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To study the seismic performance of self-centering circular-section rocking steel bridge piers whose functions can be restored after an earthquake, a high-precision finite element (FE) analysis model of such a bridge piers was established. The hysteresis behavior of concrete-infilled and hollow rocking steel bridge piers was compared. In response to the characteristics of the local deformation of the wall plates and elliptical deformation of the bottom surface, two reinforcement methods for the pier bottom, namely thickening the wall plate and adding longitudinal stiffeners in the plastic zone of the pier bottom, were proposed. The pseudo static analysis of bridge piers was carried out considering the effects of overall design parameters and reinforcement parameters of the pier bottom. The results indicate that the FE model used in this paper can obtain accurate horizontal load-displacement curves of rocking steel bridge piers. The hysteresis curves of the rocking steel bridge piers and infilled concrete rocking steel bridge piers is close, and directly using hollow steel bridge piers can improve the economic efficiency of the design. Compared to adding longitudinal stiffeners, the reinforcement form of thickened wall plates at the pier bottom has a better effect in improving the seismic performance of bridge piers. The reinforcement of the pier bottom has little effect on the energy dissipation capacity of the bridge pier, but it helps to reduce residual displacement and improve lateral stiffness. [ABSTRACT FROM AUTHOR]

Concrete 3D Printing (3DP) is a potential technology for increasing automation and introducing digital fabrication in the construction industry. Concrete 3D Printing provides a significant advantage over conventional or precast methods, such as the prospects of topologically optimized designs and integrating functional components within the structural volume of the building components. Many previous studies have compiled state-of-art studies in design parameters, mix properties, robotic technologies, and reinforcement strategies in 3D printed elements. However, there is no literature review on using concrete 3D Printing technology to fabricate structural load-carrying elements and systems. As concrete 3DP is shifting towards a large-scale construction technology paradigm, it is essential to understand the current studies on structural members and focus on future studies to improve further. A systematic literature review process is adopted in this study, where relevant publications are searched and analyzed to answer a set of well-defined research questions. The review is structured by categorizing the publications based on issues/problems associated with structural members and the recent technology solutions developed. It gives an overall view of the studies, which is still in its nascent stage, and the areas which require future focus on 3D printing technology in large-scale construction projects.

The deformation of variable cross-section at the emergency parking belt in soft rock mass highway tunnel is significant than that of the normal section. The deformation related disasters are prone to occur, which is difficult to maintain normal construction in soft rock mass highway tunnels. By taking the Muzhailing Highway tunnel in the section from Weiyuan to Wudu as the research object, the deformation and failure characteristics of variable cross-section at the emergency parking belt was summarized and analyzed. On this basis, the prestressed anchor cable with small diameter was proposed to reinforce the rock mass. The excavation process of variable cross-section was simulated by using FLAC3D finite difference software. The deformation control effects of different reinforcement schemes were compared, and the support effect of selected scheme was verified by field test. The research results show that the deformation of rock mass on the sudden-change side was obviously larger than that on the other side in the range of 15 m at the variable cross-section, when the tunnel was constructed from the emergency parking belt to the normal section. The maximum deformation occurred at the arch foot of the upper bench and the shotcrete cracking, distortion of steel ribs and local deformation intrusion occurred. The rock mass on the sudden-change side has been disturbed many times by the blasting construction. Meanwhile, the restraint of the support structure on the end of the emergency parking belt was weak and the rock mass was softened by groundwater. These were the reasons for the large deformation of rock mass on the sudden-change side. By adopting longitudinal prestressed anchor cable +circumferential prestressed anchor cable to reinforce rock mass at the end of emergency parking belt, the stability of rock mass was enhanced and the deformation was basically symmetrical. The research results provided an important reference for the deformation control of variable cross-section at the emergency parking belt of soft rock mass highway tunnel. [ABSTRACT FROM AUTHOR]

To study the seismic performance of self-centering circular-section rocking steel bridge piers whose functions can be restored after an earthquake, a high-precision finite element (FE) analysis model of such a bridge piers was established. The hysteresis behavior of concrete-infilled and hollow rocking steel bridge piers was compared. In response to the characteristics of the local deformation of the wall plates and elliptical deformation of the bottom surface, two reinforcement methods for the pier bottom, namely thickening the wall plate and adding longitudinal stiffeners in the plastic zone of the pier bottom, were proposed. The pseudo static analysis of bridge piers was carried out considering the effects of overall design parameters and reinforcement parameters of the pier bottom. The results indicate that the FE model used in this paper can obtain accurate horizontal load-displacement curves of rocking steel bridge piers. The hysteresis curves of the rocking steel bridge piers and infilled concrete rocking steel bridge piers is close, and directly using hollow steel bridge piers can improve the economic efficiency of the design. Compared to adding longitudinal stiffeners, the reinforcement form of thickened wall plates at the pier bottom has a better effect in improving the seismic performance of bridge piers. The reinforcement of the pier bottom has little effect on the energy dissipation capacity of the bridge pier, but it helps to reduce residual displacement and improve lateral stiffness.

Developing sustainable high-performance bamboo-based composites (HPBBC) with carbon sequestration benefits as reinforcement material is of great significance in promoting the application of HPBBC and securing ancient wooden buildings. Available column reinforcement methods have damage characteristics, which are unsuitable to be applied in ancient wooden columns because the ancient building needs to be preserved in the current conditions. The wooden column was bound with HPBBC and spaced steel strips to achieve damage-free strengthening. The slenderness ratio is an essential factor affecting the mechanical properties of wood poles, which is significant to be studied. The effect of the slenderness ratio on the axial compression behavior of circular wood columns strengthened with HPBBC was investigated in this study. The test results showed that the slenderness ratio significantly influences the failure mode, load-bearing capacity, and deformability of strengthened circular wood columns. The typical failure mode of short columns was a crushing failure, while the long columns were buckling failures. The load-carrying capacity and longitudinal strain of strengthened circular timber columns decrease significantly with increasing slenderness ratio. The lateral displacements or buckling appearance increases significantly with the increasing slenderness ratios of the strengthened timber column. A load-bearing capacity formula was proposed to predict the load capacity of strengthened circular wood columns based on their axial compression damage characteristics. The error between the calculated and tested results is less than 8.2 %. • High-performance bamboo-based composites (HPBBC) as reinforced materials. • Wood columns are strengthened with HPBBC by spacing steel strips. • Effect of slenderness ratio on circular wood columns strengthened with HPBBC. • A modified buckling formula is proposed. [ABSTRACT FROM AUTHOR]

Copyright of Association of Arab Universities Journal of Engineering Sciences (JAARU) is the property of Association of Arab Universities 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.)

Abstract Mechanized tunneling, like other tunneling methods, is not an exception to dealing with complex geological structures in its direction. Therefore, the accurate perception of the geological structures and anomalous through the tunnel path and the challenges ahead of TBM can minimize the operational risk. The faults are complicated, loose, seismic, and saturated structures that present a great deal of danger when passing the tunnel from them, and each of these events, in turn, has the potential to stop the project and exert high economic costs. The instability of the tunnel environments and tunnel face due to the higher amount of stress concentration than the resistance of the host rock, pulpy material flowing from inside of the faults and water inrush are the most important events that TBM faced them through the fault zones. Hence, using the appropriate tool for realizing the operational model can be a considerable help in predicting problems. In this research, using precision numerical methods, accurate simulation of TBM motion was carried out to the excavation of Water Transmission Tunnel, Iran. The Safaroud water transmission tunnel is one of the longest Iranian water transmission tunnels that passes through numerous fault zones along its path. One of the main faults in this area is the Lalehzar fault with 40 m width which motivates us to utilize predicting procedure. The main purpose of this research is numerical modeling of mechanized tunneling in fault zone using FLAC3D and Phase2 software and selection of suitable reinforcement strategies for passing TBM from the fault zone. The results of numerical modeling illustrate the instability of the tunnel in the Lalehzar fault zone. Due to tunnel instability in this zone, reinforcement operations must be taken into account to stabilize the tunnel environment. The numerical modeling of the several reinforcement operations in the fault zone were simulated and we conclude that the combination of umbrella arch and radial grouting method are the most suitable strategies for passing TBM from the Lalehzar fault zone. [ABSTRACT FROM AUTHOR]

The effect of blasting vibration on the macroscopic failure characteristics of underground tunnels has been investigated, but little attention has been paid to the stress and deformation characteristics of underground tunnels under the combined action of explosion waves and in-situ stresses. Consequently, enhancing the bearing capacity of surrounding rock masses by adopting effective reinforcement measures is an urgent problem that needs to be solved. Due to high in situ stresses at great depths, it is difficult to conduct field tests on various reinforcement methods. In this study, using the deep underground tunnels as a prototype, large-scale physical model tests were adopted to examine the stress and deformation characteristics of the unlined tunnels, the rock bolt reinforced tunnels, and the lined tunnels under the coupling action of in-situ stress and blasting waves induced by different charge quantities, with the purpose of providing the necessary theoretical and technical support for the design and support of deep protective engineering. [ABSTRACT FROM AUTHOR]

Recent clinical trial studies have demonstrated that the effects of acupuncture on pain improvement are small and no difference between acupoints and non-points. Whether acupuncture needles must be inserted in specific points depends on whether acupoint specificity exists that is still not resolved, and is now urgent. Previous anatomical studies have demonstrated that acupoints exist higher number of nerve fibers/trunks, blood vessels, hair follicles, and sweat glands as well as density of the gap junction. Recent evidence shows that nitric oxide (NO) level is elevated in the acupoints/ meridians and is associated with an enhanced expression of NO synthase endowed with transient receptor potential vanilloid type-1. There is growing evidence from international groups showing that acupuncture induces NO-mediated vasodilatation, which increases local blood flow and allows for a flush of algesic or sensitizing substances, leading to pain relief. Previous studies, using a novel biocapture system, have demonstrated that NOx (total nitrite and nitrate) and cyclic guanosine monophosphate (cGMP) concentrations are consistently increased over skin acupoints compared to non-meridian control regions (NMCR) in humans. Dermal microdialysis in humans showed that NO-cGMP releases in the subcutaneous tissue of acupoint are higher than those in NMCR and increased by electroacupuncture (EA). Recent studies have demonstrated that low-frequency electrical stimulation and manual acupuncture with low stimulating force and rate produce an elevation of NO release predominantly over acupoints. In contrast, NO levels over the areas of the skin regions are moderately reduced by high-frequency EA stimulation. The results from anatomical and biochemical studies consistently show that acupoints exist higher levels of NO signaling molecules, and stimulus-evoked NO release is also with a higher level at acupoints. Results suggest that NO signaling molecules contribute to the specificity of acupoints, and selecting well-trained acupuncturetists for using correct acupoints and appropriate parameters should improve acupuncture clinical trial studies. [ABSTRACT FROM AUTHOR]

Masonry infill walls serve as building partitions and are generally considered non-structural components. Their weights are considered in progressive collapse analysis, but the resistance of the infill walls is normally ignored in design standards. Based on the reasonable selection of constitutive models, a refined finite element (FE) model for the collapse resistance of concrete-filled steel tubular (CFST) composite frame with infill walls was established by ABAQUS/Explicit. Cohesive elements were inserted between different masonry blocks to simulate the mortar joints. The collapse resistance contribution and reinforcement methods analysis of the CFST frame with infill walls were carried out based on the validated FE models. Results show that the infill walls significantly contribute to resisting vertical load in the initial loading stage, with a maximum contribution of 55.3%. The infill walls, which are treated as the equivalent compressive struts, change the load-resisting path and effectively improve the load redistribution ability of the frame. The V-type oblique arrangement of tie rebars has better tie effect and collapse resistance of the frame than other arrangements. After pasting the CFRP sheet and spraying the ECC material to reinforce infill walls, the peak load can be increased by 25.1% and 22.9% respectively, and the ultimate load can be increased by 96.2% and 74.5% respectively. X-type pasting the CFRP sheet reinforcement has a better collapse resistance than others. Furthermore, based on the simplification of the infill walls as the diagonal struts, the simplified calculation formulas of anti-collapse capacity of CFST frame with infill walls were studied. • Numerical models are established for the collapse of CFST frame with infill walls. • Infill walls change the load-resisting path and improve the load redistribution. • The reinforcement methods of the CFST frame with infill walls are investigated. • Simplified prediction method for the anti-collapse capacity is proposed. [ABSTRACT FROM AUTHOR]

Copyright of Bulletin of Engineering Geology & the Environment 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.)

Over the last few years, fused filament fabrication (FFF) has become one of the most promising and widely used techniques for the rapid prototyping process. A number of studies have also shown the possibility of FFF being used for the fabrication of functional products, such as biomedical implants and automotive components. However, the poor mechanical properties possessed by FFF-processed products are considered one of the major shortcomings of this technique. Over the last decade, many researchers have attempted to improve the mechanical properties of FFF-processed products using several strategies—for instance, by applying the short fiber reinforcement (SFR), continuous fiber reinforcement (CFR), powder addition reinforcement (PAR), vibration-assisted FFF (VA-FFF) methods, as well as annealing. In this paper, the details of all these reinforcement techniques are reviewed. The abilities of each method in improving tensile, flexural, and compressive strength are discussed. [ABSTRACT FROM AUTHOR]