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In this paper, the bonding of carbon fiber reinforced polymer (CFRP) components by induction heating has been numerically simulated. Being the induction heating bonding phenomenon characterised by an intrinsic multi-physical nature, three different numerical models taking into account, respectively, electromagnetic, thermic and structural aspects, have been introduced and applied to a stiffened composite panel to predict the stringer/skin interface characteristics. The electromagnetic model evaluates the energy loss due to the Joule effect while the thermal model is used to calculate the temperature distribution within the adhesive layer between skin and stringer. Then the structural model predicts the ultimate failure load of the stiffened panel taking into account the degree of cure of the adhesive depending on the temperature distribution at interface between skin and stringers by means of an experimentally determined degradation law. The overall developed numerical methodology has been preliminary validated by comparisons with experimental data in terms of adhesive temperature as a function of time on rectangular composite coupons. Finally, a sensitivity analysis has been performed to evaluate the effects of the geometrical parameters of the stiffened composite panel and process parameters on the degree of cure and then on the mechanical properties of the adhesive at interface between skin and stringers.

Preservation of environment and natural resources has recently attracted researchers to study the use of recycled aggregates from demolished concrete in new concrete structures. This paper presents an experimental study on punching shear behavior of simply supported natural and recycled coarse aggregate concrete slabs. The punching shear behavior of interior slab–column connection in flat plates is tested in “The Reinforced Concrete Laboratory of the Faculty of Engineering, Alexandria University”. Eight two-way slab specimens using two different types of aggregate “natural and recycled” and two aggregate nominal sizes (12.5 and 25 mm) were cast and tested to failure. The slabs were designed such that they would fail in punching shear only. The experimental work was conducted on (6) recycled coarse aggregate concrete (RCAC) slab specimens and (2) natural coarse aggregate concrete (NCAC) slabs. All the slabs were simply supported on four edges and tested under a central patch load. The ACI mix design procedure was adopted to achieve strength of concrete at 28 days of 35 MPa. Four concrete mix proportions were used with (0%, 30%, 60% and 100%) replacement of natural coarse aggregate with recycled coarse aggregate for each aggregate size. The test results showed that the first punch crack load, ultimate punch load, stiffness and energy absorption decrease as the replacement of natural coarse aggregate with recycled coarse aggregate increases. Also as the recycled aggregate size increases the cracking and failure load increases. The measured ultimate failure loads have been compared with code predictions (ECP 203, ACI 318, JSCE code, Euro code 2 and yield line theory). The Euro code – 2 equations gave the best correlation with the experimental results. Keywords: Punching shear, Two-way slab, Recycled coarse aggregate (RCA), Natural coarse aggregates (NCAs), Coarse aggregate sizes

The ultimate strength analysis of laminated composite sandwich plates is presented via ultimate failure load prediction along with modes of failure for laminated composite sandwich plates using mathematical model based on improved higher order shear deformation theory (IHSDT). The proposed IHSDT mathematical model satisfies the inter-laminar shear stress continuity at each layer interface and also ensures zero transverse shear stress conditions at the plate top and bottom. The piecewise parabolic shear stress variation across the thickness of each layer is considered. No shear correction factors are required. The suitable C0 FE formulation of IHSDT model is developed by authors.

To compare biomechanical outcomes of 4 different arthroscopic techniques for fixation of tibial eminence fractures.Twenty-four skeletally mature, fresh-frozen cadaveric knees were divided into 4 comparison groups based on the fixation method: screw fixation (group A), traditional sutures fixation with 2 FiberWire sutures (group B), a modified suture technique with 2 FiberWire sutures that created neckwear knots to firmly trap the fracture fragment (group C), or suture anchors which was based on the suture bridge technique primarily used in the shoulder for repair of rotator cuff tears and greater tuberosity fractures (group D). A tibial eminence fracture was created in each knee for subsequent fixation. After fixation, each knee underwent cyclic loading of 100 N to assess the displacement change after 500 cycles of the fixation construct. Afterward, a single tensile failure test load was performed to assess the ultimate failure load, stiffness, and failure mode for each specimen.All specimens survived cyclic testing and were subsequently loaded to failure. Group C had the highest ultimate failure load (P.05) and group D had the lowest displacement compared with the other 3 groups (P.05). Different failure modes were found among the 4 groups.Suture fixation using the neckwear knots technique provides superior fixation with regard to higher ultimate failure load, and absorbable suture anchor fixation with the suture bridge technique provides less displacement under cyclic loading conditions. Both techniques exhibited superior biomechanical properties compared with traditional screw and suture fixation.The new techniques showed satisfactory biomechanical properties and provided more choice for surgeons in the treatment of tibial eminence fractures.

A self-developed triaxial test method was adopted to characterize mechanical behavior of the asphalt mixture under three-dimensional stress states in this study. The conventional uniaxial tests and triaxial tests were conducted in the laboratory to verify the triaxial test results obtained using the technique developed. It is shown that the three dimensional stress states affect significantly the ultimate failure strength of AC-13 asphalt mixture and the failure modes are mainly represented both for the tensile failure and shear failure. The nonlinear strength criterions, as well as a linear engineering model of asphalt mixture under three-dimensional stress states in σ oct - τ oct space, were established based on the triaxial compressive/tensile tests, the plane tensile and compressive/axial tensile tests. In addition, a new method to carry out the strength design of asphalt pavement under the three-dimensional stress state was given to consider the failure effect of each stress component to the asphalt pavements.

To determine if the depth of anchor insertion affects the biomechanical performance of a 1.5-mm all-suture anchor in glenoid bone.A 1.5-mm all-suture anchor was tested in 8 matched pairs of human cadaver fresh-frozen glenoids. Anchors were inserted at 6 different locations and tested at 3 different depths: 21 mm (preset drilling depth), 17 mm, and 13 mm. Cyclic loading and destructive testing was performed. Displacement after 100 and 200 cycles, along with ultimate failure strength, was determined.After 100 and 200 cycles, anchors placed at 13 and 17 mm had undergone significantly less displacement than those at 21 mm (P.05). No difference was observed in ultimate load to failure between anchors placed at 21 and 17 mm. However, the ultimate load to failure was significantly lower in anchors placed at 13 mm (P.05). There were 5 clinical failures in anchors placed at 21 mm, one at 17 mm, and none at 13 mm.The 1.5-mm all-suture anchor tested in this study has an optimal insertion depth of 17 mm, 4 mm shallower than the preset drill depth. At the optimal insertion depth of 17 mm, it underwent significantly less displacement after cyclic loading without a reduction in the ultimate load to failure.Given the results of this study, the optimal insertion depth for this 1.5-mm all-suture anchor is 17 mm, 4 mm shallower than the preset drill depth.

Composite materials and structures may be characterized at different length scales, ranging from the micro-scale at the fiber–matrix level, meso-scale at the lamina–laminate level, to structural macro-scale. However, uncertainties in material properties and geometric parameters due to manufacturing, defects and assembly processes may occur at various length scales. This paper presents a computational framework for stochastic analysis of composites with consideration of stochastic parameters at micro- and meso-scales. The novelty of the proposed framework is the integration of the spectral stochastic finite element method and asymptotic homogenization method within a finite element technique, which was implemented through $$\hbox {ABAQUS}^{\circledR }$$ . This spectral stochastic homogenization method efficiently predicts the propagation of uncertainties from the constituent to ply levels. The derived probability distributions of effective properties were verified by Monte Carlo simulation. Another novelty is the study of the influence of stochastic parameters at both micro-scale and meso-scale on the failure prediction of composite structures, without assumptions of probabilistic characteristic of ply properties commonly used in a single-scale stochastic analysis. The up-scaled uncertainties combined with other randomness at meso-scale (strength properties and ply orientations) are provided as the input of meso-scale stochastic strength analysis of a quasi-isotropic laminate based on classical lamination theory (CLT) and ply discount. The probability distribution of first-ply failure and ultimate failure loads are obtained and their sensitivity factors with respect to input variations are presented.

Failure due to shear is brittle in nature, and inherent lesser concrete tensile strength is a main contributing factor. During loading before the shear reinforcement could start functioning, cracking in concrete starts. Use of fibers in concrete had proven improved impact on tensile strength of concrete. Active reinforcement role initiates after concrete cracking starts. This paper investigates into the shear behavior of fiber reinforced, pretensioned concrete I-section beam specimens. A total of six beam specimens were cast. Two types of fibers, steel fibers and polypropylene fibers were used in five different proportions. For comparison, one control specimen was also cast without inclusions of fibers in concrete. Concrete mix ratio, prestress force, shear span-to-depth ratio and shear and flexural reinforcement details were kept constant in all specimens. Specimens were subjected to four-point loading to ensure that all specimens fail due to excessive shear force. During tests, deflections and strains were also measured. It was concluded that shear strength of beams was improved using steel fiber reinforced concrete (SFRC) as compared to polypropylene fiber reinforced concrete (PPFRC). SFRC beam containing 0.65% fiber depicted 50.71% improvement in ultimate failure load, 67% improvement in first cracking load and 36% improvement in ultimate deflection as compared to control beam.

In this paper, a probabilistic assessment of supported excavations in spatially varied sands is presented. Random finite element modelling (RFEM) is performed to simulate excavation-induced responses. A procedure for automating the Monte Carlo simulation is developed to facilitate the RFEM. The effects of soil vertical spatial variability on several major geotechnical and structural failure modes, including geotechnical ultimate failure, geotechnical serviceability failure, wall bending failure, wall shear failure, and strut buckling failure, are explicitly investigated. This study demonstrates the importance of addressing the spatial variation of soil properties by considering multiple failure modes for complicated soil-structural interaction problems.

The authors report mechanical strength of nuclear grade silicon carbide fiber reinforced silicon carbide matrix composite (SiCf-SiCm) tubing under several different stress states. The composite tubing was fabricated via a Chemical Vapor Infiltration (CVI) process, and is being evaluated for accident tolerant nuclear fuel cladding. Several experimental techniques were applied including uniaxial tension, elastomer insert burst test, open and closed end hydraulic bladder burst test, and torsion test. These tests provided critical stress and strain values at proportional limit and at ultimate failure points. Full field strain measurements using digital image correlation (DIC) were obtained in order to acquire quantitative information on localized deformation during application of stress. Based on the test results, a failure map was constructed for the SiCf-SiCm composites.

Purpose The purpose of this study was to compare the biomechanical properties among the different double Krackow suture techniques for tendon graft fixation. Methods Thirty porcine flexor profundus tendons were randomly divided into 3 groups of 10 specimens each. Three different double Krackow suture techniques were evaluated, namely, the McKeon's double Krackow (MDK) suture, Wilson's double Krackow (WDK) suture, and Ostrander's modified Krackow (OMK) suture. All suture configurations were completed with a braided nonabsorbable suture. Each suture-tendon construct was pretensioned to 100 N for 3 cycles, cyclically loaded from 50 to 200 N for 200 cycles, and then finally loaded to failure. Elongation after cyclic loading, ultimate load to failure, and the mode of failure were recorded for each specimen. Results There were significant differences in elongation after cyclic loading among the MDK suture (7.9 ± 3.6 mm, 14% ± 6%), WDK suture (11.6 ± 2.2 mm, 22% ± 3%), and OMK suture (9.6 ± 3.3 mm, 17% ± 6%; P = .018). In addition, although the post hoc analysis showed that elongation after cyclic loading in the MDK suture was significantly less than the WDK suture ( P = .004), ultimate failure load and cross-sectional area were not significantly different across the 3 groups. Conclusions In this porcine in vitro biomechanical study, the MDK suture had significantly smaller elongation after cyclic loading than the WDK suture; however, high elongation values may have a potential for risk of clinical laxity. The ultimate failure load was not different across the MDK, WDK, and OMK sutures. Clinical Relevance Smaller elongation during cyclic loading in a suture-tendon construct represents a lower possibility of tendon graft loosening after ligament reconstruction surgery. The double Krackow suture techniques are attractive options for tendon graft fixation in ligament reconstruction, and the MDK suture could possibly be the optimal choice among the double Krackow suture techniques.

This work is carried out to study the influence of double cutouts and stiffener reinforcements on the performance of I-section Carbon Fibre/Epoxy composites beam, including buckling, post-buckling behavior and the ultimate failure. The cantilever I-section beam with two diamond-shaped cutouts in the web and three longitudinal L-shaped stiffeners bonded to one side is subjected to a shear load at free end. Both numerical modelling and Experiment of I-section CFRP beam are performed. In numerical analysis, Tsai-Wu failure criterion is utilized to detect the first-ply-failure load in nonlinear analysis by predicting the load-deflection response. Good agreements are obtained from comparison between the numerical simulations and test results. For the double-hole beam web, the two cutouts show close surface deformation amplitude, which indicates that the stiffeners make the force transformation more effective. Comparing to the numerical result of corresponding beam with single cutout and stiffener reinforcement, the longitudinal stiffeners can not only play a significant role in improving the structural stability (increase about 30%), but also take effects to improve the deformation compatibility of structure. Local buckling happened within the sub-webs partioned by the stiffener and the buckling load is different but close. With post-buckling regime, the two areas show similar deformation characteristic, while the sub-web close to fixed end bears more shear load than the sub-web close to loading end with the increase of normal deformation of structure. The catastrophic failure load is approximate 75.6% higher comparing to buckling load. Results illustrate that the tensile fracture of the fiber is the immediate cause of the ultimate failure of the structure.

This paper describes an experimental investigation into the seismic response of concentrically braced steel frames (CBFs). Twelve shake table tests were performed on full-scale single storey frames, each containing a pair of identical brace members. The experimental programme examined the behaviour of brace members with four different square and rectangular hollow cross-sections and a range of gusset plate connection details. The aim of the experimental study was to determine the influence of brace and gusset plate properties on CBF response from serviceability to ultimate limit states, including collapse. Consequently, all test frames were subjected to three levels of seismic excitation: (i) low-level excitation to examine elastic frame response, (ii) medium-level excitation to examine brace buckling and yielding effects, and (iii) high-level excitation to induce brace fracture. A detailed set of data on the seismic response of CBFs with realistic brace members and connections were obtained from the tests. The experiments were conducted under representative dynamic response conditions as opposed to the conventional idealised quasi-static loading procedures employed in previous experimental investigations of CBF behaviour. The results faithfully capture the behaviour of brace-gusset plate test specimens with different non-dimensional brace slenderness, brace cross-section slenderness, connection types and gusset plate detailing. The response variables measured in each test included the shaking table and frame accelerations and displacements, brace elongation and axial force, and brace member and gusset plate strains. The experimental observations include elastic frame vibration properties, acceleration and drift demands, ultimate failure modes and ductility capacity. The brace-gusset plate test specimens remained elastic at low-level excitations, brace buckling and yielding occurred in all medium-level excitation tests, while specimens exhibited brace fracture under high-level excitation. Fracture did not occur in the gusset plate connections irrespective of whether these were designed using a conventional design method with a Standard Linear Clearance (SLC), or a balanced design with an Elliptical Clearance (EC). However, the balanced design approach showed more uniform distribution of plastic strains and led to higher brace ductility capacities when compared to the conventional design method. Based on the test results, available methods for predicting the ductility of bracing members are compared and assessed, and a number of considerations for design are highlighted and discussed.

A universal method is established to research the various possible damage modes of adhesive bond of laminated composites with or without z-pin reinforcements under tensile loads through numerical simulation. A Continuum Damage Mechanic model based on Hashin damage criterion as a user-defined subroutine is developed to simulate the damage of laminates and Z-pins. The Cohesive Zone Model is used to simulate the damage of adhesive damage, interlayer delamination, and Z-pin slipping-out phenomenon. The numerical simulation method is validated for simulating the various damage modes of the usual composite joints through comparing the simulated results and experiments. The research shows that different ply sequences induce different damage modes and ultimate failure loads of composite joints. The ultimate failure load of joint under tension is not affected obviously whether the joints are reinforced with or without z-pins. The reason is that the damage initiation usually locates at the two sides of adhesive zone and z-pins do not react on the reinforcement under tensile load of joint.

The crack initiation, growth, wrapping and coalescence of two 3D pre-existing cross-embedded flaws in PMMA specimens under uniaxial compression are investigated. The stress–strain curves of PMMA specimens with 3D cross-embedded flaws are obtained. The tested PMMA specimens exhibit dominant elastic deformation and eventual brittle failure. The experimental results show that four modes of crack initiation and five modes of crack coalescence are observed. The initiations of oblique secondary crack and anti-wing crack in 3D cracking behaviors are first reported as well as the coalescence of anti-wing cracks. Moreover, two types of crack wrapping are found. Substantial wrapping of petal cracks, which includes open and closed modes of wrapping, appears to be the major difference between 2D and 3D cracking behaviors of pre-existing flaws, which are also first reported. Petal crack wraps symmetrically from either the propagated wing cracks or the coalesced wing cracks. Besides, only limited growth of petal cracks is observed, and ultimate failure of specimens is induced by the further growth of the propagated wing crack. The fracture mechanism of the tested PMMA specimens is finally revealed. In addition, the initiation stress and the peak stress versus the geometry of two 3D pre-existing cross-embedded flaws are also investigated in detail.

The study pertains to finite element analysis of two interfering strip footings (symmetrical and asymmetrical with respect to footing size) resting on the surface of a nonlinearly elastic soil (dense/loose sand) medium obeying Duncan and Chang’s hyperbolic constitutive relationship. Predicted pressure–settlement behavior, bearing pressure and settlement characteristics of the interfering footings are then compared with the same for isolated footing, expressing the interference effects in terms of non-dimensional interaction factors. It is found that the characteristic behavior of an isolated footing is greatly influenced due to interference of a nearby footing. Studies have shown that for dense sand, interference affects the response of isolated footing much more compared to loose sand and for asymmetrical footings at very close spacing, the effect is more pronounced for footing with small size. The variation of pressure-interaction factors measured in working/allowable range is found to be similar to that measured at the ultimate failure, but on the contrary, the settlement-interaction factors are found to be different.

The response of thin slabs of Slurry-Infiltrated Fibrous Concrete (SIFCON) with and without reinforcement under low velocity impacts is explored via drop-hammer impact experiments. For comparison purpose, plain cement concrete (PCC) and reinforced cement concrete (RCC) slabs were also cast and tested. To produce SIFCON slabs made with binary cementitious materials, the pre-determined concrete mixtures were designed with 15% of silica fume, 30% of blast furnace as a partial substitute of cement along with a constant 10% of hooked end steel fibres by volume fraction. The replication of a low-velocity impact on slab was achieved by dropping a steel ball (weighing 4.5 kg), with fall height of 457 mm, via the utilization of a self-fabricated drop-hammer impact test device. The parameters like first crack and ultimate failure energy absorption capacity, ultimate crack resistance, crack resistance ratio, ductility indices, and failure pattern were examined. The test results reported that the incorporation of binary blends of silica fume and slag in SIFCON matrix shows better performance in terms of strength and durability characteristics.

The evaluation of the static interaction of closely spaced footings and its influence in the overall bearing capacity and settlement on sand and clay soils is addressed in this review. The work is accomplished through a comprehensive look into all relevant literature regarding the interaction of sallow foundations, assessments are made, and conclusions are drawn which will ultimately be relevant to future endeavors associated with the design and the evaluation of closely spaced shallow foundations in terms of determining the optimal spacing between footings, enhancing bearing capacity, and controlling deformation. Furthermore, the work is divided to three major approaches: theoretical studies, experimental or field tests, and numerical analysis. Each have been discussed thoroughly in details, with indicating the shortcomings of previous studies and where each approach has reached. The result of this review has showed that nearly all previous research studies explored the effect of the interaction of closely spaced shallow foundations on the bearing capacity at the ultimate failure compared to the settlement behavior which is for some reason not addressed profoundly,even though it is more critical than bearing capacity. Additionally, current regulations and codes have not devoted a major effort toward addressing the influence of closely spaced shallow foundations appropriately, especially today,where the limitation of a site and the placing of footings close together in order to accommodate structural details are becoming a more common issue.

A reliability-based design (RBD) method for rigid pipes installed using induced trench with tire-derived aggregates (TDA) inclusion is introduced in this study. The design process is to find an optimal set of the TDA inclusion dimension (i.e., width B and thickness t) that satisfies the 0.01-inch crack serviceability limit state and ultimate failure limit state requirements of the pipe, and achieves a target probability of failure or target reliability index using Monte Carlo simulation. The uncertainty and load-dependent compressibility of TDA inclusion are considered. Two design examples are provided, which show that the serviceability limit state design controls the finial design of induced trench installation (ITI) pipes. Increasing the thickness of TDA inclusion is helpful to improve reliability of the pipes, while expanding the width of TDA inclusion might increase probability of failure. The sensitivity and flexibility of using different target reliabilities, parameter uncertainties and calculation models in the proposed RBD method are examined. The results show the importance of considering the variability and load-dependent compressibility of TDA in the proposed RBD method for the design of ITI pipes with TDA inclusions.

In the present study, an experimental program was executed to investigate the performance of a composite structural system under direct compression load. The system consists of a uPVC tube as the mold for pouring the fresh concrete and a confining device for structural concrete. Three thicknesses of plastic tubes (4, 5, 7 mm) were investigated using four sets of three stub columns. Rice husk ash (RHA) was used as a cement replacement material to improve the strength and other mechanical properties of concrete core with target compressive strengths of 30 MPa for sets one and two and 60 MPa for sets three and four, respectively. The load capacity of uPVC strengthened blended concrete improved, and the ultimate failure is ductile due to the elongation capacity of the polymeric tube. To examine the post-peak behavior of the confining device at near-collapse conditions, two stub columns were subjected to five repeated loading that almost produced full collapse conditions in each cycle of loading after the first cycle. The tubes effectively dissipated energy by plastic yielding, which could be considered a partial progressive failure. Several analytical expressions have been proposed, in total twenty-four, for predicting the strength capacity of the composite system. However, most of these empirical expressions have been derived based on limited experimental tests. Therefore, to assess the performance of the existing strength models in predicting the capacity of PVC-confined concrete (PCC) and uPVC-confined concrete (uPCC); a comprehensive database of 389 test results was assembled from the published literature that covers the studies published in the period 1979–2021 combined with the twelve data from the present study. To account for the height/diameter ratio (H/D), three cases were examined; case one (3 ≤ H/D >3), case two (H/D ≤ 3), and case three (H/D >3). Based on the compiled database, two strength-based confinement models were proposed for circular concrete specimens confined externally with PVC or uPVC tube. The two models include several parameters that influence the properties of the concrete core and the confining device. The proposed models are the most accurate among all the models yielding lower values of absolute average error for the three cases examined.

The frame-truss composite wall is a wall assembled by a certain number of resistance unit composed of outer frame and internal diagonal struts . As the primary energy dissipation unit of the system, the resistance unit should be studied in the perspective of internal force analysis. When the internal force of resistance unit is analyzed, the outer frame and the internal diagonal struts are regarded as composite members of reinforced concrete. According to the characteristics of resistance unit, the outer frame is regarded as a rigid frame and the internal diagonal struts are treated as struts hinging with the rigid frame and mainly subjected to axial force . So the simplified model is formed and it can be regarded as seven-degree statically indeterminate structure in mechanics. The internal forces of outer frame and internal diagonal struts corresponding to the constraint forces of simplified model can be calculated by solving the statically indeterminate problem. The ABAQUS model of resistance unit is established to simulated the performance so that the internal force can also be obtained in another way. The constrain force of simplified model and the internal force of ABAQUS model are comparatively analyzed and the results show a feasibility of simplified model. The phenomenon of cracks on diagonal struts and ultimate failure state of resistance unit are compared with the stress cloud of ABAQUS model to explains the reasonability of simplified model. The applicability of ABAQUS model is further stated by comparing the stress of longitudinal rebar on the most dangerous section between the simplified model and ABAQUS model for the resistance unit. This simplified model can provide a method to analyze the internal force of the resistance unit under external load, which also lays a foundation for the subsequent researches.

Geopolymer concrete (GC) is a substantial sort that is created by utilizing metakaolin, ground granulated blast furnace slag (GGBS), silica fumes, fly ash, and other cementitious materials as binding ingredients. The current study concentrated on the structural behavior of the ferrocement geopolymer HSC-columns subjected to axial loading and produced using rice straw ash (RSA). The major goal of this research was to use the unique features of the ferrocement idea to manufacture members that function as columns bearing members. As they are more cost-effective and lower in weight, these designed elements can replace traditional RC members. The study also intended to reduce the cost of producing new parts by utilizing low-cost materials such as light weight expanded and welded wire meshes, polyethylene mesh (Tensar), and fiber glass mesh. For this purpose, an experimental plan was conducted and a finite element prototype with ANSYS2019-R1 was implemented. Nine geopolymer ferrocement columns of dimensions of 150 mm × 150 mm × 1600 mm with different volume-fraction and layers as well as a number of metallic and nonmetallic meshes were examined under axial compression loading until failure. The performance of the geopolymer columns was examined with consideration to the mid-span deflection, ultimate failure load, first crack load with various phases of loading, the cracking patterns, energy absorption and ductility index. Expanded or welded ferrocement geopolymer columns showed greater ultimate failure loads than the control column. Additionally, using expanded or welded columns had a considerable effect on ultimate failure loads, where the welded wire mesh exhibited almost 28.10% compared with the expanded wire mesh. Columns reinforced with one-layer of nonmetallic Tensar-mesh obtained a higher ultimate failure load than all tested columns without concrete cover spalling. The analytical and experimental results were in good agreement. The results displayed an accepted performance of the ferrocement geopolymer HSC-columns.

Purpose Finger avulsion injuries account for 5% of upper extremity injuries requiring evaluation in an emergency room. They are devastating injuries that require microvascular reconstruction or amputation. As public awareness rises, there is a growing market for silicone rings, with limited data on their ability to prevent ring avulsion injuries. Methods Five cadaver forearms were attached to a custom fixture, allowing for ring avulsion simulations. Specifically designed silicone or metal rings of varying sizes (#4–#11) were assigned to one of five fingers on each forearm, based on fit. The contralateral corresponding finger was tested using a ring of the same size in the other material. A preload of 2 N was applied to each ring, and ultimate failure force was determined by applying an upward force at a loading rate of 500 mm/sec until failure. Additionally, a fifth cadaver forearm was used to determine the ultimate failure force of silicone rings in a clenched fist position. Results The average ultimate failure force for silicone rings of all sizes was 53.0 N, compared to 495.2 N for metal rings of all sizes. The average ultimate failure force of silicone rings in the clenched fist position was increased across rings of all sizes, with an average of 99.9 N. There were no degloving injuries in the silicone ring avulsion group. Conclusions Biomechanically, silicone rings have a significantly lower failure force than metal rings and may help prevent ring avulsion injuries. Clinical relevance The use of silicone rings should be encouraged in professions where ring avulsion injuries are more likely, such as heavy labor.

In order to study tensile behavior and failure mechanism of the integrated composite joints of the skin, the longeron and the frame in fuselage structure, the adhesively bonded (joint A) and the mechanically fastened (joint B) integrated composite joints were designed and manufactured. Tensile tests were performed for both joints. The strain versus load curves and the load versus displacement curves were measured, analyzed and compared. It is shown that the first drop load and the ultimate failure load of joint A are 120.82kN and 168.11kN, respectively. While the first drop load and the ultimate failure load of joint B are 41.05kN and 68.22kN. The finite element models for both joints had been established to simulate and analyze failure mechanisms, interlaminar damage behaviors and effects of design parameters on mechanical properties. The dominant failure modes are delamination and interface debonding, which caused by the weak interlaminar strength between joint components. Damage initiation of joint A occurs at the corner bend region of the corner-stiffened laminate around the filler, and then propagates along the radius bend region of the corner-stiffened laminate, and finally leads to the interface debonding and the delamination in the interface of both stiffeners of joints. Damage initiation and propagation occurred at the center of the skin and the L-stiffened laminates of joint A. While for joint B, damage initiation and propagation of the corner-stiffened laminates and the L-stiffened laminates were changed because of the holes. The strength of joint A is two times higher than that of joint B, whether the stacking sequence and the thickness changes or not.

This study proposed an innovative underground support system with I-shaped sections that use steel corrugated webs. The in-plane global buckling behavior of the proposed system was investigated through comprehensive experimental, numerical, and analytical analyses. An experimental test was carried out against a scaled specimen of the proposed support for U-shaped mining roadways when subjected to three concentrated loads. The global asymmetric buckling was identified as the ultimate failure mode. A finite element (FE) model was constructed and verified by comparing its analysis results with the experimental outcomes. Finite element analyses (FEA) first proved that both the stiffness and force capacity of the support with corrugated webs could be much increased when compared with the I-shaped steel that uses flat webs under the same steel consumption. The elastic and elastoplastic buckling analyses from the FEA further indicated that the web height and flange thickness were the influential parameters, from which a closed-form formula was developed to predict the elastic buckling load as a function of the slenderness ratio. Analysis results have shown that the support system will inevitably fail through antisymmetric instability when the slenderness ratio is large, yet the system was not very sensitive to initial imperfections. A design formula for the in-plane compression-bending capacity was derived for the proposed support system by synthesizing and modifying existing relevant design equations. The proposed innovative support system, together with the associated experimental testing, FEA, elastic buckling load formula, and design equation, paves the way to promote its real-world applications as tunnel supports to deal with harsh geological conditions (e.g., soft rocks).

Background: Multiple techniques for fixing a graft to the patella in medial patellofemoral ligament (MPFL) reconstruction have been described; however, no single technique has been shown to be superior to another. Purpose/Hypothesis: The purpose of this study was to compare the biomechanical performance of 2 different patellar fixation techniques: suture anchor (SA) and transosseous suture (TS) fixation. The hypothesis was that there would be no significant differences between the groups in ultimate failure load, stiffness, or elongation. Study Design: Controlled laboratory study. Methods: In this study, a new TS technique was biomechanically compared with the SA technique for MPFL reconstruction using 24 fresh-frozen mature porcine patellae and porcine flexor profundus tendons. The specimens were randomized into 2 groups undergoing MPFL reconstruction using either the SA technique or the TS technique (n = 12 per group). Fixation with TS was completed using 3 No. 2 UltraBraid sutures and three 2-mm transosseous tunnels. SA reconstruction was completed using 2 parallel 3.5-mm titanium SAs with 2 No. 2 UltraBraid sutures. We preconditioned each graft using a force between 5 and 20 N before cyclic loading. Then, the specimens were biomechanically tested (1000 cycles; 5-100 N; 1 Hz) and loaded under tension at 200 mm/min until failure. The ultimate failure load, stiffness, elongation, and failure mode were recorded for each specimen. The Shapiro-Wilk test and independent t tests were used to assess the data. Results: The TS technique resulted in a significantly higher mean failure load than did the SA technique (496.18 ± 93.15 vs 399.43 ± 105.35 N; P = .03). The TS technique resulted in less stiffness than did the SA technique (55.42 ± 7.92 vs 72.11 ± 10.64 N/mm; P < .01). There was no significant difference between the groups in elongation. None of the graft fixation/patellar complexes failed during cyclic testing in either group. During the load-to-failure test, the most common mode of failure in the SA group was an anchor being pulled out of the bone, whereas that in the TS group was rupture of the suture material. Conclusion: MPFL reconstruction with 3 TSs provided a higher load to failure than did the commonly used fixation method involving SAs.

This paper evaluates the structural behaviour of precast reinforced concrete (RC) beam-columns connected with novel ribbed headed bars, and compares with conventional anchorage system of development length and partial development length. Additionally, the effect of encasement with expa-mesh and varying spacing of lateral ties in precast RC column is also investigated. Precast RC beam-column joints were subjected to the displacement controlled quasi-static reversed cyclic loading on the beam end and constant axial load on the column. Structural behaviour was assessed with regards to damage pattern, cyclic load capacity, stiffness degradation , deformation characteristics and energy dissipation ; and performance assessment carried out in accordance with ACI 374.1–05. Most of the specimens experienced crack at the interface of beam-column joint at yield limit. Ultimate failure was beam rebar rupture along with separation of beam and column, thus forming plastic hinge at the joint, rather than in the beam element. Both headed bar and conventional specimens surpassed their nominal moment strength and design shear force, thus exhibiting satisfactory performance. On the other hand, specimens with partial development length attained their nominal moment strength but failed to reach joint shear. The strength parameters of headed bar specimens were well comparable to that of conventionally detailed specimens and satisfied the acceptance criteria of ACI 374.1–05, which can be considered as a benchmark to adopt the proposed ribbed headed bar system of anchorage for precast RC beam-column joints in light of its certain advantages over conventional anchorage system.

The mechanical failure of three-dimensional (3D) 4-step braided SiCf /SiC composites, processed by precursor infiltration pyrolysis , has been studied under flexural loading to investigate the condition at failure. The investigation integrated the advantages of continuous data acquisition by optical imaging and 3D reconstruction of internal structure in X-CT imaging, for in situ investigation of microstructure-related failure mechanisms. Optical imaging with digital image correlation acquired the surface displacements. X-ray computed tomographs, obtained in situ, were analysed by digital volume correlation to measure the 3D displacement fields. Image subtraction, informed by the 3D displacements, was used to detect and visualize crack development. Curvature measurement, via the displacement fields, monitored the change in effective flexural modulus . The observed failure modes included matrix cracking , inter- and intra-bundle debonding and fibre breakage . Tensile cracks were arrested by the heterogeneous microstructure, and the ultimate failure under flexural loading was due to multiple cracking in compression.

The seismic behavior of an embedded concrete-filled steel tubes (CFST) precast column-to-cap beam socket connection of a practical engineering project was investigated through 1:3-scale quasi-static tests. The precast column and cap beam was integrated by ultrahigh-performance concrete (UHPC) grouting to improve the interface bonding behavior and lateral constraint. The influences of embedment depth, socket forming method, and column section size on the cyclic response of the structure were evaluated. The experimental results revealed that when the concrete-filled steel tube (CFST) embedded depth is 1.0 times tube diameter, the specimens can obtain good strength and hysteresis performance. The socket hole formed by a steel pile can further promote the hysteresis performance of the cap beam-column joint, and the ultimate failure of the joint is the fracture of the column longitudinal rebar. A model for evaluating the moment capacity of the CFST socket connection was proposed and verified by the test results, which can be used in the preliminary design the proposed connection.

Fissures are generally existing in engineering rock mass, and cracking pattern observed in specimens with multiple fissures is analogous to the pattern obtained in specimens with two fissures, whereas the cracking coalescence of real rock specimen under triaxial compression have rarely been investigated. Therefore, thirty fissured rectangular specimens containing two non-coplanar fissures with different ligament angles were prepared to perform triaxial compression in this work, and the stress-strain curves, strength and deformation parameters, ultimate failure modes and Acoustic Emission (AE) characteristic were investigated. The experimental results indicate that pre-existing fissures have a significant effect on the stress-strain curves, more stress drops were observed before and after the peak strength, whereas confining pressure cannot reduce stress-drop. Cohesion (C) of peak strength and damage threshold has different trend with ligament angle (β), and the C of the peak strength is larger than that of the damage threshold. Pre-existing fissures have more effect on damage threshold than peak strength; cracks are easier to initiate in fissured specimen. It is easier to coalesce when ligament angle is parallel to the maximum principal stress, and cracks are easier to expand in width direction than that in thickness direction. The coalescence of the two non-coplanar fissures is classified as five typical modes, and the CT result shows that crack distribution in depth direction is similar. Crack classification by AE parameter and k-mean method can reflect the cracking process in a certain extent. It is more drastic when shear crack initiates, and tensile crack propagates in a stable way.

Background: The present in vitro study aimed to investigate the fatigue performance of different dental fixtures in two different emergence profiles. Biological failures are frequently reported because the problem canonly be solved by replacing a failing implant with a new one. Clinicians addressed minor mechanical failures, such as bending, loosening or the fracture of screws, abutment, or the entire prosthesis, by simply replacing or fixing them. Methods: Transmucosal and submerged bone-level dental implants underwent fatigue strength tests (statical and dynamical performance) by a standardized test: UNI EN ISO 14801:2016. Two types of emergence profiles (Premium sub-crestal straight implant with a cylindrical-shaped coronal emergence or Prama one-piece cylindrical-shape implant with transmucosal convergent neck and hyperbolic geometry) were tested, and dynamic fatigue were run to failure. Data was analyzed by a suitable statistical tool. Results: The Wöhler curve of 0.38 cm Premium group c2, appeared to be significantly different from that of the 0.38 cm Prama group c3 (nonparametric one-way ANOVA χ2= 6, degree of freedom = 1, probability = 0.0043) but not from that of the 0.33 cm Premium group c1 (nonparametric one-way ANOVA χ2 = 0.62, probability = 0.4328). Fatigue performance of configuration 2 was one and a half times better than that of configuration 3. Group c3 had a better ultimate failure load (421.6 ± 12.5 N) than the other two settings i.e., c1 (324.5 ± 5.5 N) and c2 (396.3 ± 5.6) reaching almost a nonsignificant level. Conclusions: It was observed that a transmucosal implant design could provide the highest resistance to static fracture. On the other hand, an equicrestal implant design could increase dynamic endurance.

Cold-formed steel (CFS) unlipped channel sections are commonly used as bearers in floor systems while rectangular hollow sections (RHS) are used as joists. The transverse loads from the joists do not pass through the shear centre of channel bearers due to different joist to bearer and bearer to column connections. Hence, the channel bearers are subjected to torsion in addition to concentrated loads and bending. This study investigated the effects of two joist to bearer (bolted/welded) connections, two bearer to column (cap plate/angle cleat) connections and fly braces on the structural behaviour of channel bearers. Eight full-scale tests were performed using simplified floor arrangements, made of two unlipped channel bearers with eight and six RHS joists located at 450 mm spacing. Suitable finite element models of tested channel bearers including their connections were developed and validated in terms of ultimate failure moment, failure mode and deflections. A parametric study was then performed using the validated finite element models. The effects of bolted/welded joist to bearer connections and cap plate/angle cleat bearer to column connections on the behaviour of channel bearers were determined and discussed based on the experimental and numerical results. Suitable recommendations were then made to the design methods based on the observed failure modes, and the most suitable combination of connections for the CFS floor systems investigated in this study.

This paper presents numerical analysis on fracture failure of steel beam-to-column connections subjected to low-cyclic fatigue loading. A numerical approach is developed and implemented in the finite element program using the concept of lumped damage mechanics to estimate the extent of fracture damages until complete rupture failure occurred in beam and column hinges. In this framework, a damage variable is introduced for each end of beam elements, and can be linked to the extension of the fatigue fracture in the real structural components. The damage evolution law is based on the Manson–Coffin law and a new crack-driving variable to emulate the state of ultimate failure. The model also describes crack closure effects due to weld access hole at the edge of beam connected to column surface. The analytical model is validated using component tests of steel beam-column connections with weld access hole subjected to cyclic loadings with constant and variable amplitudes. Limitations of the model are also discussed for wider applications on the failure simulation of steel frame systems subjected to seismic loading.

Full-scale bearing accelerated life test experiment is an effective way to achieve the demand of modern aero-engine bearing. However, its premise is how to determine the boundary reasonably. In this study, the factors leading bearing abnormal failure are presented by the fault tree analysis. Then, the boundary conditions of aero-engine bearing are analysed by the quasi-dynamic method. The relationship between status parameters associated with failure modes (such as lubricating oil film thickness, etc.) and working parameters (such as rotation speed, external load) is discussed. It revealed the interrelation between practical working condition and status parameters in graphical form. The analysis provided theoretical bases for the choice of working parameters and the ultimate failure judgment in the accelerated life test.

The worldwide demand for new concrete buildings is increasing at a rapid pace to keep up with urban development. On the other hand, plastic waste of vehicle causes serious health and environmental problems all over the world. The reuse of wastes is important from different points of view. It helps to save and sustain resources that are not replenished. As a possible solution to the problem of plastic waste of vehicle, an experimental study was conducted to examine the potential of using it as sand replacement in the concrete buildings. This paper examines ultimate failure resistance of concrete with 5%, 10% and 15% of sand replacements by waste plastic of vehicles under impact. For each amount, six cubes of 100 mm × 100 mm × 100 mm were subjected to 4.5 kg hammer from 480 mm height. The number of blows of the hammer required to induce the ultimate failure of the cubes were recorded. The results are presented in terms of impact energy required for the ultimate failure. The concrete mixtures exhibited ability to absorb a large amount of impact energy. The plastic waste of vehicle increased the impact energy for the ultimate failure with sand replacement by plastic waste of vehicle.

Rock response to confining pressure and strain rate can change dramatically from very brittle to ductile. Capturing this transition is crucial for a correct prediction of rock mass failure due to blasting, explosion or drilling in mining. In this work, a new constitutive model that accounts for the effects of both confining pressure and strain rate on the nominal strength and post peak behaviour is proposed for dry intact rocks and other similar geological materials. The key features of the proposed constitutive model are the employment of a single loading function that evolves from initial yielding to ultimate failure during damaging and the rate-dependent enhancement so that the strain rate effects can be faithfully described at different confining pressures. The model can adequately capture both the brittle and ductile responses as well as the brittle-ductile transition as a result of both strain rate and confining pressure.

A grouted connection is a type of structural composite connection member produced from two different-sized steel tubes and a grout annulus between them. The grouted connection has been widely used in offshore oil and gas platforms and wind turbine structures by simply grouting between the pile and sleeves. In general, the axial compression strength of the connection is known to be affected by the grout strength, shear-key spacing and radial stiffness parameters of the composite section. In this study, concentric and eccentric loading tests were performed to investigate the interfacial shear behavior of the high-strength grouted connections according to the shear-key spacings. The interface shear behaviors, focusing on the strength, failure mode, and strain of the grout and steel tubes, were evaluated by tests and finite element (FE) analysis. The test results showed that the primary strength of the connection was mainly affected by the grout strength, whereas the ultimate strength was affected by the yield strength of the sleeves and the friction coefficient between the steel tubes and grout. It was also concluded that the test results on the high-strength grouted connections were similar to those of previous studies on normal-strength grouted connections, and the eccentric loading did not reduce the axial capacity of the connection. Although the ultimate failure modes of the connections could not be considered in the current design equations, they may contribute to the safe design of high-strength grouted connections.

The fire stability of carbon fiber reinforced polymer (CFRP) shell structures was investigated using an intermediate-scale test setup. The shell specimens are representative of typical load-bearing CFRPs in modern civil aviation. The CFRP shell specimens were exposed to a fully developed fire with direct flame impingement to one side at a heat flux of 182 kW/m 2 . Specimens were simultaneously loaded with constant compressive force equal to 40% of the ultimate failure load. CFRP shells and four different fire retarding configurations, using integrated protective layers, were investigated. Unprotected CFRP specimens failed after just 27 s. Specimens with integrated protective layers with low heat conductivity and high burn-through resistance showed the most promising results. An integrated titanium foil decelerated the decomposition of the epoxy matrix and increased the time to failure by 68% compared to the unprotected CFRP shell.

peer-reviewed A novel concept for joining materials is presented which employs adhesive joints with interlocking bond-surface morphology formed on the surfaces of male and female adherends that mechanically interlock in shear when brought together. In the present work, miniature, single-lap joint specimens with a single truncated square pyramid interlocking profile, centred in the bond area, are investigated. The performance of the concept is assessed through finite element analysis (FEA) by incorporating yield criteria representing plasticity in the adherends and a cohesive zone model to represent damage in the adhesive layer. This allows for effective simulation of the joint response until ultimate failure and thus, full assessment of the concept's performance. Various interlocking geometries are explored and refined through an adaptive surrogate modelling design optimisation procedure coupled with FEA. The results indicated that significant improvements in work to failure, of up to 86.5%, can be achieved through the more progressive failure behaviour observed compared to that of a traditional adhesively bonded joint. Improvements in the joint's ultimate failure load can also be achieved with a relatively ductile adhesive system. ACCEPTED peer-reviewed

The response of reinforced concrete (RC) shear wall as a lateral resisting member has been studied extensively, but it still demands a general practical model that identifies the envelope within which load–drift paths occur during cyclic loading. Such a broad model is vital to ensure adequate lateral strength to resist reversal loadings imposed on these walls during earthquake events and ductility to measure inelastic deformation capabilities. A new model to define the backbone curve is developed in this paper for squat, intermediate, and slender flanged and non-flanged RC walls. The most common failure modes observed in the field and laboratory experiments are investigated and incorporated in the proposed model to estimate the response of these walls from elastic range until ultimate failure. The main parameters controlling the estimation of drifts that features the backbone curve thresholds are presented in this paper. The results of proposed model are compared with the outcomes of 117 specimens experimentally tested by other researchers. Also, the results are compared with Federal Emergency Management Agency (FEMA) 356, the updated American Society of Civil Engineers (ASCE)/Structural Engineering Institute (SEI) 41, and Eurocode (EC8 and EC2) provisions which reveal that only one general model, proposed in this paper, can capture the response of RC structural walls with an aspect ratio ranging from 0.35 to 2.5 and an axial load ratio from 0 to 0.4 with good agreement with experimental outcomes.

The paper presents a systematic numerical simulation of rock-like specimen containing two pre-existing unparallel flaws under uniaxial compression. The strength and deformation properties and crack evolution process of pre-flawed specimen are compared with the corresponding laboratory experimental results. The numerically simulated results, such as the axial stress–strain curve, the strength and deformation parameters, the ultimate failure mode and the crack coalescence process, were all in a good agreement with the experimental results, suggesting the validity of the calibrated micro mechanical parameters. The stress field during the crack coalescence process was analysed to reveal the mechanism of crack evolution. When the flaw angle was smaller or equal to 30°, the tensile stress concentration was distributed at the middle surface of pre-flaw. As the flaw angle increased, the tensile stress concentration was diverted from middle surface to the tips of pre-flaw. Finally, two typical displacement...

The shear strength of heavily overconsolidated, stiff-to-hard plastic clays is crucial to their stability and also influential on the ground movements they develop in many geotechnical engineering applications. This paper considers the shear strength anisotropy of the London, Gault, Kimmeridge and Oxford clays through advanced hollow cylinder experiments on multiple high-quality samples taken at similar depths from inland sites where the geotechnical profiles have been established by comprehensive laboratory and in situ testing. Suites of undrained tests are reported, which loaded specimens from their in situ stress states to reach ultimate failure at pre-defined final major principal stress axis orientations defined in the vertical plane, while also controlling or monitoring the intermediate principal stress ratio, b. Both stress path and simple shear tests were undertaken with the hollow cylinder apparatus, which offers key advantages over conventional simple shear equipment. The interpretation reveals patterns of marked shear strength anisotropy that impact significantly on numerous geotechnical engineering applications.

The main objective of this paper is to investigate the effect of intra-ply hybrid patches based on glass and Kevlar woven fabrics on the local bending response of adhesive bonded external patch repairs in damaged glass/epoxy composite laminates. In intra ply hybrid patches glass and Kevlar fibre reinforcements are combined in the same layer. The intention, in using these hybrid patches, is to combine the excellent mechanical properties of glass fiber as a brittle reinforcement with the superior high elongation to failure property of Kevlar fiber as a ductile reinforcement. Five different kinds of plain weave woven fabrics with different ratios between glass and Kevlar fibers (100/0, 75/25, 50/50, 25/75 and 0/100) were used as the external patches. The undamaged virgin specimens were taken as a reference for the comparison of residual mechanical properties. Multiple quasi-static indentation tests were carried out on repaired glass/epoxy specimens, and their ultimate indentation load, stiffness and permanent deformation were estimated. Failure mechanisms of repaired glass/epoxy specimens under indentation loads were investigated using online Acoustic Emission (AE) monitoring technique. The indentation loads required for the occurrence of various failure modes were measured to illustrate the chronology of progression of different damage modes with increasing load and the kinetics of the various damage modes individually defined in real time. The use of different hybrid patches had a significant effect on the local bending response of the repaired glass/epoxy specimens. In practice, specimens repaired with patches including equal volume fraction of glass and Kevlar fibers presented a more favorable indentation response than virgin ones and other repaired specimens by exhibiting balanced mechanical properties (i.e., high deflection to ultimate failure associated with superior patch-parent laminate bond strength).

In this article, behavior of ten beam specimens, including five hexagonal castellated beams and five typical wide flange beams, in the post-tensioned semi-rigid beam-to-column steel connections of moment-resisting frames has been analyzed theoretically and numerically by well-known finite element software (ABAQUS 6.11-PR3) under the earthquake simulated by cyclic loading up to 4.4% lateral drift. Hexagonal castellated beams provide lower weight and higher bending strength in comparison with typical wide flange beams in post-tensioned semi-rigid steel connections. The inelastic deformations of the bolted top and bottom angles provide reliable level of energy dissipation, and the steel strands provide self-centering capability and revert the moment-resisting frame to its initial position without residual drift after a severe earthquake. The results of finite element analysis verified against experiment have proved that the theoretical method based on the previous researches accurately predicts the behavior of hexagonal castellated beams in the post-tensioned connections. All beam specimens did not suffer from the flange buckling and web shear buckling under the standard cyclic loading up to 4% lateral drift; likewise, hexagonal castellated beams in the post-tensioned connections showed adequate strength against web-post failure and vierendeel mechanism up until 4% drift. In order to investigate the ultimate failure modes of the specimens, they have also been subjected to an added half-cycle loading up to 4.4% lateral drift beyond the standard loading. The further drifts have leaded to the web-post buckling in most specimens with hexagonal castellated beams and flange buckling in all specimens with wide flange beams. In addition, the parametric study is suggested as a further investigation to comprehensively understand the behavior of hexagonal castellated beams in the PT connections and it is required to reach more general conclusions. This research has developed a benchmark to design hexagonal castellated beams in the PT semi-rigid connections, but a step-by-step design guideline is still required to add it to design codes and specifications for steel structures.

The interaction between reinforcement bars and concrete is particularly essential in predicting the ultimate failure of reinforced concrete (RC) elements. It is particularly important to understand the bond and anchorage behaviour of reinforcement bars with the surrounding concrete. The current codes of practice in designing anchorage length in high-strength concrete (HSC) were scarce and were extrapolated from the experimental results of normal strength concrete (NSC). It has been consistently being reported that the bond and anchorage of bars in HSC are relatively weaker compared to in NSC. Even various studies had been conducted in studying the bond and anchorage in conventional RC but the applications of these codes of practice are unsuitable for HSC. This problem makes a barrier for a widespread utilization of HSC in the construction industries. In view of this, this study reviewed previous studies of bond and anchorage behaviour of reinforced NSC and HSC, their mechanisms and applicability of using confining pressure in developing bond and anchorage in facilitating the research development in bond and anchorage behaviour of RC structures. The findings showed that the confinement is effective in enhancing bond and anchorage between reinforcement bars and concrete but further research is still needed to develop adequate guidelines over a service of long term for RC with lateral or transverse confinement

A multiscale procedure based on asymptotic expansion homogenization (AEH) technique is formulated to study the inelastic deformations and damage of fiber reinforced polymer composite materials (FRP). FRPs show significant inelastic deformation and local phase damage before the ultimate failure point and capturing these accurately using AEH is an active research area. The complex implementation and high computational cost of AEH when used in multiscaling can be alleviated by the reduced order techniques proposed by Oskay and Fish (2007). In the present work, the reduced order AEH formulation is extended to capture the plasticity and damage in the matrix. The initial studies are performed for representative volume element (RVE) which show the behavior as expected. This new formulation is applied to study the low velocity impact of composites. The results (force-time curves and extent of damage) are validated with experiments. The model is successfully able to capture the deflection at various points on the laminate plate and permanent indentation on the surface.