Fatigue loading characteristic for the composite steel-concrete beams

During the past few decades, composite beams (steel I beam and concrete slab) have had a wide range of uses, particularly in bridge construction. This is due to its relatively low economic cost compared to individual steel structures or reinforced concrete structures. This type of bridges in particular and many similar industrial structures in general are repeatedly subjected to fatigue loads, and that is frequently, as a result of the vehicles passing on these bridges or the vibrations caused by the machines in the industrial facilities. It has been observed during the successive studies that they have been interested in studying this problem that it is concerned with the external structural behavior of these beams  such as a load –deflection relation, observing the cracks appearing during the failure stage and the strain in the steel and concrete flanges. Hence, in this study we have focused on several factors affecting mode of failure of these beams under the fatigue loads, and the common element in all stages of failure was the shear stud, specifically the welding collar at the base of this stud as it is a structurally weak region

Clinical Evaluation of Denture Retention by Multi-suction Cup and Denture Adhesive

AIM: The aim of the study was to compare the retention of two modalities: Multi-suction cup denture, and denture adhesive and to evaluate the change of retention by different time intervals. PATIENTS AND METHODS: Twelve completely edentulous patients were selected. The patients received two dentures: One conventional denture, and the other with multi-suction cups. The retention was measured by a universal testing machine at insertion, 15 min, 30 min, 1 h, 2 h, and 4 h. All values were recorded in Newtons. Statistical analysis was carried out using two-way analysis of variance with post hoc Tukey’s test. RESULTS: Retention was higher in denture adhesive than multi-suction cup, and the change of retention was not statistically significant by time. CONCLUSION: Denture adhesive showed better retention clinically and simplified laboratory procedures than multi-suction denture

Seismic response of a model soil-pile-bridge system in cohesive soil

This paper investigates the dynamic response of a model pile-soil-bridge system subjected to seismic loading using a finite element model (FEM) developed in OpenSees. The numerical model is validated against shake table test data from a companion experimental study, which tested a piles-bridge model fabricated from organic glass. The bridge model comprised four piers, each supported by two-by-two pile groups, with edge piers featuring 60 × 60 mm rubber pads between the pier and deck. Two earthquake ground motions, El Centro and Tianjin, were applied at three intensity levels. The calculated and measured responses show good agreement. The validated FEM reveals that the El Centro earthquake typically induces higher acceleration and moment responses in structural elements compared to the Tianjin earthquake, while the Tianjin earthquake results in greater displacement responses. These findings highlight the impact of earthquake wave characteristics, such as predominant period, on the bridge system\u27s response. Furthermore, the bending moments at the pier top for edge piers remain relatively consistent across different earthquake motions and intensity levels, indicating the role of rubber pads in mitigating seismic forces in the piers

A Comparative study between Different Treatment Modalities of Floating Knee Jnjury At Aswan University Hospital

Purpose: The study aimed at presenting a comparison between the modalities of treatment different of floating knee injury at Aswan University Hospital.  Materials and Methods:  This study is a prospective study including all of our 20 cases of floating knee injuries who were treated utilizing various treatment modalities at Aswan University Hospital between December 2018 and September 2019 with a follow-up period of 12 months  Results: Based on the data analysis,  nailing is a better modality in floating knee injury (especially with diaphyseal long bone). Moreover, plating is a good choice for distal fractures, the external fixator is considered a choice for limb saving(as in popliteal ischemia, open fractures(OG3), and compartment syndrome).  Conclusion: Management of floating knee injury is critical as floating knee injury is not like other fractures. Floating knee injuries are serious injuries with a high rate of complications. Besides being caused by high-energy trauma with extensive skeletal and soft tissue damage, they are also associated with potentially life-threatening injuries of the head, chest, and abdomen. There are multiple controversies in surgical management starting from choosing suitable fixation for each patient according to variable conditions.  Floating knee injury remains a challenging orthopedic problem in which regaining good knee function outcome is a major concern. Stable osteosynthesis to achieve rigid fixation and early mobilization should always be attempted

Improvement of Cell Wall Degrading Enzymes Production by Alginate Encapsulated Trichoderma spp.

Conidia of three Trichoderma isolates were formulated to make alginate pellets with or without 0.5 % chitin or dried fungal mycelium of Fusarium oxysporum as carbon source. The formulations were compared for their ability of in vitro chitinase and β-1,3-glucanase production with free fungal spore suspensions. Conidia entrapped in alginate with or without adjuvant showed high production of enzymes (especially for chitinase) even when repeated 4 times. The addition of chitin or dried fungal mycelium as adjuvant enhanced the enzyme production up to 5 and 2-fold for chitinase and β-1,3-glucanase, respectively. Alginate concentration and surface area of the beads affected the enzyme production. The optimum initial pH, incubation time and temperature were pH=6, 12 days and 40 °C for chitinase, and pH=7, 10 days and 35 °C for β-1,3-glucanase production. The improvement of cell wall degrading enzyme production by alginate encapsulated Trichoderma could explain the in vivo inhibitory effect of such formulations on the target phytopathogenic fungi

STR-990: SUSTAINABLE GROUTED HELICAL PILES: MATERIALS AND PERFORMANCE

Cementitious materials are widely used as a construction material all over the world. However, cement industry has high environmental impact such as the release of CO2 and the consumption of natural resources for its manufacturing energy. Therefore, reducing cement consumption is vital to achieve sustainable green construction practices. In this study, the effects of using treated oil sand waste (TOSW) as a partial replacement of cement in grouted helical pile applications were investigated. Fresh and hardened properties of the green grout incorporating different percentages of TOSW were evaluated. In addition, a model scale grouted helical pile with the green grout was tested to characterize its performance. The experimental results show that the properties of TOSW grout mixes were comparable to conventional grout and satisfy the strength and construction requirements of grouted piles. Moreover, tested grouted helical pile using the developed mixture exhibited similar geotechnical performance as those installed using conventional grout mix. Hence, TOSW can be implemented in grouted helical pile applications, which would assist in achieving sustainable construction