Aims and Scope
Currently, research and market needs are aimed at the production of more and more specific mortars and concrete with the best properties and mix design directed towards increasingly specific uses.
This research starts with a discussion on cement and aggregate assortments, which are the basic properties of mortars.
The choice of suitable additives able to correct the rheological, workability and resistance properties of the mixture is focused.
In this framework, the current research activity involves some experimental laboratory tests on cement mortars manufactured with hemp flour, intended as a “natural” additive. The aim is the search for any improvements given by the hemp flour to the physical and/or mechanical performances of the tested mortars.
Hemp flour, due to bonding properties, increases the compactness, and therefore, the resistance to environmental factors by the examined cement mortars. The rheological features of mixtures with different percentages of hemp flour, whose maximum water percentage absorbed was resulted to be 125%, were investigated. It was found that standardised sand reduces shrinkage phenomena of tested specimens. Moreover, the compression and bending moment behaviour of manufactured specimens was analysed with the aim of finding the optimal weight percentage of hemp flour to improve their mechanical performances.
The experimentation performed leads to several conclusions and interesting future developments. It was found that 3% is the best-weighted percentage of hemp flour to increase the mechanical properties of examined mortars made of standardised sand. As further developments, there is a need to identify the limit percentage of hemp flour to be added to the mixture, so as to avoid the decay of the mechanical properties. In addition, further experiments must be carried out on concretes, where the presence of gravel leads to improve the stability and mechanical resistance of the cement matrix.
October 15, 2020
- September 25, 2020
- September 24, 2020
- September 24, 2020
- September 14, 2020
- August 19, 2020
- August 06, 2020
This paper proposed a Small Buckling-Restrained Brace (SBRB) for the ductile truss moment frames and is called here as the Double Braced Truss Moment Frames (DB-TMF). The braces are located at the edge of the truss girder and are only placed around the building perimeter. The braces work in pair as a weak element (structural fuses) and is expected to effectively absorb the seismic energy. The proposed DB-TMF system is an extended development of the Knee Braced Truss Moment Frames (KB-TMF). The DB-TMF system is expected to carry the whole seismic loads, while the rest of the frame is designed to carry only the gravity loads.
To study the performance of the proposed DB-TMF system, non-linear finite element analysis was carried out using the DRAIN-2DX package. From the analysis with various time history records, it was found that the drift ratio of the DB-TMF system is lower than the allowed story drift. The roof-top displacement shows an asymptotic behavior. The shape of the hysteresis curve tends to have a pinching shape. However, the cumulative ductility of the proposed system satisfies the requirements as a hysteretic structure. In the event of an earthquake, only the SBRB and the chords adjacent to the column element are damaged while the rest of the structural elements remain elastic which is expected.
Results and Conclusion:
Based on the performance evaluation of the DB-TMF system, the DB-TMF system is suitable for moderate seismic region and has smaller dimension steel sections compared to the KB-TMF system.
February 28, 2019
- November 15, 2019
- December 20, 2019
- February 28, 2019
- December 28, 2017
- August 25, 2017
- July 31, 2017