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Introduction to Benchmark Control Problems
Published in Suhasini Madhekar, Vasant Matsagar, Passive Vibration Control of Structures, 2022
Suhasini Madhekar, Vasant Matsagar
The column lines employ three-tier construction, i.e., monolithic column pieces are connected at every three levels beginning with the first level. Column splices, which are seismic (tension) splices to carry bending moment and uplift forces, are located on the 1st, 4th, 7th, 10th, 13th, 16th, and 18th levels at 1.83 m above the centerline of the beam-column joint. The column bases are modeled as pinned and are secured to the ground at the B-2 level. RC foundation walls and surrounding soil are assumed to restrain the structure at the ground level from horizontal displacement. The floor system comprises 248-MPa steel wide-flange beams acting compositely with the floor slab. Each frame resists 50% of the seismic mass associated with the entire structure. The seismic mass of the structure is due to the steel framing, floor slabs, ceiling/flooring, mechanical/electrical, partitions, roofing, and a penthouse located on the roof. The plan of the 20-story N-S moment-resisting frame is depicted in Figure 11.6(a) and the elevation in Figure 11.6(b).
Applications of approximate methods in geo-engineering problems
Published in Ömer Aydan, Continuum and Computational Mechanics for Geomechanical Engineers, 2021
The stability of rock slopes against flexural toppling was formulated by Aydan and Kawamoto (1987, 1992). This was the first time for mathematical treatment of this instability mode under static and dynamic conditions with/without reinforcement. To investigate the effect of rockbolting, it is assumed that two layers inclined at various angles with respect to horizontal are subjected to a gravitational force field (Figure 9.45a) and material properties given in Table 9.15 were utilized in computations and the thin-band element (Aydan 1989; Aydan et al. 1990; Appendix 6) was used to simulate the interface behavior. Four different case studies were made to see the differences between the various bolting patterns (Figure 9.45b). Figure 9.46a-1 and a-2 show the fiber stress distributions at the base of the layers for four different cases for two inclinations 45° and 75°. It is also quite interesting to note that there is no interaction between two layers of the same height implying that no load is transferred to the lower layer from the upper layer. As noted from the figures, the behavior of a multi-layered column approaches that of a monolithic column of equivalent thickness through rockbolting.
Reinforcement and support of rock slopes
Published in Xia-Ting Feng, Ömer Aydan, Rock Reinforcement and Rock Support, 2018
To investigate the effect of rockbolting, it is assumed that two layers inclined at various angles with respect to the horizontal are subjected to a gravitational force field (Fig. 8.12a), and material properties given in Table 8.1 were utilized in computations. Four different case studies were made to see the differences among the various bolting patterns (Fig. 8.12b). Figures 8.12c-1 and c-2 show the fiber stress distributions at the base of the layers for four different cases for two inclinations (45° and 75°). As noted from the figures, the behavior of multi-layered column approaches that of a monolithic column of equivalent thickness through rockbolting. Figure 8.12d-1, d-2, e-1, and e-2 show the shear stresses in bolts at the discontinuity plane and the axial stress distributions in the bolts, respectively. The distribution of stresses in bolts differs depending upon the location. It is expected that the reinforcement offered by rockbolts by thickening the layers should also be effective against the buckling failure of rock slopes.
A novel erection technique of the L-shaped precast frames utilizing laminated metal plates
Published in Journal of Asian Architecture and Building Engineering, 2021
A significant number of experimental and numerical studies have been performed to examine the behavior of extended endplate connections for steel structures that were subjected to monotonic and cyclic loads (Tahir and Hussein 2008; Mureşan and Bâlc 2017; Ismail et al. 2016; Sumner and Murray 2002; Sofias, Kalfas, and Pachoumis 2014). These studies showed that steel connections can act as either fully rigid or semi-rigid connections, depending on the endplate thickness, bolt diameter, number of bolt rows and columns, bolt spacing, bolt grade, stiffeners, column and beam sizes, and yield strength of the steel. In this study, mechanical joints with fully restrained moment connections (which were developed to provide rapid and facile connections for composite precast columns) were employed. Here, a pair of steel plates was connected, offering monolithic column joints. Extensive full-scale assembly testing of the large columns that were designed to resist gravity and lateral loads, was performed to investigate how efficiently the vertical columns can form monolithic joints. The observed time required for this assembly using mechanical joints was less than 30 min. The proposed method can be used as an alternative for modular offsite construction for buildings and industrial plants subjected to heavy loads, thereby reducing the cost of construction compared to using steel structures.
Nonlinear finite element analysis of mechanical connections splicing precast columns with stiffened laminated metal plates
Published in Journal of Asian Architecture and Building Engineering, 2020
A benchmark experimental investigation was performed to explore the influence of column connections on the flexural capacity of the column in the study of Hu, Hong, and Park (2017) in which seven test specimens were manufactured and tested. Hu, Hong, and Park (2017) investigated the structural performance of a column connection stiffened with internal bolts and ribs. Table 1 (Hu, Hong, and Park 2017; Nzabonimpa and Hong 2018) summarizes the material properties of column plates, exterior bolts, rebars and steel columns used in the investigation. As described in the previous study by the authors (Hu, Hong, and Park 2017), a filler plate was not used for Specimen C2, in which nuts were threaded onto the rebars from the columns in the pits of the column plates. Nuts were also located in the counterbores of the column plates, and column plates were thick enough to completely accommodate the nuts. The column plates of Specimen C2, with a thickness of 45 mm, did not display any noticeable plate deformation. However, the column plates of Specimen C5, with thickness of 20 mm, were deformed. Specimen C6 was a steel-concrete composite column that was fabricated as a monolithic column. In Specimen C7, columns were spliced with high-yield-strength plates (Fy = 650 MPa) to explore the influence of high-yield-strength mechanical joint plates on the lateral flexural strength.
PolyHIPEs for Separations and Chemical Transformations: A Review
Published in Solvent Extraction and Ion Exchange, 2019
Kathryn M. L. Taylor-Pashow, Julia G. Pribyl
In work by Yao et al., a series of glycidyl methacrylate-based polyHIPE monoliths were prepared using the tri-block copolymer Pluronic F127 (PF127) as the surfactant.[29] Due to the ability of this surfactant to direct supramolecular self-assembly, a wide range of morphologies could be obtained by altering the PF127 concentration in the emulsion. The glycidyl methacrylate-based monoliths obtained had sub-micron skeletons, micrometer-sized through-pores, and relatively large specific surface areas, resulting in excellent permeability. Based on these characteristics the monoliths were shown to be excellent materials for fast and high-throughput separation of proteins after functionalization with diethylamine similar to the work in the preceding paragraph. The same triblock copolymer (PF127) was also used for preparation of a polyHIPE material using a vinyl ester as the monomer with ethylene glycol dimethacrylate as the crosslinker.[30] In this work, the HIPE was charged into a stainless-steel column to serve as the mold for preparing the monolithic column. A high-performance liquid chromatography (HPLC) system was then used for testing of the resultant material. Prior to chromatography experiments, the poly(vinyl ester) monolith was acetylated by reaction with excess acetic acid. Results from the acetylation reaction showed that the average loading of hydroxyl groups was 14.0 mmol/g. HPLC experiments indicated that immunoglobulin could be separated from human plasma and chicken egg yolk with high resolution within 4 minutes. An additional demonstration of fast separation of proteins with this material was the separation of two proteins (interleukin-18 and Lys) within two minutes at a rate of 1445 cm/h.