Lateral Reinforcement Research Articles

The Seismic Behavior of Rectangular Concrete-Encased Steel Bridge Piers: A Review

This paper proposes a review of the previous research work and the representative publications regarding the seismic behavior of the concrete-encased steel (CES) columns. Concrete-encased steel sections are composed of steel sections encased in reinforced concrete members. The research work recently showed increased attention to this type of column due to its advantages compared to conventional reinforced concrete columns. Firstly, the analytical studies of the behavior of the CES columns under axial loads, including comparative studies between different research works, are presented. Then, the behavior of the CES columns under combined axial and flexural loads is also highlighted. An overview of the analytical confinement material models is addressed. In addition, the discussion and summary of the seismic behavior of the CES columns and the important parameters affecting the seismic behavior of these types of columns are included. Although important progress has been made by the previous studies in the CES columns under the axial load and the combination of axial and seismic loads, they fundamentally focused on the building columns, and little attention was paid to the impact of lateral reinforcement and their configuration in bridge piers. Due to the lack of studies on the parameters affecting the seismic behavior of the bridges, more studies should still be made to better understand the behavior of the CES bridge piers. This paper provides a reference for the research and engineering practice of concrete-encased steel bridge piers. It also concludes with suggestions for future studies to integrate the seismic requirement of the CES bridge piers in Canada.

Structural Performance of Ferrocement Hollow Shear Walls Subjected to Lateral and Compressive Axial Loads

In this study, ten shear walls were experimentally tested to examine behaviour of ferrocement hollow shear walls subjected to axial and lateral loads. Ferrocement mortar (FM) was used to build eight walls, while normal concrete (NC) was used to build two controls. Walls were lateral reinforced using conventional stirrups, two layers of welded wire mesh (WWM), and expanded steel mesh (ESM). Two specimens lacked lateral reinforcement except for one transverse web in the center of the inner hole. Two symmetric groups of five walls each were created by dividing the walls. While the other group was loaded laterally, one group was loaded axially. In each group, the load–displacement relationship, maximum load and associated displacement, stiffness, ductility, and failure mechanism of FM and NC walls were compared. The results showed that FM walls provided with ESM and WWM had ultimate axial loads that were, respectively, 36% and 19% higher than NC control walls. Ultimate lateral loads and related ultimate drifts of FM walls reinforced with two layers of WWM and ESM were, respectively, 68% and 39%, 96% and 43.5%, larger than control NC wall. For lateral loads greater than those applied to the NC control wall, stiffness increase ratios for FM walls ranged from 2.5% to 89.5%, and for axial loads, they ranged from 20% to 150.5%. The ductility of FM walls increased when compared to NC walls by 58.5% and 158.8% for axial and lateral loading, respectively, when two layers of WWM were utilized to lateral reinforce FM walls. When two layers of ESM were applied to laterally reinforce FM walls in comparison to an NC wall, this increased the walls' ductility under axial and lateral loads by 110.5% and 214.7%, respectively.

Experimental and numerical study on extended endplate beam-column joints after high temperature to resist progressive collapse

This paper presents experimental and numerical investigations on the collapse-resisting behavior of extended endplate beam-column joints after high temperatures. The failure patterns and structural responses of extended endplate (EP) joints after high temperature to resist progressive collapse were first described, and then the effects of fire temperature and temperature duration on their collapse resistance mechanisms were also analyzed in detail. The test results demonstrate that all specimens withdrew from work owing to the serious deformation of endplate bolt holes or the brittle fracture of high-strength bolts, resulting in the catenary mechanisms of EP joints not being adequately developed. Compared with previous studies, it is shown that the fire temperature exerts the most significant effects on the carrying capacities and deformability of EP joints, and the collapse resistance of corresponding assemblies is most sensitive to the fire temperature. However, the temperature durations have an insignificant influence on the development of flexural mechanism resistance, especially for those after 600 °C and 800 °C. Moreover, the corresponding refined FE models in consideration of the damage and fracture of ductile metals have been established to reproduce the structural response of specimens after high temperature. To improve the post-fire collapse-resisting performance of assemblies, both the lateral plate reinforcement and welding reinforcement methods were proposed and compared with the assistance of validated FE models. From a practical viewpoint, the reinforcement with lateral plates is determined as a superior technique for post-fire EP joints against progressive collapse.

Calculation of Characteristic Point Parameters for Restoring Model of Corroded Short-Pier RC Shear Walls

Based on the quasi-static tests of 12 corroded RC (reinforced concrete) shear walls, it was found that reinforcement corrosion has a great influence on the skeleton curve of RC shear walls. With an increase in the degree of corrosion, the bearing capacity of specimens decreases, and the deformation capacity worsens. Increasing the diameter of longitudinal reinforcements can significantly improve the bearing capacity of corroded RC shear walls, while the deformation capacity of corroded specimens can be improved by increasing the lateral distributed reinforcement or the transverse reinforcement in the embedded column. In order to accurately evaluate the seismic performance of corroded RC shear walls, we considered descent segments of four broken-line models to estimate the skeleton curve. After considering the influence of corrosion on the parameters of the characteristic point for the skeleton curve, the calculation formulas of the characteristic point parameters of the skeleton curve for the corroded RC shear wall were determined based on the test data fitting. It was proven that the formula for the characteristic point parameters for the skeleton curve of corroded RC shear walls has good applicability. This study lays a theoretical foundation for the seismic performance evaluation of an RC shear wall structure in a salt fog environment. It provides a theoretical basis for further improving the life-cycle seismic capacity evaluation system for RC structures.

Experimental investigation of the seismic behaviour of eccentric RC beams with different reinforcement configurations

In reinforced concrete (RC) buildings, the seismic behaviour of RC beams with flush outside faces of beams and columns has not been verified by experiments. In this study, four large RC beam specimens were fabricated and an experimental verification was conducted. The results showed that all of the specimens (including three beam specimens with flush outside faces of beams and columns) could withstand ultimate drift angles up to 4% rad. In addition, the lateral strength and seismic behaviour of a specimen with a concrete cover of 85 mm were no less than those of the benchmark specimen, so a concrete cover thickness of 85–40 mm should be acceptable for RC beams. The seismic behaviour of two specimens with lateral U-shaped auxiliary transverse reinforcement and a concrete cover of 85 mm was better than that of the benchmark specimen, but the crack width of the latter was wider and the spalling degree of the concrete cover was more serious. Based on the results of this work, the practical recommendation is to adopt lateral U-shaped auxiliary transverse reinforcement in which the two legs extend beyond half the width of the hoop, with two auxiliary longitudinal reinforcements and the same spacing as the hoop.

Additional cartilage reinforcement of the annulus in myringoplasty for subtotal perforation

ObjectiveIn this study, graft success, hearing outcome, and complications were compared following the repair of subtotal perforation using a cartilage reinforcement underlay technique (CRUT) versus the traditional cartilage underlay technique (TCUT). Study designRandomized controlled trial. Materials and methodsSeventy-six patients with subtotal perforations were prospectively randomized to the CRUT (n = 38) or TCUT (n = 38) group. The graft success rate, hearing outcome, and complications were compared at 12 months. ResultsThe mean operation time was 32.9 ± 4.2 (range: 26–47) min in the CRUT group and 51.8 ± 6.3 (range: 48–73) min in the TCUT group (P < 0.001). At 12 months postoperatively, no residual perforation was seen in either group. The graft success rate was 94.7 % (36/38) in the CRUT group and 92.1 % (35/38) in the TCUT group; the difference was not significant (P = 0.643). The postoperative air bone gap (ABG) was significantly improved compared to the preoperative value in both groups, without significant between-group differences in either the preoperative (P = 0.741) or postoperative (P = 0.865) ABG or the mean ABG gain (P = 0.812). Additionally, there were no significant between-group differences in the preoperative (P = 0.887) or postoperative (P = 0.753) mean bone-conduction pure tone average. In the TCUT group, seven (18.4 %) patients developed temporary hypogeusia and two (5.3 %) had external auditory canal scarring. Graft cholesteatoma was not observed in either group. ConclusionIn the treatment of subtotal perforations, lateral reinforcement of the annulus with additional cartilage is simpler than traditional cartilage underlay for achieving graft and hearing success. The technique also does not involve raising the tympanomeatal flap or removing perforation margins.

Knee Flexion Angle of Fixation During Anterolateral Ligament Reconstruction or Lateral Extra-articular Tenodesis: A Systematic Review and Meta-analysis of Lateral Extra-articular Reinforcement Techniques Performed in Conjunction With ACL Reconstruction.

Anterolateral ligament reconstruction (ALLR) or lateral extra-articular tenodesis (LET) is being used more frequently in conjunction with anterior cruciate ligament reconstruction (ACLR). However, the knee flexion angle at which fixation of ALLR or LET is performed during the procedure is quite variable based on existing technique descriptions. The purpose of this study was to identify whether flexion angle at the time of ALLR/LET fixation affected postoperative outcomes in a clinical population. It was hypothesized that ALLR/LET fixation at low versus high flexion angles would lead to no statistically significant differences in patient-reported outcome measures and graft failure rates. Systematic review; Level of evidence, 4. The PubMed, Embase, and Cochrane Library databases were searched according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines to identify published clinical studies of ACLR with ALLR/LET in which the knee flexion angle at the time of ALLR/LET was reported. A priori, low flexion was defined as 0° to 30°, and high flexion was defined as 60° to 90°. Studies were excluded if the flexion angle was between 31° and 59° because these angles constituted neither low nor high flexion angles and including them in an analysis of high versus low flexion angle at fixation would have biased the study results toward the null. The overall risk of bias was assessed using the Newcastle-Ottawa Scale. The pooled results of the studies were analyzed using the International Knee Documentation Committee (IKDC), Lysholm, and Tegner scores, along with reported graft failure rates. A total of 32 clinical studies (5230 patients) met inclusion criteria: 22 studies (1999 patients) in the low-flexion group and 10 studies (3231 patients) in the high-flexion group. The median Newcastle-Ottawa Scale score was 6. Comparisons of patients with a low flexion angle versus a high flexion angle demonstrated no differences in the IKDC (P = .84), Lysholm (P = .67), or Tegner (P = .44) scores or in graft failure (3.4% vs 4.1%, respectively; P = .69). The results of this review indicated that ACLR performed in conjunction with ALLR/LET provides good to excellent patient-reported outcomes and low graft failure rates when ALLR/LET fixation is performed in either low or high knee flexion.

Full-scale and half-scale fibreglass-confined concrete columns for seismic resilience

Steel corrosion is by far the biggest durability issue for many reinforced concrete bridge structures worldwide. The columns in these bridges can be critical, especially for seismic resistance. In this study, glass-fibre-reinforced-polymer bars were investigated as an alternative to steel for sustainable and resilient bridge construction. As lateral reinforcement is more susceptible to corrosion, and structures fully reinforced with fibreglass bars display softer responses with lower shear and flexural capacity, fibreglass spirals and longitudinal steel reinforcement were used in the tested columns. The experimental programme included the design, construction and seismic testing of full-scale (508 mm diameter) and half-scale (356 mm diameter) columns. The other variables investigated were the axial load and the amount and spacing of spirals. For both column sizes, fibreglass spirals provided increasing confining pressure to the concrete core with increased deformations. For the full-scale columns, no adverse size effects were observed in comparison to the half-scale columns. The columns produced large ductility and energy dissipation. Results from selected representative specimens are presented here to establish the feasibility of using fibreglass spirals in circular bridge columns. Resilience can thus be built into new columns through innovative durable fibreglass lateral reinforcement, with similar if not superior behaviour to steel-reinforced columns.

Numeričko ispitivanje učinka uvjeta oslanjanja na posmično ponašanje grede u armiranobetonskim gredama realnih veličina

In studies on beams in the literature, the beam elements are designed and tested as simply supported. Therefore, in this study, the behaviour of reinforced concrete (RC) beams under fixed support conditions was numerically investigated using ANSYS finite element software. The variables used in the study are the shear span/effective depth ratio (a/d) and stirrup spacing of the analysed specimens. In this study, 16 RC beams on a 1/1 scale were analysed in 4-point bending protocol. The a/d ratios were assumed to be 1.0, 2.0, and 3.0, in the test members produced. In addition, as another variable, the lateral reinforcement amount was designed and analysed at f8/75, f8/150 and f8/300 mm spacings without stirrups. Load-displacement and stiffness graphs are drawn based on the numerical results. The numerical results were interpreted and compared based on the graphs drawn for each analysis, stress distribution, and damage occurrence in the experiments. The results indicated that the a/d ratio and number of stirrups had strong effects on the behaviour of the fixed supported beams. The results of the beam analyses obtained using ANSYS finite element software were consistent with the experimental results.

An experimental study for effectiveness of steel fibre reinforced exterior beam-column joints under cyclic resistance

An ability of the structure to sustain levels of inelastic deformation, implicit in ductility values, is dependent on the material and detailing used. In order to achieve this high percentage of lateral reinforcement in the core of the joint is needed; which lead to reinforcement congestion and construction difficulties. In this paper, the behaviour of beam-column joint was investigated for different variations in spacing of lateral reinforcement in critical region. This increased spacing of lateral hoops reduced the reinforcement conjunction and addition of steel fibre reinforced concrete (SFRC) for same region help to remove deficiency due to removal of lateral reinforcement. The steel fibre volume fraction of 2% was used in critical region. Test results of six one-third scaled beams-column joints of reinforce concrete frame are presented to study the influence of steel fibres for effective reduction of lateral hoops in joint region. The experimental investigations also incorporate the evaluation of parameters such as ultimate strength, energy dissipation, ductility, stiffness, specific damping capacity and crack patterns. An experimental result demonstrated that SFRC beam-column joint perform satisfactorily and showed enhancement in all above properties. The behaviour of beam-column joint also showed that the additions of fibre in critical region provided necessary confinement and ductility after reduction in lateral hoops.

Calcium phosphate cement promotes the stability of osteoporotic lumbar pedicle screw by enhancer-injecters with different number of holes

BackgroundsThis study aimed to compare whether Calcium phosphate cement (CPC) promotes the stability of osteoporotic lumbar pedicle screw by enhancer-injecters with different number of holes.MethodsThrough a self-designed bone cement injection device, the pedicle screw canal was strengthened with calcium phosphate bone cement, and divided into 4-hole group, 6-hole group, 8-hole group, straight pore group and the control group. The screw was inserted into the mechanical test module, the Maximum insertion torque and Maximum axial pull-out strength were recorded, and the distribution of calcium phosphate bone cement was analyzed by CT and X-ray. The data results were analyzed using SPSS19.0 statistical software package.ResultsThe distribution of bone cement in different reinforcement groups was different and showed regularity. The bone cement in the 4-hole group was roughly located in the head 1/3 of the screw, the 6-hole group was located in the middle 1/3 of the screw, and the 8-hole group was located in the caudal 1/3 of the screw. Compared with the control group, the maximum axial pull-out force of screws in the lateral hole and full screw tunnel reinforcement group was significantly increased. There was no significant difference between the 4-hole, 6-hole and straight pore groups. There was no difference in the screw-in torque between the reinforcement groups, and they all increased significantly compared with the control group, and the difference was statistically significant. After the screw was pulled out, the interface between the bone cement and the polyurethane material was fractured, and a tight package was formed with the screw.ConclusionsEnhancer syringes with different hole numbers combined with CPC bone cement injection can significantly increase the maximum screw pull-out force. The 8-hole group has a smaller pull-out force and is relatively prone to leakage of reinforcing material, which lacks safety in use. The local reinforcement of 4-hole and 6-hole sheath can play a similar role to that of total nail tunnel reinforcement.

Influence of Root Reinforcement on Shallow Landslide Distribution: A Case Study in Garfagnana (Northern Tuscany, Italy)

In this work, we evaluated the influence of root structure on shallow landslide distribution. Root density measurements were acquired in the field and the corresponding root cohesion was estimated. Data were acquired from 150 hillslope deposit trenches dug in areas either devoid or affected by shallow landslides within the Garfagnana Valley (northern Tuscany, Italy). Results highlighted a correlation between the root reinforcement and the location of measurement sites. Namely, lower root density was detected within shallow landslides, with respect to neighboring areas. Root area ratio (RAR) data allowed us to estimate root cohesion by the application of the revised version of the Wu and Waldron Model. Then, we propose a new method for the assimilation of the lateral root reinforcement into the infinite slope model and the limit equilibrium approach by introducing the equivalent root cohesion parameter. The results fall within the range of root cohesion values adopted in most of the physically based shallow landslide susceptibility models known in the literature (mean values ranging between ca. 2 and 3 kPa). Moreover, the results are in line with the scientific literature that has demonstrated the link between root mechanical properties, spatial variability of root reinforcement, and shallow landslide locations.

Numerical analysis on the lateral resistance and reinforcement of bolted glulam post and beam structures with local cracks

The lateral resistance of bolted glulam timber frame structural system is highly influenced by the mechanical performance of the moment-resisting connections, while local cracks are commonly observed in the bolted glulam connections with the restraint of steel fasteners to wood shrinkage. In this paper, a three-dimensional finite element model was established in business software ANSYS to investigate the influence of cracks on the cyclic behavior of moment-resisting bolted glulam connections and the strengthening effect of friction dampers installed in pre-cracked connections. The numerical model was validated by comparison with full-scale experimental results. Furthermore, a nonlinear numerical model was developed for the glulam timber post and beam structures, and comprehensive analysis was conducted to explore the effect of the number and location of pre-cracked connections and the application of friction dampers on the lateral performance of framed structures. It was found that with local cracks set in the moment-resisting connections, the lateral stiffness and capacity of the framed structures can be reduced by 27% and 30%, respectively. With the installation of friction dampers in pre-cracked connections, the lateral capacity and energy dissipation capacity of the reinforced frame can be up to 1.36 and 2.77 times that of initially perfect frame.

A Feasibility Study on the Lateral Behavior of a 3D-Printed Column for Application in a Wind Turbine Tower

Although 3D printing technology has been applied worldwide, the problem of connecting a printed structure and a foundation has rarely been examined. In particular, loads in the horizontal direction, such as wind loads and earthquake loads, can significantly affect the stability of a printed structure. Therefore, in this study, the effect of lateral loads on printed columns that were connected to a foundation by two types of connectors was investigated. A steel angle with bolts and couplers was used to connect the printed column to a concrete footing. In addition, two types of lateral reinforcement were applied to the printed column to enhance its bonding strength and shear resistance. The lateral reinforcements were attached to the interface of the printed layers at distances of 100 and 200 mm to investigate the effect of lateral reinforcement distance on the lateral behavior of the printed column. The results showed that the use of couplers as connections between the columns and foundation significantly improved the load capacity. Furthermore, the effects of the lateral reinforcement types and lateral reinforcement distances were assessed.

Effect of Lateral Reinforcement Densification on the Axial Load Capacity of Reinforced Concrete Columns

Effect of Lateral Reinforcement Densification on the Axial Load Capacity of Reinforced Concrete Columns

Introducing Skeletally-Mature Anterior Cruciate Ligament Reconstruction Technique Using Reinforcement (SATURN) With Iliotibial Band Autograft

Anterior cruciate ligament (ACL) injuries are increasingly common in the adolescent age group. Recent literature has endorsed combining ACL reconstruction with lateral extra-articular procedures to minimize residual rotatory knee instability and reduce the risk of reinjury in this age group. This technique describes a single-bundle combined anatomical ACL reconstruction and lateral extra-articular reinforcement performed with a single iliotibial band autograft. Also this technique allows for the ACL reconstruction and lateral extra-articular stabilization to be performed through a single surgical incision while obtaining autograft tissue without disruption of the extensor or hamstring mechanisms.

Comparing physical and statistical landslide susceptibility models at the scale of individual trees

Physically or statistically based approaches are widely used to quantify shallow landslide susceptibility. Despite the underlying data, methods, and assumptions being significantly different, there has been little quantitative work to evaluate the differences in model outcomes. Therefore, we compare a previously developed physical and a statistical shallow landslide susceptibility model for a study area in New Zealand's silvopastoral hill country. Both models include individual tree effects on slope stability. To identify individual trees for both models, we use convolutional neural networks to delineate tree crowns and classify species at the scale of individual trees with regional aerial photography. SlideforMAP, a physically based probabilistic model that includes both lateral and basal root reinforcement, is adapted for application in silvopastoral landscapes. Root reinforcement models for physical modelling are subsequently developed for the most abundant tree classes based on allometric relationships to remotely sensed, above-ground metrics. In contrast, the statistical landslide susceptibility model uses binary logistic regression, including empirically derived individual tree influence models alongside topographic and lithological explanatory variables. Binary logistic regression displays a better performance (AUC of 0.911 and 0.936 vs. 0.871 and 0.826) for our study area, resulting from the model being trained and tested on an inventory of past shallow landslide observations, whereas SlideforMAP makes predictions largely independent of past slope failures. SlideforMAP has the advantage of computing shallow landslide susceptibility for different rainfall scenarios coupled with specific return periods. The two predictions of landslide susceptibility within the study area were > 70 % in agreement. Differences in the model predictions are due to the different assumptions and datasets used by the models. Important considerations for land management include recognizing the advantages and limitations of both approaches in relation to erosion control objectives. We argue that the contrast afforded by the two different approaches to slope stability modelling in terms of assumptions, methods, and spatial predictions can increase process understanding, since – while being different – both approaches are geomorphologically plausible. However, to increase performance of erosion and sediment mitigation, we suggest land managers prioritize tree planting in areas where the statistical and physical approach agree within the “high” susceptibility classification (8 % of the study area). Comparing shallow landslide susceptibility scenarios based on potential trees and a treeless baseline can further improve targeted planting.

Numerical evaluation of axial compressive behavior of hollow concrete columns reinforced with GFRP bars and spirals

AbstractWith the advancement in the concrete technology, the application of precast concrete elements in the buildings and road infrastructures is increasing very rapidly. One of such applications is the use of precast hollow concrete elements in the bridge construction. As the conventional steel reinforcement is highly susceptible to corrosion, the use of non‐corrosive reinforcement in precast hollow concrete piers and piles of bridges could be a good option for the durability of bridge structures., In this regard, hollow concrete columns reinforced with fiber‐reinforced polymer (FRP) have been considered as a potential solution to overcome the structural deterioration due to corrosion. In the past, limited studies have been carried out on hollow concrete columns reinforced with FRP, consequently, the behavior of such columns is not fully understood. Therefore, to comprehensively evaluate the behavior of hollow concrete columns for various design parameters, a finite element model (FEM) was developed in this study using the commercial tool “Abaqus”. The model was developed and verified based on the experimental results of studies conducted by two independent research groups on circular concrete columns. The proposed model well predicted the peak loads with an error less than 10% and the failure modes of the tested columns. The verified constitutive relation and establishing method were further employed to conduct parametric evaluations to observe the influence of different parameters, such as inner‐to‐outer diameter ratio, longitudinal reinforcement ratio, lateral reinforcement ratio, and concrete strength, on the behavior of hollow concrete columns. Parametric analyses show that reduced inner‐to‐outer diameter ratio and larger longitudinal or lateral reinforcement may lead to higher peak load and confined concrete strength. Finally, based on the experimental and FEM evaluations, the strength prediction equations were developed for the analysis and design of hollow concrete columns reinforced with GFRP bars.

Use of Welded Wire Reinforcement as Lateral Reinforcement in Concrete Beams: Part 2—Flexure

Use of Welded Wire Reinforcement as Lateral Reinforcement in Concrete Beams: Part 2—Flexure

Use of Welded Wire Reinforcement as Lateral Reinforcement in Concrete Beams: Part 1—Shear

Use of Welded Wire Reinforcement as Lateral Reinforcement in Concrete Beams: Part 1—Shear