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Force-System Resultants and Equilibrium
Published in Richard C. Dorf, The Engineering Handbook, 2018
A column is an initially straight load-carrying member that is subjected to a compressive axial load. The failure of a column in compression is different from one loaded in tension. Under compression, a column can deform laterally or buckle, and this deflection can become excessive. The buckling of columns is a major cause of failure. To illustrate the fundamental aspects of the buckling of long, straight, prismatic bars, consider a thin meter stick. If a tensile axial load is applied to the meter stick, the stable equilibrium position is that of a straight line. If the stick is given a momentary side load to cause a lateral deflection, upon its release the stick immediately returns to the straight line configuration. If a compressive axial load is applied, a different result may occur. At small axial loads, the meter stick will again return to a straight line configuration after being displaced laterally. At larger loads the meter stick will remain in the displaced position. With an attempt to increase the axial load acting on the buckled column, the lateral deformations become excessive and failure occurs.
Palazzo Lavoro
Published in Clifton Fordham, Constructing Building Enclosures, 2020
Ranks of elements that could be read as columns would have suggested that, perhaps, the roof was supported by this perimeter, rather than being cantilevered from the mushroom piers within. The curved shape, however, presents far too thin a cross section at its ends to carry such loads. A fundamental difference between a column and a beam, after all, is that the axial load on a column is consistent throughout its length, while the bending load on a beam varies with distance from the support. Tapering these braces eliminates the possibility of their carrying a bearing load, leaving only the lateral bracing function as a possible interpretation.
Introduction
Published in Sing-Ping Chiew, Yan-Qing Cai, Design of High Strength Steel Reinforced Concrete Columns, 2018
Composite columns are classified into two principal categories: (1) steel-reinforced concrete sections and (2) concrete-filled hollow steel sections. Typical composite cross-sections of SRC columns are shown in Figure 1.1. In fully encased sections, the steel section is embedded within concrete, as shown in Figure 1.1a. Partially encased sections consist of steel I- or H-sections and the concrete filled in the void between the steel flanges, as shown in Figure 1.1b and c.
Optimisation of life-of-mine production scheduling for block-caving mines under mineral resource and material mixing uncertainty
Published in International Journal of Mining, Reclamation and Environment, 2022
Roberto Noriega, Yashar Pourrahimian, Eugene Ben-Awuah
Production scheduling is carried out over a 10 year horizon, in this particular case selected to be able to experiment extensively, however could be extended for longer periods to cover the life-of-mine. The production unit dimensions for aggregating resource blocks into columns are set at 20 m by 30 m to represent column extraction units in caving mines. The maximum column height is set at 300 m with a minimum column height of 60 m. These guarantee that if the optimisation model decides to open up a production unit at the undercut level, it will draw material from it until at least a height of 60 m and up to 300 m with the capability of stopping anywhere in between. The maximum adjacent relative height of draw, which represents the difference in the height of draw between a given PU and its adjacent ones, is set to 60 m. The selected PU dimensions provide a cave back slope of between 60° to 70°. The minimum draw rate per column is set to 70 kton/period, which is equivalent to a draw height of 30 m, with a maximum draw rate of 140 kton/period equivalent to a 60 m draw height. These parameters would be adjusted to reflect a given project’s geotechnical environment to guarantee good flow conditions for the broken ore. Based on these dimensions, the case study comprises 108 PU, representing drawpoints, and 864 MU representing slices to be extracted. The maximum undercutting rate is set at 9600 m2/period, which restricts the amount of PU and undercut area that can be developed in any given period.
Full-scale Experimental and Numerical Investigations on Seismic Performance of Square RC Frame Columns with Hollow Sections
Published in Journal of Earthquake Engineering, 2022
Cantian Yang, Linlin Xie, Aiqun Li
In view of the aforementioned findings, a new type of square RC column with a square cavity is proposed, and spiral stirrups are adopted at four corners of the section, as shown in Fig. 3. The notable characteristics of this column are as follows. (1) The spiral stirrups at four corners of the section are expected to have a strong confinement effect on the corner concrete and effectively ensure the seismic performance of the column. (2) Longitudinal reinforcements at the four corners are set within the confined region of the spiral stirrups. The other longitudinal reinforcements are set at the edge of the column, similar to the case of solid RC columns. These reinforcements are intended to increase the load-bearing capacity of the column. (3) Rectangular stirrups are adopted to ensure the shear strength. (4) The stirrup scheme and arrangement are simple and will not lead to manufacturing difficulties.