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Miscellaneous steel
Published in Gary Anglin, Introduction to Estimating, Plan Reading and Construction Techniques, 2019
A basic decision concerning the posts for handrails is whether they are going to be sunk into concrete or surface mounted with a metal plate and bolted down. Section E, which illustrates a collection of rails and balusters, shows the difference in construction between the two, with a plate bolted on top of the concrete shown on the left. To set the post on the right, the sidewalk has been “core bored”, which means a round hole has been cut into it slightly larger than the post, drilled by a core bore machine operated by one person. After the post is positioned in the sidewalk opening, non-shrink grout is placed between the post and concrete.
Seismic Retrofit of Pilotis Buildings by Novel Aluminium Buckling-Restrained Braces (Al-BRBs). Application to a Modernist Architecture Building in Lisbon
Published in International Journal of Architectural Heritage, 2023
Jorge M. Proença, Ricardo Ferreira, António Sousa Gago
Avci-Karatas and Celik (2013) presented the experimental tests of two Al-BRBs, both with A5083-H111 alloy plate for the core brace, square tube as the external casings and high-strength, non-shrink, grout infill material. These two specimens differed only in terms of the end connection details, one of which welded and the other bolted. The experimental tests showed that the welded end connection detail proved detrimental to the low-cycle fatigue performance, leading to early fracture in the heat-affected zone. In contrast, the bolted end connection detail led to satisfactory performance, with stable, repeatable, hysteretic behaviour and significant cumulative energy dissipation. Later on, Avci-Karatas, Celik, and Yalcin (2018) compared the former test results with those of two equivalent steel core brace BRBs, one with S235JR and the other with S355JR steel core brace. The bolted end connection detail Al-BRB hysteresis loops were found acceptable when compared with those of the steel BRBs, albeit with reduced dissipated energy because of lower cyclic ductility. Nevertheless, the authors recommend weld-free Al-BRBs in buildings or bridges in which severe corrosion effects are expected.
Field investigation of ultra-high performance concrete shear key in an adjacent box-girder bridge
Published in Structure and Infrastructure Engineering, 2019
Husam H. Hussein, Shad M. Sargand, Issam Khoury
Past research focused on three relevant parameters -different levels of TPT force, shear key configurations, and types of grout material- which may enhance shear key performance in adjacent box-girder bridges. Huckelbridge et al. (1995) monitored relative girder displacements of five different adjacent box-girder bridges subjected to truck loading. The shear keys presumably fractured with relative displacement between 0.08 mm and 0.5 mm (0.0032 to 0.0196 in). Based on a finite element investigation and a field study, the authors recommend the relative displacement between adjacent girders should not exceed 0.0254 mm (0.0010 in). Huckelbridge and El-Esnawi (1997) studied the performance of the partial and mid-depth longitudinal joints between adjacent pre-stressed concrete box girders without applying TPT force. The observed load capacity of the mid-depth shear key was 2.4 times that of the partial shear-key design with non-shrink grout. However, high relative displacements across the joints caused all the shear keys to be fractured.
Experimental Study on Seismically Resilient Two-Span Bridge Models Designed for Disassembly
Published in Journal of Earthquake Engineering, 2019
Sebastian Varela, M. Saiid Saiidi
The assembly of the bridge model consisted on several steps as outlined in Fig. 5. Two overhead cranes with lift capacity of 66 kips each were used to safely lift and handle the bridge model components in the laboratory. First, a 3 in.-thick non-shrink grout pad was cast below the footings, and, once it hardened, the footings were rigidly attached to the shake-tables with post-tensioned threaded rods. The top footing surfaces, dowels, and couplers were cleaned and dusted with compressed air, and the SMA bars were fastened to the coupling nuts. Then, the plastic hinge elements were lowered onto the SMA bars, and aluminum shims were tightly driven into the free space around the SMA bars in the EPHs. Hand-tight nuts were attached to the top of the SMA bars, and the column pockets were filled with an appropriate number of thin circular plates to ensure that the SMA bars would engage in compression. The columns were lowered, and, after passing the protruding mild-steel bars through the outer holes in the top steel plate, the columns were set on the plastic hinge elements, and the nuts were fastened to the steel bars completing the column assembly. Further information about the column assembly procedure can be found in Varela and Saiidi [2016a, 2016b, 2016c].