Mechanical Properties of ASTM A572 Grades 50 and 60 Steels at High Temperatures

Studies involving the mechanical properties of high-strength steel (HSS) at elevated temperatures have received considerable attention in recent years. However, current research on HSS at high temperatures is lacking. As a result, the design of fire-protective steel structures with high standards is not sufficiently conservative or safe. This study investigates the effect that elevated temperatures have on the mechanical properties of ASTM A572 Gr. 50 and 60 steels. Reduction factors for the yield strength, tensile strength, and elastic modulus were derived and compared with the standard (AISC, EN1993-1-2) and previous studies (NIST). This study also provides extensive data on the reduction factors for the yield strength, tensile strength, and elastic modulus of mild steel (MS), HSS, and very-high-strength steel (VHSS). The reduction factor for the yield strength was analyzed by expanding the strain level up to 20%. Equations for the yield strength, tensile strength, and elastic modulus were proposed. In future studies, various strains should be analyzed according to the grade of the steel, with the derivation of a reduction factor that considers the plastic strain of the steel. Hence, the findings reported in this study generated a database that can be applied to fire safety design or performance-based fire-resistant design.

Estimation of truck reduction factors applicable to calculation of parameters of a regulated intersection

Introduction. The rapid growth of the country’s car park and the increasing rate of traffic volume lead to various types of transport problems. This is especially acute in regulated areas located near logistics parks, as well as in industrial zones of cities. Here, in the general traffic flow, trucks prevail, which differ from passenger cars primarily in their overall dimensions and dynamic characteristics. For the uniformity of the traffic flow, a certain difference is compensated by specialized coefficients of converting to a conventional passenger car. The performed research is aimed at establishing the main methods used in bringing freight vehicles to a conventional passenger car and assessing the current coefficients of converting freight vehicles to a conventional passenger car by determining the value of the reduced traffic intensity.Methods and materials. Within the framework of the study performed, natural methods of data collection were used for the subsequent calculation. When analyzing certain parameters, mathematical models have been established that underlie certain values of the coefficients of converting trucks to a conventional passenger car.Results. In the course of the study, the authors classified the methods for determining the coefficients of bringing a truck to a conventional passenger car. The values of the reduction factors for some of them have been established, which can be used when calculating the parameters of the regulated section. The present value of road traffic on the set object of the study - the regulated intersection - has been calculated using different actuation coefficients established earlier. The results obtained are assessed.Conclusion. The analysis of the values obtained as a result of calculations showed their significant difference from each other with a difference of 12%, 53% and 300% of the value of the total (not reduced) intensity. Based on the results obtained, the main tasks of further research are determined.

Influence of Mechanical Damage under Repeated Loading on the Resistance of Geogrids against Abrasion

Geogrids are building materials widely used for soil reinforcement that can be affected by the action of many degradation agents throughout their service life. The potential negative effect of the degradation agents should be properly estimated and accounted for during the design phase. The main aim of this work was to study the influence of mechanical damage under repeated loading on the resistance of geogrids against abrasion. Three geogrids (one extruded and two woven) were exposed in isolation to mechanical damage under repeated loading and abrasion tests, followed by the successive exposure to both degradation tests. The damage suffered by the geogrids was evaluated by visual inspection and by tensile tests. Based on the changes found in tensile strength, reduction factors were determined. The reduction factors obtained directly from the successive exposure were compared to those resulting from a method in which the reduction factors obtained for the isolated effect of each degradation agent were multiplied. Results indicated that the abrasion process tended to be affected by a previous exposure to mechanical damage under repeated loading and that the multiplication of the reduction factors obtained for the isolated effects of the degradation agents may not correctly represent their combined effect.

Assessment of Response Reduction Factors Of Reinforced Concrete Buildings Using Response spectrum Analysis

This study provides an in-depth comparative review of the response reduction factors per NBCC 2015 code used to reduce the elastic response of the structure. An assembly of eight (8) reinforced concrete buildings of which four (4) different Seismic Force Resisting System (SFRS) types was included. The models were also categorized based on ductility and overstrength characteristics specifically ductile and conventional construction moment frames as well as ductile and conventional construction shear walls. All eight (8) models were analyzed using elastic Response Spectrum Analysis (RSA). Each SFRS was also analyzed as both a 12 storey and 40 storey building in order to explore the effects / restrictions of building height. The Equivalent Lateral Force Procedure was performed on the assembly of models for comparison to determine if the static procedure as per NBCC 2015 provisions resulted in overly conservative or similar results. The relevant structural response such as base reactions, storey drifts, storey forces, and member forces were recorded and analyzed.