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This work examines the performance of reinforced concrete (RC) beams strengthened using bonded steel wire rope (SWR) at various prestressing levels. The strengthening approach has, however, been applied to the flexural strengthening of RC T-beams in the negative moment region, in order to determine its advantages. For this purpose, four RC T-beams were fabricated and tested under monotonic four-point bending: one control beam (S00), one beam strengthened with non-prestressed SWR (S20), and two beams strengthened with SWR (prestressed at 10% and 20% of their ultimate tensile strength: S21 and S22). The results indicate that the strengthened beams exhibit higher load-carrying capacities. Specifically, the cracking load, yield load, and ultimate load of S20, S21, and S22 increase by 10%–30%, 30%–50%, and 50%–90%, respectively, compared to S00. Additionally, there is an improvement in stiffness and energy absorption capacity. However, these strategies may have a dual effect on the specimens, resulting in a reduction in their ductility index. Finally, the tested beams were replicated using a three-dimensional finite element model, which has proved effective in predicting the behavior of such structures and, therefore, was found to be appropriate for use in future studies. [ABSTRACT FROM AUTHOR]

The width‐thickness requirement for highly ductile built‐up box columns in AISC 341‐22 is conservative when comparing the hysteretic responses of highly ductile box columns and I‐shaped columns. This study aimed to assess the seismic performance of moderately ductile box columns in a 3‐story steel dual frame with a buckling‐restrained braced frame (BRBF) and a special moment frame (SMF). The frame specimen was configured in phase 1 testing to allow the slabs to slide relative to the steel frame; Teflon pads were provided between the slabs and steel beams, and horizontal buckling‐restrained braces (BRBs) were installed between the slabs and steel beams. In phase 2, the horizontal BRBs were replaced by rigid links such that the frame specimen simulated a conventional construction. Two phases with 17 shake table tests were conducted on the frame specimen. A near‐fault motion record, obtained from the 2022 Chihshang earthquake, was used as an input motion. In phase 1, test results showed that the slab sliding system was effective in reducing the floor acceleration by 25% when compared to the rigid slab frame system. In phase 2, the base of moderately ductile built‐up box columns still performed well without local buckling even when the interstory drift angle reached 0.045 rad. Postearthquake tests were conducted on the all‐steel, first‐story BRB that was removed from the building specimen after all shake table tests. A higher‐mode buckling of the core plate was observed at both ends of the core, causing a minor strength increase at the end of the test. [ABSTRACT FROM AUTHOR]

In this study, disintegrated bamboo fibers (DBFs) were extracted from alkali-treated makino bamboo sticks (BSs). The chemical compositions and tensile properties of DBFs were investigated using Fourier transform infrared (FTIR), X-ray diffraction (XRD), thermogravimetric (TG) analysis, and tensile tests. The results indicated that a change in functional groups, a reduction in the crystallinity index, and better thermal stability were observed for DBFs than for BSs. Regardless of the collapse of parenchyma cells and separation and twist of the fibers on the surface of the DBF, its average tensile strength and tensile modulus were 204 MPa, and 13 GPa, respectively. Additionally, DBFs were added into a cement matrix to fabricate bamboo fiber/cementitious composites (BCCs). The apparent density and most of the mechanical properties of BCCs decreased when the addition of the DBFs increased above 1 wt%. However, the BCC with 1 wt% of DBFs showed the lowest drying shrinkage and a slight increase in the specific energy under tensile testing. Accordingly, the results showed that 1 wt% DBFs as an adequate content is proposed to be added into the cement. [ABSTRACT FROM AUTHOR]

The CoCrFeMnNi high entropy alloys remain an active field over a decade owing to its excellent mechanical properties. However, the application of CoCrFeMnNi is limited because of the relatively low tensile strength. Here we proposed a micromechanical model which adopted from the theory of dislocation density to investigate the strengthening mechanisms of precipitation of chromium-rich non-equiatomic CoCrFeMnNi alloy. The microstructures of CoCrFeMnNi were obtained directly from SEM-BSE images with different annealing temperatures. The proposed framework is validated by comparing simulations with experiments of uniaxial tensile tests on the CoCrFeMnNi alloys under different annealing temperatures. The stress–strain curves indicate that the precipitate has greater influence on post-yield hardening than the initial yielding strength. In addition, we identified that the particle distribution, controlled by the average size of the particle and the volume fraction of precipitation, can significantly enhance the strengthening effect. The numerical results indicate that HEAs with a precipitate distribution closer to a normal distribution and with smaller average size will tend to have higher strength and ductility. [ABSTRACT FROM AUTHOR]

The use of carbon fiber-reinforced polymer (CFRP) rods offers a good solution for external strengthening of flexural reinforced concrete (RC) members. Limited data are available on the behavior of beams externally reinforced with CFRP rods under a loading–unloading protocol, which is of great importance for structural components subjected to vehicle loading. The embedment depth mandated by the majority of standards cannot always be acquired due to concrete cover limitations; the influence of embedment depth under this loading–unloading sequence needs to be investigated. This research studied the effects of rod embedment depth by comparing fully-embedded rods with half-embedded rods under a loading–unloading protocol and comparing the results with monotonic responses. An identical specimen without CFRP reinforcement functioned as the controlling element. The near-surface mounted technique (NSM) was used to integrate the rods with the concrete. The results show that CFRP rods positively affect the load-carrying capacity under a loading–unloading condition. The rods reduce the member's ductility under monotonic loading but have no negative impact under loading–unloading. Whereas the difference in embedment depth configuration slightly affected the enhancement under monotonic loading, the half-embedded rods drastically reduced the capacity improvement under the loading–unloading sequence. An embedment depth deviating from the advised depth, should not be implemented for members subjected to a loading–unloading condition. The CFRP placement method had an impact on the failure behavior of the elements. The half-embedded rod failed by debonding between the rod and the epoxy resin, while the fully-embedded members were characterized by concrete spalling. [ABSTRACT FROM AUTHOR]

The management strategies of thoracolumbar (TL) burst fractures include posterior, anterior, and combined approaches. However, the rigid constructs pose a risk of proximal junctional failure. In this study, we aim to systemically evaluate the biomechanical performance of different TL reconstruction constructs using finite element analysis. Furthermore, we investigate the motion and the stress on the proximal junctional level adjacent to the constructs. We used a T10-L3 finite element model and simulated L1 burst fracture. Reconstruction with posterior instrumentation (PI) alone (U2L2 and U1L1+(intermediate screw) and three-column spinal reconstruction (TCSR) constructs (U1L1+PMMA and U1L1+Cage) were compared. Long-segment PI resulted in greater global motion reduction compared to constructs with short-segment PI. TCSR constructs provided better stabilization in L1 compared to PI alone. Decreased intradiscal and intravertebral pressure in the proximal level were observed in U1L1+IS, U1L1+PMMA, and U1L1+Cage compared to U2L2. The stress and strain energy of the pedicle screws decreased when anterior reconstruction was performed in addition to PI. We showed that TCSR with anterior reconstruction and SSPI provided sufficient immobilization while offering additional advantages in the preservation of physiological motion, the decreased burden on the proximal junctional level, and lower risk of implant failure. [ABSTRACT FROM AUTHOR]

The old existing reinforced concrete (RC) structures in Taiwan are susceptible to severe damage under earthquakes because of the soft-story mechanism. Moreover, the effects of near-fault ground motions often contain a long period of velocity pulse and permanent ground displacement. This study is based on the tri-axial shaking table test conducted at the National Center for Research on Earthquake Engineering in Taiwan and a series of seismic performance evaluations of a non-ductile RC structure in Taiwan. Finite element analysis (FEA) will be conducted to simulate the linear and nonlinear behavior of the seven-story building. This accommodates the damage plasticity model for concrete and the elastic-perfectly plastic model for reinforcement. Comparison of the results between the experimental test and numerical model showed that the similarity of the vibration period has a great influence on the simulation results. The findings showed that the data of acceleration and displacement behavior corresponded with the experimental results in a satisfactory margin. Also, the damage mode is very similar to the shaking table test results. The study found that using FEA can satisfactorily simulate the seismic performance of mid-rise buildings under a near-fault earthquake. [ABSTRACT FROM AUTHOR]

Finite element analysis has been commonly used in many studies to examine the performance of structural elements. The objective of this article is to assess the relevance of geometric and strengthened pattern uncertainty on prestressed reinforced concrete beams strengthened by fiber-reinforced plastics based on a nonlinear finite element analysis. The parametric study focuses on the significant effects of fiber-reinforced polymer, beam length, and prestressed load on the ultimate loading capacity of the prestressed reinforced concrete beam strengthened by fiber-reinforced plastics. The results demonstrate the advantages of fiber-reinforced plastics that significantly increase the stiffness and the ultimate loading capacity of prestressed reinforced concrete beams. It is found that the beams that are strengthened by the FRP with fibers oriented at 0° have better results than other orientation angles. [ABSTRACT FROM AUTHOR]

Background: Semi-rigid lumbar fusion offers a compromise between pedicle screw-based rigid fixation and non-instrumented lumbar fusion. However, the use of semi-rigid interspinous stabilization (SIS) with interspinous spacer and ligamentoplasty and semi-rigid posterior instrumentation (SPI) to assist interbody cage as fusion constructs remained controversial. The purpose of this study is to investigate the biomechanical properties of semi-rigidly stabilized lumbar fusion using SIS or SPI and their effect on adjacent levels using finite element (FE) method.Method: Eight FE models were constructed to simulate the lumbosacral spine. In the non-fusion constructs, semi-rigid stabilization with (i) semi-rigid interspinous spacer and artificial ligaments (PD-SIS), and (ii) PI with semi-rigid rods were simulated (PD + SPI). For fusion constructs, the spinal models were implanted with (iii) PEEK cage only (Cage), (iv) PEEK cage and SIS (Cage+SIS), (v) PEEK cage and SPI (Cage+SPI), (vi) PEEK cage and rigid PI (Cage+PI).Result: The comparison of flexion-extension range of motion (ROM) in the operated level showed the difference between Cage+SIS, Cage+SPI, and Cage+PI was less than 0.05 degree. In axial rotation, ROM of Cage+SIS were greater than Cage+PI by 0.81 degree. In the infrajacent level, while Cage+PI increased the ROM by 24.1, 27,7, 25.9, and 10.3% and Cage+SPI increased the ROM by 26.1, 30.0, 27.1, and 10.8% in flexion, extension, lateral bending and axial rotation respectively, Cage+SIS only increased the ROM by 3.6, 2.8, and 11.2% in flexion, extension, and lateral bending and reduced the ROM by 1.5% in axial rotation. The comparison of the von Mises stress showed that SIS reduced the adjacent IVD stress by 9.0%. The simulation of the strain energy showed a difference between constructs less than 7.9%, but all constructs increased the strain energy in the infradjacent level.Conclusion: FE simulation showed semi-rigid fusion constructs including Cage+SIS and Cage+SPI can provide sufficient stabilization and flexion-extension ROM reduction at the fusion level. In addition, SIS-assisted fusion resulted in less hypermobility and less von Mises stress in the adjacent levels. However, SIS-assisted fusion had a disadvantage of less ROM reduction in lateral bending and axial rotation. Further clinical studies are warranted to investigate the clinical efficacy and safety of semi-rigid fusions. [ABSTRACT FROM AUTHOR]

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Copyright of Journal of Zhejiang University: Science A is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The fundamental natural frequency of rectangular symmetrically laminated plates with a given material system is maximized with respect to fiber orientations by using a sequential linear programming method together with a simple move-limit strategy. Significant influence of plate thickness, aspect ratio, circular cutout and end conditions on the optimal fiber orientations and the associated optimal fundamental natural frequency of fiber-reinforced laminated composite plates has been shown through this investigation. [ABSTRACT FROM PUBLISHER]

Based on linear and nonlinear in-plane shear formulations for fiber- composite laminate materials, finite-element buckling analyses for composite plates under uniaxial compression and biaxial compression and for composite shells under end com pression and hydrostatic compression are presented. It has been shown that the nonlinear in-plane shear has significant influence on the buckling and postbuckling responses of composite plates and shells, specially for those with [45/-45]2S layup. [ABSTRACT FROM PUBLISHER]