its entry into the vein under the ultrasound beam: in-plane and out-of-plane, which can be combined with two types of vein visualization, placing the ultrasound probe on the vein long axis or short axis. Advantages and limitations in internal jugular vein (IJV) cannulation for long-term dialysis CVCs are described for the above-mentioned approaches and visualizations. The lateral short axis in-plane technique has virtually no limitations, ensuring most benefits. The lateral short axis in-plane technique should be considered the first-line technique for IJV cannulation.