Modeling of RC shear walls strengthened by FRP composites

Dynamic contribution of CFRP strips to CFRP-strengthened RC shear walls

Research on seismic performance of precast steel–concrete composite tube shear walls with horizontal joint

To improve outcomes of anterior cruciate ligament reconstruction (ACLR), it is important to understand the reasons for failure of this procedure. This systematic review was performed to identify current failure modes of ACLR. A systematic search was performed using PubMed, EMBASE, Cochrane, and annual registries for ACLR failures. Studies were included when failure modes were reported (I) of ≥ 10 patients and (II) at a minimum of two-year follow-up.Modes of failure were also compared between different graft types and in femoral tunnel positions. This review included 24 cohort studies and 4 registry-based studies (1 level I, 1 level II, 10 level III, and 16 level IV studies). Overall, a total of 3657 failures were identified. The most common single failure mode of ACLR was new trauma (38%), followed by technical errors (22%), combined causes (i.e. multiple failure mechanisms; 19%), and biological failures (i.e. failure due to infection or laxity without traumatic or technical considerations; 8%). Technical causes also played a contributing role in 17% of all failures. Femoral tunnel malposition was the most common cause of technical failure (63%). When specifically looking at the bone-patellar tendon-bone (BPTB) or hamstring (HT) autografts, trauma was the most common failure mode in both, whereas biological failure was more pronounced in the HT group (4% vs. 22%, respectively). Technical errors were more common following transtibial as compared to anteromedial portal techniques (49% vs. 26%). Trauma is the single leading cause of ACLR failure, followed by technical errors, and combined causes. Technical errors seemed to play a major or contributing role in large part of reported failures, with femoral tunnel malposition being the leading cause of failure. Trauma was also the most common failure mode in both BPTB and HT grafts. Technical errors were a more common failure mode following transtibial than anteromedial portal technique. IV.

Guide catheter extensions (GCEs) are commonly used to facilitate percutaneous coronary interventions (PCIs). We investigated the incidence and modes of failure of GCEs.. Data from the Manufacturer and User Facility Device Experience (MAUDE) database between 2012 and 2022 were used to investigate the most common modes of failure and related adverse events with the use of GCEs. We performed analysis of 4 commonly used catheters: GuideLiner (Teleflex), Guidezilla (Boston Scientific), TrapLiner (Teleflex), and Telescope (Medtronic). The first event reported for GuideLiner was in 2012, Guidezilla in 2018, TrapLiner in 2017, and Telescope in 2019. During the study period, a total of 651 events were reported to the database. A total of 429 true GCE device failures were identified: 59 (14%) for GuideLiner, 297 (69%) for Guidezilla, 47 (11%) TrapLiner, and 26 (6%) for Telescope. Catheter detachment or fracture was the most frequently reported device failure for all 4 GCEs; these failures included shaft fractures, tip deformations, and collar detachments. We identified 222 reported events as unspecified adverse events; these events included device-to-device incompatibility, difficulty to advance, and device fractures outside the patient body. Only 58 (8.9%) events resulted in patient complication. Of these, coronary artery dissection was the most frequently reported complication. Device detachment/fracture is the most common mode of device failure in all 4 GCEs, and coronary dissection is the most common patient complication.

Seismic performance of flexure-dominated reinforced-engineered cementitious composites coupled shear wall

Experimental and numerical investigations on concentrated-hollow RC shear walls

Massive endoprostheses provide orthopaedic oncologists with many reconstructive options after tumor resection, although failure rates are high. Because the number of these procedures is limited, failure of these devices has not been studied or classified adequately. This investigation is a multicenter review of the use of segmental endoprostheses with a focus on the modes, frequency, and timing of failure. Retrospective reviews of the operative databases of five institutions identified 2174 skeletally mature patients who received a large endoprosthesis for tumor resection. Patients who had failure of the endoprosthesis were identified, and the etiology and timing of failure were noted. Similar failures were tabulated and classified on the basis of the risk of amputation and urgency of treatment. Statistical analysis was performed to identify dependent relationships among mode of failure, anatomic location, and failure timing. A literature review was performed, and similar analyses were done for these data. Five hundred and thirty-four failures were identified. Five modes of failure were identified and classified: soft-tissue failures (Type 1), aseptic loosening (Type 2), structural failures (Type 3), infection (Type 4), and tumor progression (Type 5). The most common mode of failure in this series was infection; in the literature, it was aseptic loosening. Statistical dependence was found between anatomic location and mode of failure and between mode of failure and time to failure. Significant differences were found in the incidence of failure mode Types 1, 2, 3, and 4 when polyaxial and uniaxial joints were compared. Significant dependence was also found between failure mode and anatomic location in the literature data. There are five primary modes of endoprosthetic failure, and their relative incidences are significantly different and dependent on anatomic location. Mode of failure and time to failure also show a significant dependence. Because of these relationships, cumulative reporting of segmental failures should be avoided because anatomy-specific trends will be missed. Endoprosthetic design improvements should address failure modes specific to the anatomic location.

Anti-collapse performance of concrete-filled steel tubular composite frame with RC shear walls under middle column removal

Why Do Medial Unicompartmental Knee Arthroplasties Fail Today?

For centuries timber has been the most popular construction material. However, over the last few decades, it gave way to man-invented structural materials, it is still willingly used in civil engineering, commonly for roof constructions, ceilings but also small bridges, lookout towers. Sometimes, as a result of environmental deterioration or changes in load conditions, timber structure requires to be strengthened. Flexural or tensile performance could be simply increased by using external fiber reinforced plastic (FRP) composite sheets or strips. Such type of reinforcement almost does not change the geometry, but uncovered may be exposed to environmental influences including sunrise heating. Its temperature can exceed 70°C, while commonly as save is considered temperature below 45°C. Paper describes the bending tests of timber beams externally strengthened with three types of composites: unidirectional CFRP sheet, CFRP strip and SRP tape. Beams were heated in the various ranges of temperatures and tested in flexure. Among nine tested beams only one, heated to 95°C failed by delamination of composite overlay, the remaining beams reinforced with CFRP strips and SRP tapes could not be destroyed due to deflection outside the press cylinder range, while beams strengthened with CFRP sheets failed after rupture of carbon fibers. Experiment results show that independently of the type of reinforcement danger temperatures can be recognized over 90°C. Under that temperature behaviour of heated beams is only slightly worse than tested in room temperature and differences are visible in deflections. As a result of slippage in the adhesive layer weakened by temperature measured deformation growths. This trend applies to both CFRP strip and sheet strengthened specimens. It should be emphasized that the obtained results are much better than in the case of commonly tested reinforced concrete beams, which were subjected to delamination failure just a little above 65°C.

Background Revision anterior cruciate ligament (ACL) reconstruction has worse outcomes than primary reconstructions. Predictors for these worse outcomes are not known. The Multicenter ACL Revision Study (MARS) Group was developed to perform a multisurgeon, multicenter prospective longitudinal study to obtain sufficient subjects to allow multivariable analysis to determine predictors of clinical outcome. Purpose To describe the formation of MARS and provide descriptive analysis of patient demographics and clinical features for the initial 460 enrolled patients to date in this prospective cohort. Study Design Cross-sectional study; Level of evidence, 2. Methods After training and institutional review board approval, surgeons began enrolling patients undergoing revision ACL reconstruction, recording patient demographics, previous ACL reconstruction methods, intra-articular injuries, and current revision techniques. Enrolled subjects completed a questionnaire consisting of validated patient-based outcome measures. Results As of April 1, 2009, 87 surgeons have enrolled a total of 460 patients (57% men; median age, 26 years). For 89%, the reconstruction was the first revision. Mode of failure as deemed by the revising surgeon was traumatic (32%), technical (24%), biologic (7%), combination (37%), infection (<1%), and no response (<1%). Previous graft present at the time of injury was 70% autograft, 27% allograft, 2% combination, and 1% unknown. Sixty-two percent were more than 2 years removed from their last reconstruction. Graft choice for revision ACL reconstruction was 45% autograft, 54% allograft, and more than 1% both allograft and autograft. Meniscus and/or chondral damage was found in 90% of patients. Conclusion The MARS Group has been able to quickly accumulate the largest revision ACL reconstruction cohort reported to date. Traumatic reinjury is deemed by surgeons to be the most common single mode of failure, but a combination of factors represents the most common mode of failure. Allograft graft choice is more common in the revision setting than autograft. Concomitant knee injury is extremely common in this population.

Experimental and numerical investigation on the seismic behaviors of RC shear walls with multiple post-openings before and after strengthening by steel plates

Shear wall systems are one of the most commonly used lateral load-resisting systems in high-rise buildings. Traditionally, high–thickness ratio of RC shear wall is larger than 8. To investigate the seismic performance of a T-shaped shear wall structure, a total of nine 1/2-scaled models were tested under cyclic loading. The variation of high–thickness ratio was from 4 to 9. All models were loaded in the web, except one specimen loaded in the flange. The axial load ratio was in the range from 0.1 to 0.3. The failure process, failure mode and deformation properties of the specimens were presented herein. The test results showed that the T-shaped shear walls had better ductility than traditional RC shear walls. Meanwhile, the ductility of the model did not change consistently with the axial load ratio and high–thickness ratio. Further, the best seismic performance was achieved when the axial load ratio and high–thickness ratio were within a certain range. The ductility and energy dissipation capacity of the specimen with axial load ratio of 0.2 and high–thickness ratio of 6.5 were the best.

SUMMARYShear wall systems are one of the most commonly used lateral‐load resisting systems in high‐rise buildings. The height–thickness ratio of traditional RC shear wall is more than 8. In order to study the seismic performance of a new type of shear wall structure (short‐limb shear wall structure) with height–thickness ratio of 5–8, L‐shaped cross‐section. A total of six shear wall specimens with 1/2‐scaled model were tested under the cyclic loading. The test parameters included: six specimens were loaded in the web plane; axial–load ratio and height‐thickness ratio were in the range of 0.1–0.4 and 5–8, respectively. The failure process, failure mode and deformation properties were studied. The test results are shown that: L‐shaped RC shear wall with a better deformation than the traditional shear wall, when the axial‐load ratio and height‐thickness ratio are within a certain range, the seismic performance will be able to play to the best. Specimens of the axial‐load ratio of 0.1, height‐thickness ratio of 6.5, they have the most excellent ductility and energy dissipation capacity. Copyright © 2010 John Wiley &amp; Sons, Ltd.

Finite element modeling of RC shear walls strengthened with CFRP subjected to cyclic loading