Structural Timber Connections with Dowel-Type Fasteners and Nut-Washer Fixings: Mechanical Characterization and Contribution to the Rope Effect

Dowel-type fasteners are one of the most used type of connections in timber joints. Its design follows the equations included in the Eurocode 5. The problem with these equations is that they do not adequately contemplate the resistive capacity increase of these joints, when using configurations which provoke the so-called rope effect. This effect appears when using threaded surface dowels instead of flat surface dowels, expansion kits or nut-washer fixings at the end of the dowel. The standards consider this increase through a constant value, which is a poor approximation, because it is clearly variable, depending on the joint displacement and because is much bigger, especially when using nut-washer fixings. It is also very important because of the rope effect trigger interesting mechanisms that avoids fragile failures without warning of the joints. For these reasons, it is essential to know how these configurations work, how they help the joint to resist the external loads and how much is the increase resistance capacity in relationship with the joint displacement. The methods used to address these issues consisted of a campaign of experimental tests using actual size specimens with flat surface dowels, threaded surface dowels and dowels with washer-nut fixings at their ends. The resistance capacity results obtained in all the cases has been compared with the values that will come using the equations in the standards. After the tests the specimens were cut to analyze the timber crushings, their widths, the positions and level of plasticizations suffer in the steel dowels and in the washer-nut fixings and the angle formed in the dowel plastic hinges. With all this information the failure mode suffered by the joints has been identified and compared with the ones that the standards predict. The results for the size materials and types of joints studied shows that the crush width average values go from 20 mm with flat surface dowels, to 24 mm in threaded to 32 mm in threaded with washer-nut fixings. The rope effect force/displacement goes from 100 N/m in threaded surface dowels to 500 N/m in threaded with washer-nut fixings. Finally, the load capacities are on average 290% higher those indicated in the standard. The main conclusion is that the rope effect force should be considered in the standards in more detail as a function of multiple variables, especially the displacement of the joint.

CIS-ATRACURIUM WITH MASSETER MUSCLE SPASM: AN UNANTICIPATED DIFFICULT ENDOTRACHEAL INTUBATION AND TEMPOROMANDIBULAR JOINT DISPLACEMENT: A CASE REPORT

Masseter muscle spasm and displacement of temporomandibular joint under anaesthesia could be life threatening if an anaesthesiologist is not prepared. We present a case of 23 years old young lady, who otherwise healthy, having symptoms of abdominal pain and vomiting. Initial baseline workup showed a solitary gallstone and was then planned for urgent laparoscopic cholecystectomy. The challenges faced in the perioperative period were the management of unanticipated masseter muscle spasm and difficult endotracheal intubation after administration of cisatracurium, and temporomandibular joint displacement.

ANALISIS STRUKTUR MOORING DOLPHIN KAPASITAS KAPAL 2000 GT (STUDI KASUS PELABUHAN MUNSE SULAWESI TENGGARA)

Sea transportation is the main transportation used by residents in the islands. The development of marine transportation facilities is expensive to support these activities. Therefore, several alternatives are needed to streamline construction costs, one of which is the construction of a pier using a mooring dolphin. The purpose of this study is to calculate the structural strength of the mooring dolphin with a ship capacity of 2000 GT at Munse Port, Southeast Sulawesi Province. Structural analysis is carried out by analyzing pile capacity and joint displacement analysis. The calculation of the strength of the pile elements at the pier was analyzed using the SAP 2000 program. For soil which is modeled as an elastic support, the ability to support the load depends on the magnitude of the modulus of subgrade reaction from the soil. Embedded pile modeling is modeled with a nonlinear spring force. The results of the analysis by analyzing the capacity of piles with dimensions of 508 mm with a thickness of 12 mm resulted in a capacity ratio of 0.72. The results of the analysis of joint displacement in service or operational conditions are 37.09 mm and in earthquake conditions, they are 13.01 mm.

Venting the Central Compartment of the Hip Prior to Distraction Minimizes Overall Hip Distraction Forces

Objectives: Arthroscopic hip surgery requires application of ipsilateral lower extremity traction to achieve adequate joint distraction and hip central compartment access. Higher traction forces applied to the lower extremity allow greater hip joint distraction, improving the working space, in order minimize iatrogenic chondral and labral injury. However, greater traction forces have demonstrated a higher potential for iatrogenic traction related injuries. Controversy exists about the clinical relevance of procedural modifications, such as venting the hip, as a means of reducing the amount of traction force required to safely distract the hip joint. This study was designed to evaluate the difference between no venting versus venting the hip prior to application of traction on the overall amount of traction needed to distract the hip joint during hip arthroscopy. Methods: A total of 55 hips in 54 consecutive patients undergoing primary arthroscopic hip surgery were retrospectively reviewed. Prior to any instrumentation, interval fluoroscopic images of the operative hip joint were taken at 0, 25, 50, 75, and 100 pound-force (lb-f) (0, 11.3, 22.7, 34.0, and 45.4 kilogram-force (kg-f)) of applied traction. The hip was then taken off traction and the joint was vented using a standard hip access 14-gauge spinal needle and injected with 20 milliliters of air. Before any additional intervention, traction was again applied to the operative extremity and fluoroscopic images were obtained at the same traction force intervals. Joint displacement was measured at each traction force interval both before and after venting. Fluoroscopic images were scaled based on AP pelvis radiographs in order to obtain millimeteric joint space measurements. Results: The mean difference in hip joint displacement without venting and with venting was 0.29, 2.24, 4.06, 4.13, and 3.80mm at 25, 50, 75, and 100 lbs-f of traction, respectively. Paired samples t-testing demonstrated statistically significant increases in distraction distance (p<0.01) at all levels of traction (Table 1). Prior to venting, 0%, 7.3%, 27.8%, 44.0% of hips distracted at least 10 mm at 25, 50, 75, and 100 lbs-f of traction, respectively. After venting, 14.6%, 45.0%, 74.0%, 86% of hips distracted at least 10 mm at 25, 50, 75, and 100 lbs-f of traction, respectively (Figure 1). Conclusion: This study demonstrates that venting the hip prior to the application of traction significantly increases the amount of distraction distance achieved for a given traction force at multiple levels of traction. With venting of the hip, the percentage of hips achieving at least 10mm of distraction for 100lbsf almost doubled. These findings suggest venting the hip prior to application of traction could serve to reduce the maximal amount of traction required to safely instrument the hip arthroscopically. [Table: see text][Figure: see text]

Evaluation of Sheet-Coated Composite Waterproofing Joint Types by Analysis of Tensile Strength Change and Concrete Displacement Resistance Testing under Environmental Degradation

Sheet-coated composite waterproofing (SCCW) have been developed to overcome the natural weakness of singly-ply coating or sheet waterproofing systems for roofing, but there are currently multiple types of SCCW joints. Conventional standard tensile strength testing results show that all SCCW joint types seem to pass the minimum requirement and current selection of SCCW type is dictated on the principle of ‘higher tensile strength is better’, but it has not been experimentally studied as to which type is the optimal to respond to environmental degradation while under the effect of zero-span tensile stress occurring during concrete joint displacement. In this study, five types of SCCW joints were tested: Overlap Bond (OB) type, Overlap Heated-Air Welding (OH) type, Butt Joint I Type (BI), Butt Joint T Type (BT), and Butt Joint Separation Movement Type (BS). These types of joint designs were subjected to Alkali, NaCl, and H2SO4 exposure, and temperature change (60 °C and −20 °C) for determining changes to tensile strength in the joint section. Tensile strength change results are compared to joint displacement resistance test results of specimens that were treated with chemical and temperature degradation. With the exception of chemical exposure conditioning, the Overlap type joints generally had higher tensile strength compared to the butt joint types, but joint displacement test results showed the opposite results, suggesting that complex joints found in SCCW require new evaluation method for quality assessment.

Seismic Effectiveness of Multiple Seismic Measures on a Continuous Girder Bridge

Seismic hazards, such as bridge pounding, unseating, collapse, etc., cause significant economic losses and affect traffic and safety. Research on seismic measures, such as limiting and unseating prevention devices for the bridge, can effectively prevent damage to the bearings, such as excessive displacement, the pounding of the beam end, etc., in an earthquake. In this paper, the dynamic time-history analysis method was used to study the mechanical behaviors of the bridge structure, such as its seismic performance, structural displacement, pier bending moment, etc. We found that different combinations of seismic measures can effectively reduce the displacement at the bridge expansion joint and bearings. The joint application of an expansion device, restrainer, and unseating prevention devices shows the best limiting effect on bridge displacement and expansion joint displacement. The maximum reduction of bridge expansion joint displacement reaches 48% and is within the allowable deformation range of an expansion device in a large earthquake, and the maximum reduction of bearing displacement reaches 34%, which only slightly exceeds the shear deformation of the bearing. The expansion device, restrainer, and unseating prevention devices have smaller internal forces in this case than other cases, without damage. In contrast to the previous studies on single seismic measures of unseating restrainers, this study investigates the combination of multiple seismic measures and earthquakes of various magnitude. It reveals the catastrophe process of the bridge structure and the cooperation law of seismic measures in an earthquake.

Reliability of two-dimensional measures associated with bilateral drop-landing performance

The aim of this study was to establish the within-session reliability for two-dimensional (2D) video analysis of sagittal- and frontal-plane measures during bilateral drop-landing tasks. Thirty-nine recreational athletes (22 men, 17 women, age = 22 ± 4 years, height = 1.74 ± 0.15 m, body mass 70.2 ± 15.1 kg) performed five bilateral drop-landings from 50, 100 and 150% of maximum countermovement jump height, twice on the same day. Measures of reliability for initial contact angle, peak flexion angle and joint displacement for the hip, knee, and ankle joints, frontal-plane projection angles (FPPA), as well as inter-limb asymmetries in joint displacement were assessed. No systematic bias was present between trials (P>0.05). All kinematic measurements showed relative reliability ranging from large to near perfect (ICC = 0.52–0.96). Absolute reliability ranged between measures, with CV% between 1.0–1.6% for initial contact angles, 1.9–7.9% for peak flexion angles, 5.3–22.4% for joint displacement, and 1.6–2.3% for FPPA. Absolute reliability for inter-limb asymmetries in joint displacement were highly variable, with minimal detectable change values ranging from 6.0–13.2°. Therefore, 2D video analysis is a reliable tool for numerous measures related to the performance of bilateral drop-landings.