Masonry columns

Pb Distance between layers of bars in the confinement of masonry columns Pf Spacing of FRP strips or discontinuous FRP U-wraps tf Thickness of FRP laminate... 

In the preliminary stage of the drawing up of the reinforcement plan, besides the evaluation of the mechanical properties of the members making up the structure, tests for the mechanical properties of the substrate should also be performed. The higher or lower incidence of the substrate characteristics is a function of the kind of application that is to be used either with reference to adherence applications (bending or shear reinforcement) or contact applications (passive confinement of masonry columns or pillars). In order to increase the mechanical properties of the substrate, it is possible to intervene in advance and apply composite materials by laying a suitable primer using special products. 

Displaced drums in rows of masonry columns (Fig. Ih) are products of either in-plane or out-of-plane seismic loads. Both shifting and rotation of drums occur. Historically, the observation of aligned, fallen monolithic columns has been used to infer directions of earthquake epicenters. However, this interpretation is erroneous, since column alignment in fallen strucmres can also be produced by heavy storms acting on deteriorated buildings (Ambraseys 2006). 

Measures to reduce the impact of fire include active and passive systems. Active systems include automatic sprinkler, water deluge, water mist, gaseous agent, dry chemical, foam, and standpipe handle systems. Passive protection is provided by fire resistive construction, including spray-applied or cementitious fireproofing of steel, concrete/masonry construction, and water-filled steel columns. Chapter 7 provides details on the design of fire protection systems. 

Figure 11.10. Four examples of masonry patterns and their symmetries. Column A shows the patterns B shows the correct or incorrect choices of lattice vectors and unit cells C shows the symmetry elements.

In the manufacture of sulfuric acid, the SO2 is first catalytically oxidized, to SO3 which is then absorbed into a H2SO4-H2O-SO3 solution (absorption directly into H2O is not feasible because a mist forms with SO3 that cannot be absorbed). An absorption tower is usually composed of various kinds of packing, but sometimes trays are used as in a distillation column. For sulfuric acid manufacture the steel tower is lined with acid proof masonry, and chemical stoneware is used for the packing. A tower might be 7 or 8 m in diameter and absorb 1,000 tons per day of SO3. Absorption towers are used to retrieve many other gases from the vapor phase into the liquid phase (not necessarily water). 

Biological columns are large-sized concrete or masonry structures, usually round with a gridded base. They are filled with filtration packing through which treated wastewater flows downstream (Fig. 4.25). 

Pier- A column of masonry, usually rectangular in horizontal cross section, used to support other structural members. Also see Caisson. 

B6595 is a concrete masonry unit (CMU) structure with a concrete-reinforced column and steel joist frame on a concrete slab and a built-up flat roof. The building is used to store non-radioactive materials and supplies that are used in the HCF. 

In old buildings timber often fails where it enters a masonry wall or in roofs at the junction of rafter and tie beam where the truss is supported on the wall plate. In both cases leaking water over a long period has resulted in wet rot. The repair process consists of replacing the decayed timber with reinforced epoxy mortar. The reinforcement may consist of steel plate or bars which are drilled or set deep into the sound portion of the timber to ensure a good bond and load transfer. Fig. 6.23 shows bonded dowel bars used to repair the end section of a column or beam while Fig. 6.24 illustrates a typical repair to a roof truss. 

The church is designed as a massive masonry stmcture constracted of different types of stone in cement lime mortar (PS state). The main structural elements are the domes, the arches, the vaults, the wooden floor structures, the columns, the walls and the foundation. In order to decide on the mix design for the cement lime mortar based on the analysis of the church, three options have been adopted for it ... 

ElGawady M, Endeshaw M, McLean D, Sack R (2010) Retrofitting of rectangular columns with deficient lap splices. ASCE J Compos Constr 14(l) 22-35 EN 1015-11 (1993) Methods of test for mortar for masonry - Part 11 Determination of flexural and compressive strength of hardened mortar. European Committee for Standardization. Brassels... 

Park S, Mosalam KM (2012) Parameters for shear strength prediction of exterior beam-column joints without transverse reinforcement. Eng Struct 36 198-209 Paulay T, Priestley MJN (1992) Seismic design of reinforced concrete and masonry buildings. Wiley, New York, pp 250-303... 

Plastic composites are found to be effective in retrofitting masonry buildings to reduce seismic damage to remove seismic deficiency the thin layer of reinforcement (fibre reinforced composite sheet) applied to the wall (like wall paper) is shown to increase substantially the load carrying capacities of masonry walls [38] as well as of reinforced concrete structures, including columns and walls and beam-column joints [39]. 

Shear failure of the so called shear columns, typically those in staircases or due to the presence of strip windows with strong infill masonry... 

Within the field of masonry member reinforcement, the use of composite materials for columns confinement is very interesting. Such intervention is aimed at increasing their resistance and ultimate deformation. Moreover, the same intervention can improve the structural response under working conditions. 

The structural masonry member confinement should be carried out with the help of fabrics, sheets, and bars (otherwise called ground anchors) of composite material. Fabrics are applied on the contour as external continuous wrapping or discontinuous wrapping the bars are arranged inside the column, in order to realize suitably widespread reinforced stitches. 

As in the case of concrete columns, the confinement of masonry circular section columns allows to obtain a considerable enhancement of compression resistance compared to the smaller ones that can be obtained in the case of squared or rectangular sections. As for circular sections, the horizontal efficiency coefficient, kn, related to the external binding, is equal to 1, whereas the vertical efficiency coefficient, ky, is equal to 1 in the case of a continuous binding. 

The European standard EC8-3 (CEN 2005) defines three Umit states, i.e. Umit states of damage limitation (DL), of significant damage (SD), and of near collapse (NC). The limit states are defined at the element level by the rotations in the moment - rotation relationship of the plastic hinge. In test examples presented in this paper only the probability of the exceedance of the NC limit state was evaluated. The NC limit state at the element level is reached when the rotation in plastic hinge exceeds the ultimate rotation, which corresponds to a 20% drop in strength. At the structure level, there is a lack of definitions of the limit states in codes. In this study, it has been conservatively assumed that the most critical column controls the state of the structure. Consequently, the structure is assumed to attain the NC limit state when the first column attains the NC limit state. Furthermore, it has been conservatively assumed that the NC limit state corresponds to the failure of the structure. The collapse of masonry infills does not influence the NC limit state. 

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