Peak Shear Stress Research Articles

Relationship between hand-foot skin reaction and external force on patients with hepatocellular carcinoma: A cohort study

PurposeHand-foot skin reaction (HFSR), a side effect of tyrosine kinase inhibitor (TKI) treatment, makes it difficult to walk and perform daily activities because of pain in the limbs. HFSR occurs predominantly in the sites where external forces (pressure and shear stress) are applied. This study aimed to determine whether pressure or shear stress induces the occurrence of HFSR. MethodsThis cohort study was conducted in patients who received TKI treatment for hepatocellular carcinoma. The external forces applied to the sole of the patients' foot while walking was measured, and its association with the occurrence of HFSR was examined. The degree of HFSR was assessed by the patient's response during the examination and by photographs of their feet. The patients' feet were divided into low (grade <2) or high (grade ≥2) HFSR foot group, and the differences in external forces between the groups were analyzed using t-test and Cox hazard analysis. ResultsAnalysis of the feet of 55 study participants (n = 110) showed no significant difference between the groups on t-test (p ≥ 0.05), however, Cox hazard analysis showed an increased risk of HFSR with higher peak shear stress values at the fifth metatarsal head (hazard ratio = 1.01, p = 0.047; 95% confidence interval = 1.00–1.02). ConclusionShear stress is possibly related to HFSR occurrence. Nurses should assess whether patients' shoes fit their feet before initiating TKI treatment. They should instruct patients to wear shoes that are fit of both diameter and width for their feet.

Effects of Shear Characteristics of Anchoring Interface on Bearing Performance of Fully Grouted Bolts Based on Variable Controlling Method

The shear strength parameter of an anchoring interface is one of the key parameters affecting the design of bolt support. To better realize the design of bolt support, the pullout model of fully grouted bolts was established by FLAC3D numerical software. The commonly used tri-linear bond-slip model of the anchoring interface was selected. The variable controlling method was used to investigate the effects of the shear strength parameters of the anchoring interface on the bearing performance of fully grouted bolts. The results show that, with the increase in the displacement at the peak shear stress, the bearing capacity and the energy absorption of fully grouted bolts decrease and the ability of the fully grouted anchoring system to resist external loads weakens. Meanwhile, the deformation capacity of fully grouted bolts increases, and the durability of the fully grouted anchoring system is enhanced. With the increase in the residual shear stress and the displacement at the residual shear stress, the bearing capacity and deformation capacity of fully grouted bolts both increase, and the energy absorption also increases. Increasing the post-peak bearing properties of the anchoring interface can help improve the bearing performance of fully grouted bolts and enhance the ability of the fully grouted bolts to resist failure. The results may provide guidance for support design and performance enhancement of fully grouted bolts.

Investigation on strength characteristics of fly ash treated dredged marine clay with various pore water salinities

This study investigated the strength characteristics of dredged marine clays treated with fly ash with varying porewater salinities. A series of laboratory tests were conducted on fly ash-treated dredged marine clay specimens with various salinities and curing times. In the direct shear tests, observed patterns revealed a consistent initial rapid increase in shear stress with the increase of horizontal displacement, followed by either a gradual decline or stabilization after reaching the peak shear stress. The variation curve consistently positioned the lower salinity or longer curing time above the higher salinity or shorter curing time. Furthermore, the shear strength at a given vertical stress consistently decreases with increasing salinity while ascending with increasing curing time. This indicated that curing time positively influences shear strength development, while the presence of salt negatively affects it. Both strength parameters cohesion and friction angle exhibited growth trends with increased curing time but displayed a decline as salinity increased from 0% to 6%. Unconfined compressive strength test results showed a strain-softening behavior for all tested specimens. The compressive strength demonstrated a declining trend with rising salinity, with a more pronounced decrease observed within the initial 7d compared to the less significant change between 7d and 28d.

Experimental Study on Cyclic Shear Performance of the Four-Way Geogrid Reinforcement–Soil Interface

This paper presents the results of horizontal cyclic direct shear tests at the reinforced soil interface of a four-way polypropylene geogrid reinforced sandy soil. The influence of normal stress and shear displacement amplitude on the shear stress, shear stiffness, and damping ratio of the reinforced soil interface are evaluated by varying the normal stress and shear displacement amplitude. Dynamic shear characteristics of reinforced soil interface under normal constant load were investigated by using a large dynamic straight shear apparatus. Peak interface strength increases with increasing amplitude of normal stress and shear displacement amplitude. The larger the normal stress and shear displacement amplitude, the fewer cycles are needed to attain peak interface strength. At low-magnitude normal stress levels, the peak shear stress and shear stiffness tend to stabilize after an initial increase during the cycling process, and the damping ratio decreases and then stabilizes with the increase in the number of cycles; whereas when the normal stress level is high, the peak shear stress and shear stiffness increase and then decrease during the cycling process and eventually stabilize, and the damping ratio decreases and then increases and finally stabilizes with the increase in the number of cycles. Moreover, under the same number of cycles, the corresponding shear stiffness decreases with an increase in shear displacement amplitude, while the damping ratio increases.

Experimental investigation of the compressive and shear behaviours of grouted and hollow masonry constructed with PVA fibre-reinforced mortar and grout

Polyvinyl alcohol (PVA) fibres are ultra-high-performance fibres that can be used to reinforce cementitious composites. This study experimentally investigated the compression and shear behaviours of grouted and hollow masonry constructed with fibre-reinforced mortar (FRM) used for the joints and/or PVA fibre-reinforced grout (FRG). In this regard, the effect of increasing the fibre content of 6 mm PVA fibres in the FRM on the behaviour of masonry was investigated. Moreover, the effect of changing the fibre length (8 mm and 13 mm PVA fibres) and the fibre content of 13 mm PVA fibres in the FRG on the behaviour of masonry was investigated. This was accomplished by constructing and testing 31 masonry prisms and 29 masonry assemblages. The behaviour of PVA-reinforced masonry was evaluated based on compressive strength, shear strength, modulus of elasticity, modulus of rigidity, compressive strain at peak compressive stress, shear strain at peak shear stress, compression ductility index and compression toughness. In addition, the compression and shear stress-strain curves, failure modes and crack propagation of PVA-reinforced masonry were compared with unreinforced masonry. It was concluded that using PVA fibres in the grout minimized the masonry face shell spalling, and most of the post-peak deterioration appeared in the form of masonry cracks and less face shell spalling compared with unreinforced masonry. In addition, using PVA-FRM only or PVA-FRM with PVA-FRG could increase the compressive strength of grouted masonry. In contrast, using PVA-FRM did not change the compressive strength of hollow masonry. Furthermore, all grouted assemblages with PVA-FRM and PVA-FRG (except for assemblages with 13 mm PVA-FRG with a fibre content of 0.10% by weight of grout) have similar average shear strength compared with unreinforced assemblages. Finally, As the fibre content of 6 mm PVA fibres in the FRM of hollow assemblages increased, the shear strength and the modulus of rigidity decreased. This study highlights the improvements and drawbacks of using PVA Fibres in mortar and grout on the compressive and shear performances of hollow and grouted masonry.

Shear fracture behavior and damage constitutive model of rock joints considering the effect of pre-peak cyclic loading

The research on mechanical properties and fracture nalysed of rock joints under dynamic loading disturbance is essential for the stability analysis of rock mass engineering. In this work, a series of pre-peak cyclic shear tests considering the number of cycles and cycle amplitude are conducted for rock joints. Firstly, the shear fracture nalysed and damage evolution law of rock joints are investigated in detail. Then, based on the statistical damage theory, the novel damage constitutive model of rock joints under pre-peak cyclic shear loading is established assuming that the microscopic element damage of rock joints material obeys the Weibull distribution. Finally, the real-time response of acoustic emission and the failure mode of joint surface are nalysed. The results demonstrate that the peak and residual shear stress are positively correlated with the cyclic amplitude. The cumulative cyclic displacement grows with the increase in the number of cycles and cycle amplitude. Moreover, the developed damage model considering the effect of pre-peak cyclic loading is verified by comparing the shear test results with the theoretical values, which are in good agreement. The variation of the shear wear zone of joint surface with cyclic parameters is discussed by binarization calculations. The results of this work can provide a valuable theoretical basis for further research on the shear fracture mechanism of rock joints under dynamic loading disturbance and mitigating geological disasters.

Counterface soil type and loading condition effects on granular/cohesive soil – Geofoam interface shear behavior

Soil – geofoam interfaces have been studied through an extensive experimental program by performing multiple series of interface shear tests using two different granular soils (i.e. beach sand and construction material sand) and one cohesive soil (i.e. bentonite clay) as well as a soil mixture containing 75% sand and 25% clay by dry weight at distinct loading conditions (i.e. normal stresses (σ): 25, 100, 250; low, moderate, high loading conditions, respectively). Using the shear stress versus horizontal displacement curves obtained, some important engineering design parameters including peak shear stress, residual shear stress, interface sensitivity (i.e., peak/residual ratio) and displacement required to reach peak stress have been determined and the variations in those interface mechanical properties as a function of loading condition and counterface soil type have been investigated. It was shown that the peak as well as residual shear stresses increased with an increase in normal stress for all the interface systems tested. Further, the granular soil (sand) interfaces demonstrated relatively larger frictional strengths (both peak and residual) as compared to both the cohesive soil (clay) interface and the sand/clay admixture soil interface. Additionally, the higher the angularity of granular soil particles became, the larger the interface shear strengths (peak and residual), when sheared against geofoams, developed in light of experimental results attained as a result of interface shear tests on different material combinations. For comparison, the detected peak strength at average for the construction material sand, the beach sand, and the sand/clay admixture soil interfaces as compared to the bentonite clay interface were improved 59.8%, 43.4%, and 20.3%, respectively. Additionally, the detected residual strength at average for the construction material sand, the beach sand, and the sand/clay admixture soil interfaces as compared to the bentonite clay interface were improved 53.9%, 28.6%, and 15.4%, respectively.

Numerical simulation of wall shear stress and boundary layer flow from jetting cavitation bubble on unheated and heated surfaces

The physics of wall shear stress and boundary layer flow from jetting cavitation bubbles on unheated and heated surfaces was investigated numerically using a homogeneous mixture model based on a fully compressible Navier–Stokes solver. A spatial–temporal shear stress map and velocity field on unheated surfaces under several standoffs were considered first. Complex boundary layer flow, including separation vortex caused by an adverse pressure gradient and the generation of a thermal boundary layer because of skin friction with the shear flow, was discussed in detail. The tendency of different maximum shear stress for each standoff section was discussed with liquid film thickness and jet velocity. Also, we suggested maximum shear stress correlation equation for minimum film thickness and wall impact pressure as dimensionless form. As an expansion of previous studies, we examined bubble collapse–induced wall shear stress on a heated surface under various surface temperatures. The peak shear stress decreased with the lower Prandtl number flow. In the collapse phase, surface cooling by downward microjet and heat transfer with ring vortex were also captured. Consequently, we suggested correlation equations for primary and secondary peak shear stresses as function of Prandtl number and confirmed that the boundary layer flow including heat transfer can be well simulated.

Experimental investigation on strength characteristics of marine soft clay under monotonic and cyclic loading

Sea areas with an average water depth of 5-15 m in the East China Sea are mostly muddy soft-foundation seabed. The wind power infrastructure built on them must fully consider the mechanical properties of marine soft clay during design process. In this study, monotonic and cyclic tests were conducted to study the strength characteristics of soft clay at various strain rates, cyclic stresses and initial effective vertical stresses using a simple shear apparatus. The test results showed that, as the strain rate increased, the peak shear stress of the samples under different confining pressures increased. However, the failure lines of the effective stress path of samples under different strain rates and vertical stresses are uniform. Compared to the traditional cyclic failure criteria, the failure criterion based on the inflection point of double amplitude strain can reflect the deformation characteristics of the specimen more accurately. The peak shear strength obtained from the monotonic tests was used to normalize the cyclic stress. Subsequently, the relationship between the number of failure cycles and normalized cyclic stress level of the soft clay specimens was established.

Effect of residual volume after surgery of the discoid lateral meniscus on tibiofemoral joint biomechanics: a finite element analysis

BackgroundThe purpose of this study was to investigate the influence of different residual meniscus volume on the biomechanics of tibiofemoral joint after discoid lateral meniscus (DLM) surgery by finite element analysis.MethodsA knee joint model was established based on CT and MRI imaging data. The DLM model was divided into five regions according to conventional meniscectomy, with volumes of 15%, 15%, 15%, 15%, 15%, and 40% for each region. Additionally, the DLM model was divided into anterior and posterior parts to obtain ten regions. The DLM was resected according to the design scheme, and together with the intact discoid meniscus, a total of 15 models were obtained. Finite element analysis was conducted to assess shear and pressure trends on the knee joint.ResultsThe study observed significant changes in peak shear stress and compressive stress in the lateral meniscus and lateral femur cartilage. As the meniscus volume decreased, there was an increase in these stresses. Specifically, when the meniscus volume reduced to 40%, there was a sharp increase in shear stress (302%) and compressive stress (152%) on the meniscus, as well as shear stress (195%) and compressive stress (157%) on the lateral femur cartilage. Furthermore, the model grouping results showed that preserving a higher frontal volume in the meniscus model provided better biomechanical advantages.ConclusionThe use of finite element analysis has demonstrated that preserving more than 55% of the meniscus volume is necessary to prevent a significant increase in joint stress, which can potentially lead to joint degeneration. Additionally, it is crucial to preserve the front volume of the DLM in order to achieve improved knee biomechanical outcomes.

Experimental Study and Mechanism Analysis on Compression–Shear Behavior of Hydraulic Asphalt Concrete at Different Temperatures

Abstract Hydraulic asphalt concrete (HAC), typically employed as an impermeable structure in embankment dams, is increasingly recognized for its widespread engineering applications. However, investigations of the mechanical performance of HAC under combined compressive–shear stress remain limited, particularly given its temperature sensitivity. Therefore, this study investigates the mechanical behaviors of HAC under combined compressive–shear stress at diverse temperatures and normal compressive stresses. Specifically, the failure modes, stress–strain curves, peak shear stress, and strain of HAC under various temperatures and normal compressive stresses are obtained for analysis. Experimental results demonstrate that the combination of normal compressive stress and temperature induces changes in peak shear stress and correlated shear strain. Increased normal compressive stress results in vertical restriction and the emergence of horizontal cracks, with deformation amplifying at elevated temperatures. All failure modes of HAC under these conditions are absent of spalled fines and debris. It is observed that as the normal compressive stress increases, the peak shear stress progressively increases, whereas an increase in temperature yields a clear decrease in peak shear stress. The shear strength of HAC comprises the cohesion strength of the asphalt matrix and the interfacial adhesion strength between aggregates and asphalt. Finally, three modified compressive–shear failure criteria that exhibit good prediction accuracy are established for HAC at diverse temperatures. This research offers a theoretical reference for the future investigation and engineering application of HAC.

Variable angle of insulated shotcrete under different loading rates and temperature and humidity cycles- shear test and analysis.

The new thermal insulating shotcrete is of great significance for the management of thermal damage in deep mines, and its own strength has a greater impact on the roadway insulation and safe production, so it is very necessary to study the shear strength of the new thermal insulating shotcrete under the influence of the deep hot and humid environment and the stress of mining. For the heat-insulating shotcrete, firstly, we carried out the concrete variable angle shear test under different loading rates, which concluded that the shear rate and peak shear stress showed a trend of increasing and then decreasing; as the angle increases, the different rates have a greater impact on the peak shear stress of the specimen. Secondly, the concrete variable angle shear test was carried out under the temperature and humidity cycle, which revealed that the shear strength of thermal insulated shotcrete increased firstly and then decreased with the increase of temperature at the same number of cycles. Finally, the empirical equations between the cohesive force c, the angle of internal friction ϕ and the number of warm and wet cycles n and the temperature of warm and wet cycles T are fitted with the MATLAB software respectively, and the research results provide technical references for the management of geothermal temperature in deep well projects.

Research on Meso‐Damage Experiment and Simulation in the Anchorage Bonding Interface Between Rock Bolt and Rock Mass

Anchorage failure occurs mostly at the anchorage interface, and the mechanical mechanism of the anchorage interface is the key point and difficulty in the analysis and research of anchorage. In order to study the mechanics and failure mechanism of the anchorage interface, the shear failure characteristics of the anchorage interface and the deformation rule of the anchored rock under different rib spacings were analyzed through the indoor plane anchorage pull‐out test. Reasonable rib spacing can significantly improve the shear strength of the anchored solid. Finite element software ABAQUS was used to create an axisymmetric plane model of rock bolt pull‐out under different rib conditions to simulate the whole process of rock bolt pull‐out and anchorage interface failure. The results show that during the pull‐out process of anchorage rock mass, stress concentration zones occur at rib corners, and peak shear stress moves to the depths of the anchorage section. As the load increases, cracks emerge from the top of the rib and the edge of the rib angle of the rock bolt and propagate to the deep anchorage along the edge of the costal angle, resulting in damage at the rock mass interface. Load–displacement curves of different transverse rib shapes, heights, widths, and spacings indicate that rib changes affect the anchor‐bearing limit. The anchoring failure mode changes from rib wear and spreading slip, rib shear convex body propagation to interfacial crack propagation, and rib causes varying degrees of damage to the surrounding rock mass. Therefore, reasonable rib parameter improvements can enhance anchoring force performance.

Interface Mechanics of Double-Twisted Hexagonal Gabion Mesh with Coarse-Grained Filler Based on Pullout Test.

The interface friction mechanics of reinforcement material with filler is an essential issue for the engineering design of reinforced soil structure. The interface friction mechanics is closely associated with the properties of filler and reinforcement material, which subsequently affects the overall stability. In order to investigate the interface mechanism of a double-twisted hexagonal gabion mesh with a coarse-grained filler derived from a weathered red sandstone, a large laboratory pullout test was carried out. The pullout force-displacement curve was obtained by fully mobilizing the gabion mesh to reach the peak shear stress at the interface between the gabion mesh and the coarse-grained filler. The change of force-displacement characteristics and the distribution of tensile stress in gabion mesh during the pullout process were obtained. A 3D numerical model was established based on the pullout test model, and the model for analyzing the interface characteristic between the gabion mesh and the coarse-grained filler was modeled using the FLAC3D 6.0 platform. The interface characteristics were further analyzed in terms of the displacement of soil, the displacement of reinforcement, and the shear stress of soil. The strength and deformation behaviors of the interface during the entire pullout process were well captured. The pullout force-displacement curve experiences a rapid growth stage, a development transition stage and a yielding stabilization stage. The critical displacement corresponding to peak pullout stress increases with the increase in normal stress. The normal stress determines the magnitude of shear stress at the reinforcement and soil interface, and the displacement distribution of a gabion mesh is not significantly affected by normal stress when the applied normal stress is within a range of 7-20 kPa. The findings are beneficial to engineering design and application of a gabion mesh-reinforced soil structure.

Exploring the shear performance and predictive shear capacity of corroded RC columns utilizing the modified compression-field theory: An investigative study

Corrosion damage substantially weakens the shear strength of reinforced concrete (RC) structures, severely compromising their seismic resistance. Therefore, developing an accurate constitutive model is imperative to investigate the impact of corrosion damage on the shear resistance of RC structures. This study presents a corroded RC shear constitutive model based on the modified compression-field theory (MCFT). To capture the flexural, shear, and slip responses of corroded RC columns accurately, a nonlinear analysis model based on OpenSees is proposed. Comparing the results from four sets of quasi-static tests reveals that the proposed constitutive model and analysis framework can well simulate the seismic performance of corroded RC columns. Based on the comparative analysis, the influence of corrosion-induced damage, reinforcement ratio, and axial load on the shear performance of RC columns is discussed. The investigation findings reveal that high corrosion levels and low reinforcement ratios remarkably weaken the shear strength of RC columns. Additionally, high axial load levels accelerate the rate of post peak shear stress degradation. Moreover, this study proposes a method for estimating the shear strength of corroded RC columns based on the MCFT. The presented approach provides a solid foundation for evaluating the shear and seismic performance of existing RC structures.

Fluid Flow Analysis of Neonatal Dual-Lumen Cannulas for Venovenous Extracorporeal Membrane Oxygenation.

Hemolysis persists as a common and serious problem for neonatal patients on extracorporeal membrane oxygenation (ECMO). Since the cannula within the ECMO circuit is associated with hemolysis-inducing shear stresses, real-world internal fluid flow measurements are urgently needed to understand the mechanism and confirm computational estimates. This study appears to be the first experimental study of fluid flow inside commercial ECMO dual-lumen cannulas (DLCs) and first particle image velocimetry (PIV) visualization inside a complicated medical device. The internal geometries of four different opaque neonatal DLCs, both atrial and bicaval positioning geometries each sized 13 Fr and 16 Fr, were replicated by three-dimensional printing clear lumen scaled-up models, which were integrated in a circuit with appropriate ECMO flow parameters. PIV was then used to visualize two-dimensional fluid flow in a single cross section within the models. An empirical model accounting for shear stress and exposure time was used to compare the maximum expected level of hemolysis through each model. The maximum measured peak shear stress recorded was 16±2 Pa in the top arterial bicaval 13 Fr model. The atrial and 16 Fr cannula models never produced greater single-pass peak shear stress or hemolysis than the bicaval and 13 Fr models, respectively, and no difference was found in hemolysis at two different flow rates. After 5 days of flow, small DLC-induced hemolysis values for a single pass through each cannula were modeled to linearly accumulate and caused the most severe hemolysis in the bicaval 13 Fr DLC. Engineering and clinical solutions to improve cannula safety are proposed.

Investigation on interfacial shear performance of concrete strengthened with bonded steel plate

This study investigated the interfacial shear performance of concrete strengthened with bonded steel plate through tests, fracture energy based theoretical analysis and numerical simulation. Firstly, the interfacial shear bearing capacity of concrete strengthened with bonded steel plate having various lengths was experimentally investigated, and the failure mode and bearing capacity were discussed. Secondly, based on fracture theory, fictitious crack hypothesis, concrete failure criteria and bilinear linear softening shear slip model, the interfacial shear capacity was theoretically derived, including the effective interfacial shear stress transfer length, fracture energy and peak interfacial shear bearing capacity. Moreover, the interfacial shear failure behavior was also numerically simulated, and the interfacial shear stress and normal stress during the whole loading and failure process were discussed. The results confirmed that the numerical simulation using the theoretically derived interfacial fracture energy and peak shear strength could give simulation results in good agreement with experimental results. Also, the calculated interfacial bearing capacity using the theoretical approach showed excellent agreement with the experimental results. Furthermore, the influence of bonding length was also theoretically derived using the numerical parametric simulation results, and a revised interfacial shear bearing capacity considering bonding length was further proposed, which was also in good agreement with both experimental and numerical simulation results.

Study of shear properties and shear model of soil-rock mixture

This study investigates the shear characteristics of soil-rock mixtures, a critical factor influencing slope stability in engineering construction. Soil-rock mixtures, often exhibit poor integrity and can easily soften in water due to geological influences. The YT1200 direct shear drawing friction system was employed to conduct shear tests, analyzing the effect of varying water content and fine particle mass fraction under different normal stresses. Utilizing fractional derivatives, we formulated a fractional derivative shear model. Test results illustrated a softening phenomenon post achieving peak shear stress in the soil-rock mixture. It was found that peak shear stress is directly proportional to the normal stress, and inversely proportional to both water content and fine particle mass fraction. Additionally, the cohesion and internal friction angle decrease according to a power function with increasing water content, and non-linearly decrease with the rise of fine particle mass fraction. The proposed shear model aptly simulates the entire shear failure process of the soil-rock mixture, effectively analyzing the influence of key factors on shear characteristics. These findings contribute to the strength prediction and numerical simulation of soil-rock mixtures, thereby aiding in the design of reinforcement schemes and slope stability analysis.

Ground-motion effects on liquefaction response

This article evaluates the influence of ground-motion characteristics on the liquefaction response of free-field level-ground deposits. Ground motions imposed on liquefiable soils have historically been characterized by the peak ground acceleration (PGA). In simplified procedures for liquefaction evaluation, the use of the ground surface PGA can be justified by the fact that it is closely related to the peak shear stresses developing in the critical zone for liquefaction manifestation, at shallow depths. In nonlinear dynamic analysis (NDA), however, such simplified characterization of the input motion using the bedrock-level PGA can result in large record-to-record variability in the computed response. Record-to-record variability can be substantially reduced by employing more appropriate ground-motion intensity measures (IMs) for specific aspects of the liquefaction response observed in NDA. Among 25 IMs examined in this study, the Modified Acceleration Spectrum Intensity (MASI), defined as the integral of the acceleration spectrum over periods 0.1–1.5 s, is found to be the most efficient IM for the prediction of the pore-pressure response of liquefiable deposits, whereas Velocity Spectrum Intensity (VSI) ranks among the best-performing IMs for response parameters related to ground deformations. Importantly, such “multiple-period spectrum IMs” are shown to perform consistently better than several highly-regarded time-integrated IMs (e.g. Arias intensity, CAV). Conclusions and recommendations are drawn on the basis of a comprehensive series of NDAs involving 180 input motions and 13 deposit models based on characteristic soil profiles from Christchurch.

Experimental study on mechanical properties of recycled aggregate concrete with polypropylene fiber under combined compression‐shear loading

AbstractTo investigate the mechanical properties of polypropylene fiber recycled aggregate concrete (PPFRAC) under compression‐shear, 69 recycled aggregate concrete (RAC) specimens were tested with the parameters of polypropylene (PP) fiber volume content (0, 0.6, 0.9, and 1.2 kg/m3), recycled coarse aggregate (RCA) replacement rate (0%, 30%, 50%, 70%, and 100%), and normal stress (0, 3, and 6 MPa). In the tests, the failure pattern of the specimens was observed, and the effects of the polypropylene fiber content on the direct shear stress, compression‐shear stress, initial shear stiffness, and shear ductility coefficient of the PPFRAC were thoroughly investigated. The results show that as the polypropylene fiber content increases, the direct shear stress of concrete (Natural aggregate concrete and 100% recycled coarse aggregate concrete [100%RCA]) first increases and then decreases gradually. Meanwhile, the best PP fiber content is 0.9 kg/m3 in this study. Furthermore, the compression‐shear stress‐displacement curves of specimens were obtained. The compression‐shear strength under normal stress at 6 MPa is approximately 230% greater than at 0 MPa. However, the peak shear stress of concrete is almost not affected by the replacement rate of RCA. Finally, based on the Mohr circle theory, the compression‐shear calculation model of PPFRAC is verified, and the optimal calculation formula is given.