Improvement of bearing performance on exterior steel beam-reinforced concrete column joints with steel column

[EN] To improve the bearing failure behavior of the exterior steel beam-reinforced concrete column joints composed of reinforced concrete columns, joint details using steel column was proposed. Steel column was attached to the lower flanges at right angles to the steel flange. The objective of this study is to clarify the effectiveness of proposed joint details experimentally and theoretically. To clarify the influence of steel column on the bearing failure of the joint, seven T-shaped subassemblages were tested under reversed cyclic loading. All specimens had the same cross sections of the steel beam. The experimental variables were the embedded length of the steel column, whether there is the end plate at the tip of the embedded steel column, and, the arrangement of transverse reinforcement ratio surrounding the steel column. The following remarks can be drawn from the test results. 1) In case of the specimen with a short embedded length of the steel column, the punching shear failure on the upper surface of the steel beam flange was remarkable when the maximum strength was reached. However, in the specimen with long embedded length of steel column, it was not observed the punching shear failure. 2) The maximum strength increased with the embedded length of the steel column. Further, the maximum strength of the specimen with the embedded length of three times of the steel column depths is subjected to bending yield strength of the steel column. 3) It was shown that the transverse reinforcement to surround the steel column and the end plate were necessary to improve the bearing failure of the joint.Nakaue, S.; Nishimura, Y. (2018). Improvement of bearing performance on exterior steel beam-reinforced concrete column joints with steel column. En Proceedings of the 12th International Conference on Advances in Steel-Concrete Composite Structures. ASCCS 2018. Editorial Universitat Politècnica de València. 491-497. https://doi.org/10.4995/ASCCS2018.2018.7077OCS49149

Establishment of a new rehabilitation program using masticatory training food for jaw deformity patients

Background/purpose: Patients with jaw deformities may show a reduction in masticatory function as a result of postoperative hypofunction. This study aimed to establish a novel rehabilitation program using a commercially available masticatory training food for patients with jaw deformities after orthognathic surgery. Materials and methods: Nine patients with mandibular prognathism (the training group: n = 5, and the non-training group: n = 4) and 6 control participants with normal occlusion were included in this study. For the rehabilitation program with masticatory exercise, patients were instructed to chew the training food once a day for 60 days starting from 10 days after the surgery. The effects of the rehabilitation program were assessed by determining the maximum bite force (MBF) and the masticatory performance (MP). Clinical assessments were performed just before orthognathic surgery (Pre) and at 10 days (T0), 1 month (T1), 2 months (T2), and 3 months (T3) after surgery. Results: Compared with the non-training group, the training group showed a trend toward greater recovery amount of MBF from Pre to T3, and a significantly greater recovery amount in MP (p < 0.05) from Pre to T3. When the time-series change of MP was evaluated in both groups from T0 to T3, a significant difference was observed in the interaction terms (p = 0.03). This result indicates that the effectiveness of the training may be demonstrated by following the postoperative course further. Conclusion: The rehabilitation using this training food may become a useful method for postoperative hypofunction in patients with jaw deformities

Identification of key determinant for predicting feasible mandibular molars distalization

Background/purpose: The distal movement of mandibular molar is effective treatment strategy, while it is still difficult to determine if the posterior available space is sufficient or not for mandibular molar distalization before treatment. Thus, this study aimed to identify the measurement items of lateral cephalograms with the potential to accurately predict the posterior anatomical limit of mandibular molar distalization. Materials and methods: Cephalometric images of 26 patients were used. We establish five landmarks: the distal contact point (D7), the distal root apex (R7), the distal tooth cervix (TC) of the mandibular second molar, the anterior border of the ramus (ABR) and the external oblique line of the mandible (E). The D7-ABR and the vertical height between TC and E (TC-V), the distal movements of D7 and R7 during treatment (D7D, R7D) were measured. The subjects were divided into bodily-like and tipping movement group, according to the ratio D7D/R7D. Results: Significant differences in D7D and R7D were found between the bodily-like movement and tipping movement groups (P < 0.01). Moreover, TC-V was significantly larger in the bodily-like movement group (P < 0.01). A positive correlation was found between TC-V and D7D (r = 0.68) and between TC-V and R7D (r = 0.69), indicating that TC-V has the potential to make accurate predictions for D7D and R7D. D7-ABR did not show a positive correlation with R7D. Conclusion: Using TC-V can strengthen the prediction of available posterior space for mandibular molar distalization