Higher Failure Load Research Articles

Experimental Investigation of Metallic Fiber-Reinforced Adhesively Bonded Joints under Bending

In the current paper, the geometric and material parameters of metal fibers utilized for strengthening adhesively bonded single lap joints under flexural loading were investigated by using experimental investigations. According to the test results, incorporating metal fibers in the adhesive layer of a bonded joint can have a significant impact on the flexural load bearing of the joint. The distance between the fibers and also the fibers orientation were considered as the key parameters in this research. It was concluded that the load bearing of the joint can be improved by reducing the distance between the fibers and the highest failure loads were obtained for the joints reinforced by fibers in the longitudinal direction.

Design Guideline for Shear Strengthening of Reinforced Concrete Beam Using CFRP Strip to Eliminate Debonding Failure

Background: Design guideline to obtain the dimension of CFRP laminate for eliminating premature deboning failure is vital to acquire the ultimate strength of shear strengthened reinforced concrete beam. Objectives: The main objective of this research is to offer a design guideline for shear strengthening of reinforced concrete beam using CFRP laminate by eliminating debonding failure. Methods/Statistical Analysis: In the guideline, the design strain of CFRP laminate was obtained based on the bond strength of concrete and finally the beam was designed for shear in accordance with Euro Code (EC 2). To verify the guidelines, three reinforced concrete beams were experimentally investigated including un-strengthened control beam, beam strengthened with proposed guideline and beam strengthened in accordance with ACI 440. Findings: Results showed that the strengthened beam with proposed guideline prevented the complete separation of CFRP shear strips before failed by flexure. The strains of CFRP laminate were found to be compatible with shear reinforcement. Strengthened beam of proposed guideline had 35% and 20% higher failure loads as compared to un-strengthened control beam and strengthened beam with ACI guideline respectively. In terms of design parameters, the proposed guideline had been satisfactorily verified through experimental investigations. Application/Improvements: The proposed guideline is recommended for shear strengthening of RC beam using CFRP laminate. However, future research is suggested to further investigate the effects of concrete cracks on bond strength of concrete. Keywords: CFRP Laminate, Debonding, Design, Shear Strengthening

Bone mass, microarchitecture and strength are influenced by race/ethnicity in young adult men and women

Lower rates of fracture in both Blacks compared to Whites, and men compared to women are not completely explained by differences in bone mineral density (BMD). Prior evidence suggests that more favorable cortical bone microarchitecture may contribute to reduced fracture rates in older Black compared to White women, however it is not known whether these differences are established in young adulthood or develop during aging. Moreover, prior studies using high-resolution pQCT (HR-pQCT) have reported outcomes from a fixed-scan location, which may confound sex- and race/ethnicity-related differences in bone structure. PurposeWe determined differences in bone mass, microarchitecture and strength between young adult Black and White men and women. MethodsWe enrolled 185 young adult (24.2±3.4yrs) women (n=51 Black, n=50 White) and men (n=34 Black, n=50 White) in this cross-sectional study. We used dual-energy X-ray absorptiometry (DXA) to determine areal BMD (aBMD) at the femoral neck (FN), total hip (TH) and lumbar spine (LS), as well as HR-pQCT to assess bone microarchitecture and failure load by micro-finite element analysis (μFEA) at the distal tibia (4% of tibial length). We used two-way ANOVA to compare bone outcomes, adjusted for age, height, weight and physical activity. ResultsThe effect of race/ethnicity on bone outcomes did not differ by sex, and the effect of sex on bone outcomes did not differ by race/ethnicty. After adjusting for covariates, Blacks had significantly greater FN, TH and LS aBMD compared to Whites (p<0.05 for all). Blacks also had greater cortical area, vBMD, and thickness, and lower cortical porosity, with greater trabecular thickness and total vBMD compared to Whites. μFEA-estimated FL was significantly higher among Blacks compared to Whites. Men had significantly greater total vBMD, trabecular thickness and cortical area and thickness, but greater cortical porosity than women, the net effects being a higher failure load in men than women. ConclusionThese findings demonstrate that more favorable bone microarchitecture in Blacks compared to Whites and in men compared to women is established by young adulthood. Advantageous bone strength among Blacks and men likely contributes to their lower risk of fractures throughout life compared to their White and women counterparts.

The tribological properties of the polyurea greases based on oil‐miscible phosphonium‐based ionic liquids

AbstractOil‐miscible phosphonium‐based ionic liquids have recently been attracted much attention. This study is to develop potentional high temperature lubricating greases based on oil‐miscible phosphonium‐based ionic liquids.This lubricating grease is prepared using oil‐IL blend, which was obtained by adding 10wt% oil‐miscible phosphonium‐based ionic liquids into the PAO 40 base oil as base stock. Compared with the traditional PAO 40 polyurea grease, this polyurea grease has a little lower dropping point. Corrosion test results show the polyurea grease that was prepared using phosphonium‐based ionic liquids cations connected with longer alkyl chains that are no corrosion to brass and steel. Most importantly, the polyurea greases demonstrate very promising tribological properties at 150°C, such as low friction coefficient, small wear volume, and high lubrication failure load. Surface characterization revealed the tribochemical film containing iron oxide, and Fe[PO4] was formed on the worn surface.

Development of processing windows for friction stir spot welding of aluminium Al5052 /copper C27200 dissimilar materials

Friction stir spot welding technique was used to join dissimilar combinations of aluminium alloy (Al5052) with copper alloy (C27200) and friction stir spot welding windows such as tool rotational speed–dwell time and tool rotational speed–plunge depth diagrams for effective joining of these materials were developed. Using a central composite design model, empirical relations were developed to predict the changes in tensile shear failure load values and interface hardness of the joints with three process parameters such as tool rotational speed, plunge depth and dwell time. The adequacy of the developed model was verified using ANOVA analysis at 95% confidence level. Response surface methodology was used to optimize the developed model to maximize tensile strength and minimize interface hardness. A high tensile shear failure load value of 3850 N and low interface hardness value of HV 81 was observed for joints made under optimum conditions, and validation experiments confirmed the high predictability of the developed model with error less than 2%. The operating windows developed shall act as reference maps for future design engineers in choosing appropriate friction stir spot welding process parameter values to obtain good joints.

Rigid-foldable tubular arches

Several types of tubular, origami-inspired plate mechanisms have been proposed for use as meta-materials and deployable structures. However, research into mechanical properties of these mechanisms is limited to rectilinear forms. This paper investigates the structural feasibility of non-rectilinear rigid-foldable cellular materials for application as deployable arch structures. An experimental and numerical investigation is first conducted on a new type of folded tubular arch, with failure contributions identified from hinge rotation and plate buckling failure mechanisms. A common geometric description is then developed between three different types of origami-inspired tubular arches, which are numerically investigated under three-point loading. The double-kite arch developed in this paper is seen to have the highest failure load.

Biomechanical testing of transcapsular meniscal repair

BackgroundAll of previous biomechanical studies on meniscal repair have examined the meniscus itself without synovial membrane and capsule, although in the clinical setting, the meniscal repair is generally performed including capsule. Therefore, biomechanical properties of transcapsular meniscal repair are unclear. Thus, this study aimed to clarify the biomechanical properties of transcapsular meniscal repair.MethodsIn 70 porcine femur–medial meniscus–tibia complexes with capsules, longitudinal meniscal tears were repaired using different suture techniques (inside-out or all-inside technique), suture methods (vertical or horizontal methods), and numbers of sutures (single or double). A cyclic loading test between 5 and 20 N for 300 cycles was performed followed by a load-to-failure test.ResultsTears repaired by the all-inside technique presented significantly larger widening (0.88 ± 0.38 mm) than those by the inside-out technique (0.51 ± 0.39 mm) during the cyclic loading test (P = 0.035). The horizontal suture presented significantly lower ultimate failure load (62.5 ± 15.5 N) in the all-inside technique than in the vertical suture (79.7 ± 13.0 N; P = 0.018). The stacked suture had a significantly higher failure load (104.6 ± 12.5 N) than the parallel suture (83.3 ± 12.6 N; P = 0.001). Furthermore, the double suture presented significantly higher failure loads (83.3 ± 12.6 N and 104.6 ± 20.4 N) than the single suture with both inside-out (58.8 ± 8.3 N; P = 0.001) and all-inside (79.7 ± 13.0 N; P = 0.022) techniques.ConclusionsUpon comparison of the suture techniques, the inside-out technique provided a more stable fixation at the repair site than the all-inside technique during the cyclic test. Among the suture methods, the vertical suture had more desirable biomechanical properties than the horizontal suture as demonstrated by smaller widening during the cyclic test and the larger load to failure. The stacked suture created a stronger fixation than the parallel suture. In terms of the number of sutures, the double suture had superior biomechanical properties compared with the single suture.

Ductile fibre reinforced cementitious composites (DFRCC) for improved corrosion durability of reinforced concrete columns

This paper reports the results of an experimental program on the effectiveness of ductile fibre reinforced cementitious composites (DFRCC) in retarding the corrosion of steel, corrosion induced damage and post-corrosion structural behaviour of reinforced concrete (RC) columns. Two series RC columns are included in this program. The first series consists of ordinary RC columns that are subjected to an accelerated corrosion regime. The second series consists of two columns that are similar to first two series in every aspect, except that the ordinary concrete in the column is replaced with a ductile DFRCC material. Two types of DFRCC materials are considered: a hybrid-fibre DFRCC containing 1.5 vol.% PVA fibers and 1 vol.% steel fibers and a mono-fibre DFRCC containing 2.5 vol.% PVA fibers. Specimens of the second series are also subjected to a regime of accelerated corrosion. Corrosion damage, including the possible development of spalling and/or delamination, is monitored in each specimen using a specially-fabricated mechanical expansion collar. Based on the collective findings from theoretically-estimated steel losses, visual recordings of corrosion damage, and measurements of the tendency of cover delaminate, it was concluded that the steel reinforced DFRCC columns had a remarkably higher resistance against reinforcement corrosion compared to the ordinary RC columns. The corrosion damaged DFRCC columns also exhibited about 23–64% higher failure load than that of corrosion damaged RC columns and no sign of spalling of cover of columns in the structural test.

Punching shear behavior of reinforced concrete slabs using steel fibers in the mix

One of the major problems of flat slab is the punching shear failure of slab-column connection. This form of failure must be avoided.Fourteen slab-column connections are tested to failure and categorized in two phases. The first “Phase I” consisted of testing ten interior square slabs axially loaded. The second “Phase II” consisted of testing four specimens under eccentric loading to study the influence of moment transfer at the slab-column connection on the punching shear failure of the slabs. The main parameters evaluated were, fiber volume ratio which was 0.5%, 1.0% and 1.5% and, punching area as dimensions of the square portion of the slab having steel fibers at the column vicinity of lengths d+200mm, 2d+200mm and 3d+200mm. All slabs have same dimensions of 1700mm×1700mm with thickness 150mm and reinforcement ratio of 1.2%. All tested specimens were loaded incrementally up to failure. However using steel fiber increased both the failure load and energy absorbing capacity. Summarily, it was found that slabs with a 1.5% steel fiber ratio led to high failure load capacity. Results showed that using steel fiber only in a portion of slab that is equal to slab thickness from column face was sufficient to give the optimum enhancement in both failure load and ductility behavior. Three-dimensional finite element model was created to using ANSYS R14.5 ANSYS (2012) program to simulate the behavior of the tested specimens. Crack pattern, mode of failure and energy absorption were analyzed here in this study.

An experimental investigation on the failure loads of the mono and bi-adhesive joints

Bi-adhesive (or mixed-adhesive) joint is an alternative stress-reduction technique for adhesively bonded lap joints. In this work, an experimental study was performed to assess the effect of bi-adhesive bondline on the failure load of mono-adhesive and bi-adhesive single-lap joints. The first step in the experimental study related to mono-adhesive joint, the overlap length was checked using the Global yielding criteria. For the selected overlap length, failure loads of AV138, Araldite 2015 and DP-8005 mono-adhesive joints were determined. It was seen that the highest failure load occurred in the Araldite 2015 mono-adhesive joint. Secondly, the bi-adhesive joints were considered as two different adhesive combinations (AV138 + 2015, AV138 + DP-8005). An interesting result was obtained that the considered bi-adhesive joints with two different adhesive combinations (AV138 + 2015, AV138 + DP-8005) give joint strengths higher than the joint strengths of the adhesives used individually, even if ductile adhesive has a joint strength higher than that of the stiff adhesive. In the last step of this study, experimental investigation was then focused on the determination of optimum bond-length ratio for the bi-adhesive joint. Optimum bond-length ratio for bi-adhesive joint was then investigated using three ratios (0.3, 0.5, 0.7). It is concluded that the adhesive type and the bond-length ratio play an important role in the bi-adhesive bondline. Comparisons of the experimentally determined failure loads and shear strengths with available closed-form solutions were also carried out. Experimental failure loads were in good agreement with those obtained from the Volkersen method and Global yielding criteria.

Un essai pilote comparant le comportement à l’arrachement des cupules metal-back vissantes et cimentées en polyéthylène : étude cadavérique cas témoin

BackgroundThe removal of well-fixed acetabular components following total hip arthroplasty (THA) is a difficult operation and could be accompanied by the loss of acetabular bone stock. The optimal method for fixation is still under debate. The aim of this pilot study was to compare the tear-out resistance and failure behavior between osseo-integrated and non-integrated screw cups. Furthermore, we examined examined whether there are differences in the properties mentioned between screw sockets and cemented polyethylene cups. HypothesisTear-out resistance and related mechanical work required for the tear-out of osseo-integrated screw sockets are higher than in non-integrated screw sockets. Patients and methodsTen human coxal bones from six cadavers with osseo-integrated screw sockets (n=4), non-integrated (implanted postmortem, n=3) screw sockets and cemented polyethylene cups (n=3) were used for tear-out testing. The parameters axial failure load and mechanical work for tear-out were introduced as measures for determining the stability of acetabular components following THA. ResultsThe osseo-integrated screw sockets yielded slightly higher tear-out resistance (1.61 ± 0.26kN) and related mechanical work compared to the non-integrated screw sockets (1.23 ± 0.39kN, P=0.4). The cemented polyethylene cups yielded the lowest tear-out resistance with a failure load of 1.18±0.24kN. Compared to the screw cups implanted while alive, they also differ on a non-significant level (P=0.1). Osseous failure patterns differed especially for the screw sockets compared to the cemented polyethylene cups. DiscussionOsseo-integration did not greatly influence the tear-out stability in cementless screw sockets following axial loading. Furthermore, the strength of the bone–implant interface of cementless screw sockets appears to be similar to cemented polyethylene cups. However, given the high failure load, high mechanical load and because of the related bone failure patterns, removal should not be performed by means of tear-out but rather by osteotomes or other curved cutting devices to preserve the acetabular bone stock. Level of evidenceLevel III, case-control-study.

Evaluation of biomechanical properties: are porcine flexor tendons and bovine extensor tendons eligible surrogates for human tendons in in vitro studies?

Porcine flexor tendons, bovine extensor tendons, and human (semitendinosus) tendons are frequently used as substitutes for human ACL grafts in biomechanical in vitro studies. This study compares the biomechanical properties and structural differences of these tendons. In this biomechanical study, fresh-frozen porcine flexor tendons, bovine extensor tendons, and human semitendinosus tendons were used (n=36). The tendons were mounted in a uniaxial testing machine (Zwick/Roell) with cryo-clamps, leaving a 60mm tendon part free between the two clamps. Specimens have been loaded to failure to evaluate the biomechanical parameters stiffness, yield load, and maximum load. A Total Collagen Assay Kit was used to detect differences in the total collagen type I concentration (n=30). A one-way ANOVA was performed to detect differences in the means. The significance level was set at p<0.05. There were no significant differences in the stiffness between the groups (bovine 194±43N/mm, porcine 211±63N/mm, and human cadaveric 208±58N/mm). The yield and maximum loads were high (>1000N) in all groups, but they were significantly increased in both animal specimens (means of 1681-1795N) compared with human cadaveric specimen (means of 1289-1406N; p<0.01). No difference in the collagen type I concentration was detected (N.S.). Porcine flexor and bovine extensor tendons are eligible substitutes with similar stiffness and high failure loads compared with human cadaveric semitendinosus tendons in in vitro studies.

A pilot trial comparing the tear-out behavior in screw-sockets and cemented polyethylene acetabular components – a cadaveric study

BackgroundThe removal of well-fixed acetabular components following THA (total hip arthroplasty) is a difficult operation and could be accompanied by the loss of acetabular bone stock. The optimal method for fixation is still under debate. The aim of this pilot study was to compare the tear-out resistance and failure behavior between osseo-integrated and non-integrated screw cups. Furthermore, we examined whether there are differences in the properties mentioned between screw sockets and cemented polyethylene cups. HypothesisTear-out resistance and related mechanical work required for the tear-out of osseo-integrated screw sockets are higher than in non-integrated screw sockets. Patients and methodsTen human coxal bones from six cadavers with osseo-integrated screw sockets (n=4), non-integrated (implanted post-mortem, n=3) screw sockets and cemented polyethylene cups (n=3) were used for tear-out testing. The parameters axial failure load and mechanical work for tear-out were introduced as measures for determining the stability of acetabular components following THA. ResultsThe osseo-integrated screw sockets yielded slightly higher tear-out resistance (1.61±0.26kN) and related mechanical work compared to the non-integrated screw sockets (1.23±0.39kN, P=0.4). The cemented polyethylene cups yielded the lowest tear-out resistance with a failure load of 1.18±0.24kN. Compared to the screw cups implanted while alive, they also differ on a non-significant level (P=0.1). Osseous failure patterns differed especially for the screw sockets compared to the cemented polyethylene cups. DiscussionOsseo-integration did not greatly influence the tear-out stability in cementless screw sockets following axial loading. Furthermore, the strength of the bone-implant-interface of cementless screw sockets appears to be similar to cemented polyethylene cups. However, given the high failure load, high mechanical load and because of the related bone failure patterns, removal should not be performed by means of tear-out but rather by osteotomes or other curved cutting devices to preserve the acetabular bone stock. Level of evidenceLevel III, case-control-study.

Biomechanical Comparison of Parallel and Crossed Suture Repair for Longitudinal Meniscus Tears.

Background:Longitudinal meniscus tears are commonly encountered in clinical practice. Meniscus repair devices have been previously tested and presented; however, prior studies have not evaluated repair construct designs head to head. This study compared a new-generation meniscus repair device, SpeedCinch, with a similar established device, Fast-Fix 360, and a parallel repair construct to a crossed construct. Both devices utilize self-adjusting No. 2-0 ultra–high molecular weight polyethylene (UHMWPE) and 2 polyether ether ketone (PEEK) anchors.Hypothesis:Crossed suture repair constructs have higher failure loads and stiffness compared with simple parallel constructs. The newer repair device would exhibit similar performance to an established device.Study Design:Controlled laboratory study.Methods:Sutures were placed in an open fashion into the body and posterior horn regions of the medial and lateral menisci in 16 cadaveric knees. Evaluation of 2 repair devices and 2 repair constructs created 4 groups: 2 parallel vertical sutures created with the Fast-Fix 360 (2PFF), 2 crossed vertical sutures created with the Fast-Fix 360 (2XFF), 2 parallel vertical sutures created with the SpeedCinch (2PSC), and 2 crossed vertical sutures created with the SpeedCinch (2XSC). After open placement of the repair construct, each meniscus was explanted and tested to failure on a uniaxial material testing machine. All data were checked for normality of distribution, and 1-way analysis of variance by ranks was chosen to evaluate for statistical significance of maximum failure load and stiffness between groups. Statistical significance was defined as P < .05.Results:The mean maximum failure loads ± 95% CI (range) were 89.6 ± 16.3 N (125.7-47.8 N) (2PFF), 72.1 ± 11.7 N (103.4-47.6 N) (2XFF), 71.9 ± 15.5 N (109.4-41.3 N) (2PSC), and 79.5 ± 25.4 N (119.1-30.9 N) (2XSC). Interconstruct comparison revealed no statistical difference between all 4 constructs regarding maximum failure loads (P = .49). Stiffness values were also similar, with no statistical difference on comparison (P = .28).Conclusion:Both devices in the current study had similar failure load and stiffness when 2 vertical or 2 crossed sutures were tested in cadaveric human menisci.Clinical Relevance:Simple parallel vertical sutures perform similarly to crossed suture patterns at the time of implantation.

Experimental study on compressive behavior of GFRP stiffened panels using digital image correlation

Stiffened composite panels are primary structural components in ship, aircraft and aerospace vehicles. The main objective of this study is to investigate the behavior of glass fiber reinforced polymer (GFRP) composite panels with stiffener runout condition and different stiffener configurations such as blade, T and hat under axial compression. A special fixture was designed and fabricated for the compressive testing of GFRP composite stiffened panels. Fabricated specimens were tested until failure and the effect of different stiffener configurations on the load–deformation behavior is compared. Digital image correlation (DIC) was used to measure the deformations and strains on the GFRP composite panels. Test results indicated that T-stiffeners performed well with higher failure load and stiffness as compared to other stiffeners. DIC results show that the presence of stiffeners reduced the out-of-plane displacement in the stiffened panels. As the load level increases, damage initiates and propagates. The surface strain and displacement are sensitive to damages and it can alter their distribution. This could be captured using DIC technique as the damage distribution takes place. The T-stiffeners were found to be effective in resisting bending strains and produced more uniform distribution of compressive strain compared to other stiffener configuration.

Biomechanical Properties and Microstructural Analysis of the Human Nonaneurysmal Aorta as a Function of Age, Gender and Location: An Autopsy Study

Introduction: The biomechanical failure properties and histological composition of the human nonaneurysmal aorta were studied. Methods: Twenty-six human aortas were harvested from fresh cadavers at autopsy. A total of 153 circumferentially oriented strips were obtained from the aortas for biomechanical and histological studies. Results: The failure load (6.18 ± 2.03 vs. 4.85 ± 2.04 N; p = 0.001), failure tension (19.88 ± 9.05 vs. 14.53 ± 7 N/cm; p = 0.001), failure strain (0.66 ± 0.31 vs. 0.49 ± 0.25; p = 0.003) and amount of elastic fibers (19.39 ± 15.57 vs. 14.06 ± 9.5%; p = 0.011) were all significantly higher for the thoracic than the abdominal aorta. There was a significant negative correlation between age and failure load (R = -0.35; p < 0.0001), failure stress (R = -0.63; p < 0.0001), failure tension (R = -0.52; p < 0.0001) and failure strain (R = -0.8; p < 0.0001). Male aortas had a higher failure load and failure tension than female aortas. Conclusion: The thoracic aorta has a higher strength and elasticity than the abdominal aorta. The elderly have weaker and stiffer aortas than the young. Male aortas are stronger than female aortas.

Fracture resistance of endodontically treated teeth restored with Zirconia filler containing composite core material and fiber posts

Objectives:To assess the fracture resistance of endodontically treated teeth with a novel Zirconia (Zr) nano-particle filler containing bulk fill resin composite.Methods:Forty-five freshly extracted maxillary central incisors were endodontically treated using conventional step back preparation and warm lateral condensation filling. Post space preparation was performed using drills compatible for fiber posts (Rely X Fiber Post) on all teeth (n=45), and posts were cemented using self etch resin cement (Rely X Unicem). Samples were equally divided into three groups (n=15) based on the type of core materials, ZirconCore (ZC) MulticCore Flow (MC) and Luxacore Dual (LC). All specimens were mounted in acrylic resin and loads were applied (Universal testing machine) at 130° to the long axis of teeth, at a crosshead speed of 0.5 mm/min until failure. The loads and the site at which the failures occurred were recorded. Data obtained was tabulated and analyzed using a statistical program. The means and standard deviations were compared using ANOVA and Multiple comparisons test.Results:The lowest and highest failure loads were shown by groups LC (18.741±3.02) and MC (25.16±3.30) respectively. Group LC (18.741±3.02) showed significantly lower failure loads compared to groups ZC (23.02±4.21) and MC (25.16±3.30) (p<0.01). However groups ZC (23.02±4.21) and MC (25.16±3.30) showed comparable failure loads (p=0.23).Conclusions:Fracture resistance of endodontically treated teeth restored with Zr filler containing bulk fill composite cores was comparable to teeth restored with conventional Zr free bulk fill composites. Zr filled bulk fill composites are recommended for restoration of endodontically treated teeth as they show comparable fracture resistance to conventional composite materials with less catastrophic failures.

Numerical and Experimental Analysis of Adhesively Bonded Stiffened Panels Subjected to In-Plane Compression Loading

This paper presents a numerical and experimental study on the pre and post-buckling behavior of adhesively bonded stiffened panels subjected to in-plane compression loading. An experimental programme was carried out to characterize the buckling load, buckling modes and collapse loads. The mechanical tests were performed in the Aerospace Structures Laboratory at ITA. The structural performance of the bonded stiffened panels in terms of buckling and collapse loads was compared to conventional riveted stiffened panels. Finite element models accounting for material, geometrical nonlinearities as well as progressive failure in the bonded interface were developed and validated experimentally. A good agreement between numerical and experimental results was found for buckling and collapse loads through number of semi-waves and measured strains. The experimental and numerical results indicate a superior performance in buckling load and failure load of the bonded stiffened panels over the riveted panels. Both numerical and experimental results showed that the bonded stiffened panels had over 19% higher failure load in comparison with the riveted panels.

Structural behaviour of pultruded fibre composites guardrail system under horizontal loading

Fibre composite guardrails are increasingly being used to ensure safety of workers from fall-from-height incidents due to its high strength, high corrosion resistance and low maintenance. In this study, the structural behaviour of pultruded glass fibre-reinforced polymer (GFRP) guardrail was evaluated following AS1657-1992. GFRP guardrail systems mounted on top and side of a steel beam with different joint connectors are loaded horizontally to top of the guardrail post and to the middle of the guardrail member. The results showed that the guardrail system with joints connected with either polypin or rivets combined with epoxy exhibited 20% higher failure load and almost double the stiffness than those connected using polypin or rivets alone. The side-mounted guardrail failed due to failure of the base connector while the guardrail mounted on top of the beam failed at the joints indicating that the structural behaviour of GFRP guardrail system is affected mainly by the type of joints.

Textile-reinforced concrete facade panels with rigid foam core prisms

Textile-reinforced concrete (TRC) is a material that is gaining new ground in the field of construction where it not only allows for the manufacture of reduced lightweight structures but also eliminates the problem of corrosion by using alkali-resistant textile reinforcement. The aim of this paper is to investigate the bending behaviour of a newly developed TRC facade panel that incorporates polystyrene foam prisms. Numerical simulations were employed in order to choose the geometry and repartition of prisms inside the facade panel. Experimental results revealed a reduced amount of concrete by 20% via the use of rigid foam prisms with a higher failure load by 16% but a lower elasticity limit by 49% in comparison with the regular facade panels.