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The Winds of Change
Published in Frank R. Spellman, The Science of Wind Power, 2022
Basically, there are five common types of tower foundations presently used for onshore wind towers, including the shallow mat extension, the ribbed beam basement, the underneath piled foundation, the uplift anchors, and the so-called new type.
Transmission Line Structures
Published in Leonard L. Grigsby, and Distribution: The Electric Power Engineering Handbook, 2018
Robert E. Nickerson, Peter M. Kandaris, Anthony M. DiGioia
Spread footings (cast-in-place concrete, precast concrete, grillages, pressed plates) provide basic resistance to axial forces (uplift and compression), while considering the load orientation (inclination and eccentricity) of the applied loads. Foundations must be designed to prevent shear failure and excess settlement in compression and have adequate size and depth to prevent uplift failure or excessive lift of foundation legs. The IEEE/ASCE foundation design guide (Tedesco and DiGioia, 1983; DiGioia, 2002) offers a number of models for spread footings using traditional design methods. AASHTO LRFD Bridge Design Specifications (AASHTO, 2010, Section 10.6) give detailed design methods for RBD of spread footings. Spread footings are most commonly used with lattice tower structures and as central bearing foundations for guyed lattice tower structures.
Optimised design of wind turbine gravity foundations
Published in Alphose Zingoni, Insights and Innovations in Structural Engineering, Mechanics and Computation, 2016
The foundation design process involves two relatively independent but related design processes viz. the behaviour and capacity of the soil in response to the structural loading, and the subsequent design of the concrete element that comprises the base and transfers the loadings from the tower to the soil.
Development and Validation of Empirical Formulations for Predicting the Frequency of Historic Masonry Towers
Published in International Journal of Architectural Heritage, 2023
Francesco Testa, Alberto Barontini, Paulo B. Lourenço
The analysis of the information of the towers belonging to the training set (Table 1) reveals that the total height ranges between 7.2 m (the Squat Masonry Tower of the Trani Castle) and 112.0 m (the Torrazzo in Cremona), the minimum side length varies from 3.0 m (the Bell Tower of S. Giorgio Church in Trignano) to 14.5 m (the Giotto Bell Tower), and the thickness of the base masonry walls from 0.4 m (the Bell Tower of S. Giorgio Church in Trignano) to 4.0 m (the Bell Tower of St Maria del Carmine Church). Moreover, the aspect ratio is found to range between 1.7 (the Squat Masonry Tower of the Trani Castle) and 12.6 (the Torre del Mangia). The value of the first natural frequency is plotted against the total height of the towers, in Figure 4, where a colour map is included to show different aspect ratios. The fundamental frequencies range from 0.33 Hz (the Asinelli Tower) to 7.50 Hz (the Squat Masonry Tower of the Trani Castle), presenting a clear inverse non-linear trend for increasing values of the height. A similar trend appears for increasing values of the effective height (Figure 5), suggesting a likely good fitting with a power regression. The correlation between the first natural frequency and the other geometrical features (minimum and maximum side length and wall thickness), as illustrated in Figure 5, is poorer, presenting a slightly similar non-linear inverse trend, but with larger scatter of the data.
The influence of newly built high-rise buildings on visual impact assessment of historic urban landscapes: a case study of Xi’an Bell Tower
Published in Journal of Asian Architecture and Building Engineering, 2022
Xixiao Bu, Xi Chen, Shiqi Wang, Yuping Yuan, Chenping Han
For many cities, the historic Bell Tower is a remarkable architectonic element and urban icon (Nisticò et al. 2016). For the purpose of preserving the aesthetic values of these historic buildings, tough restrictions are implemented upon the construction and reconstruction of the surrounding buildings. The urban planning usually sets up a height restriction on the modern buildings around the historic buildings under key protection. In Xi’an, the Regulations on Restricting the Height of Buildings in Urban Area enacted in 1980 explicitly stipulates that the Xi’an Bell Tower is under key protection. Accordingly, the height of surrounding buildings should be regulated in accordance with the protection range and actual situation. Since the height of Xi’an Bell Tower is 36 m above the ground, the height of surrounding buildings inside the City Wall is set at eight height levels: 36, 28, 24, 21, 18, 15, 12, and 9 m. As for which height level a building should be at, it is decided by its distance to the Bell Tower. To be specific, the closer a building is to the Bell Tower, the lower it is to be built. The height of buildings closest to the Bell Tower is no higher than 9 m. The plane distance between each height level is about 50–60 m. A small number of high-rise buildings can be designed within the area where high-rise buildings are feasible. According to the statistics, the buildings centering around the Bell Tower are no higher than the Tower. For example, the height of Bell Tower Restaurant is 31 m, while both Posts and Telecommunications Plaza and Kaiyuan Shopping Mall are 32 m high.
Highlighting the Impact of the Construction History of a Cultural Heritage Building Through a Vibration-Based Finite Element Model Updated by Particle Swarm Algorithm
Published in International Journal of Architectural Heritage, 2023
Arnaud Montabert, E. Diego Mercerat, Hélène Lyon-Caen, Maria Lancieri
In particular, the stratigraphic analysis delineated the building phases by identifying the construction techniques used during different periods. 12 building phases were identified, claiming an asynchronous architectural evolution in geometry and material used. The main building phases are summarized below. Evidence point to the church’s existence at least since the 10th century. In the 15th century, the building was only composed of the nave and the central apse (phases 1, 2, and 3 in Figure 1). During this century, the two side chapels were successively added (initial phase 3 of the lateral chapels in brown in Figure 1), followed by the bell tower in a final stage (phase 4 of the bell tower in orange in Figure 1b-d). Phases 5 and 6 are related to minor renovations. The opening of a door in the east-facing wall of the bell tower in 1497 and the repair of the three windows of the southern wall of the nave correspond to phase 5. The rose window of the facade was repaired during phase 6 and is no longer there. The earthquake of June 6, 1542 (estimated macroseismic Mmw 6.0, Rovida et al. 2016) induced much damage. The upper part of the bell tower collapsed, and cracks opened in the west and east wall of the bell tower throughout the total height. Only the south wall of the bell tower was rebuilt to its original height, changing the bell tower to a vertical L-shape tower (the rebuilt phase 7 of the bell tower is shown in green in Figure 1b-d, the L-shape at that time consisted of the orange and green parts). The outer side of the facade, the north wall, and the south wall of the nave are still tilted. The two lateral chapels collapsed and are nowadays rebuilt using a different building technique (the rebuilt phase is shown in green in the two lateral chapels in Figure 1d). Phase 8 is related to minor repairs like filling openings in the nave or cracks in the bell tower. The earthquake of September 8, 1611 (estimated Mmw 5.1) induced several cracks in the L-shape bell tower and weakened the upper part leading the bell tower to its current shape after a deep reconstruction (phase 9 shown in blue in Figure 1b-d). The 1919 earthquake (Mmw 6.4) did not induce any damage, probably due to its greater epicentral distance. The door opened in the bell tower during phase 5 and was closed in phase 10. The arc of the central apse was raised about 1.20 m during phase 11. The rose window was filled in during phase 12. The final phase, 13, is related to all the restoration events during the 19th century.