Manhattan West: Converting Site Challenges into Design Opportunities

As cities worldwide are increasing in density, building departments and municipalities are allowing construction using the air‐rights above transportation infrastructure to maximize use of valuable real estate. One Manhattan West (1MW) and Two Manhattan West (2MW) are supertall office towers recently designed and engineered by Skidmore, Owings & Merrill (SOM) that rise above the underground train approach to New York City’s Penn Station. Although the towers are neighbors and have a similar program, they are undercut by the train tracks in different ways. The disparate below ground conditions result in two distinct structural solutions.The structural system of 1MW is a concrete core and a perimeter steel moment frame. The site conditions prevent the perimeter of the 304‐meter‐tall tower from reaching the foundation. This challenge is addressed by transferring the perimeter to the core above the ground, thus making 1MW one of the slenderest structures in New York City. The structural system of 2MW consists of a central braced steel core with outrigger and belt trusses and a perimeter steel moment frame. Here the perimeter reaches the foundation with a few lateral transfers however only half of the core reaches terra firma. This paper presents a side‐by‐side comparison of the structural solutions for the two towers.

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MACRO-ELEMENT MODEL OF A STEEL MOMENT FRAME SUBJECTED TO FIRE-INDUCED COLUMN LOSS

Applications of Structural Fire Engineering ◽

10.14311/asfe.2015.007 ◽

2016 ◽

Author(s):

Ha Nguyen ◽

Ann E. Jeffers ◽

Venkatesh Kodur

Keyword(s):

Progressive Collapse ◽

Experimental Tests ◽

Element Model ◽

Fe Model ◽

Structural System ◽

Moment Frame ◽

Moment Connections ◽

Steel Moment Frame ◽

Collapse Mechanisms ◽

Macro Element

A progressive collapse mitigation strategy is to ensure load redistribution when a column fails due to fire. The study seeks to understand whether welded unreinforced flange-bolted web (WUF-B) moment connections can effectively redistribute loads in a structural system subjected to fire when a critical column is lost. A component (or macro-element) model was derived to simulate the WUF-B connection and validated against experimental tests and high-resolution finite element (FE) models of subassemblies at room temperature and at elevated temperature. The component model was then utilized in a 2D macro FE model of a ten-story steel-framed building subjected to the loss of a column during long fire exposure. This paper presents the collapse mechanisms and quantifies structural performance based on acceptance criteria. A parametric study on location of column loss and fire occurrence is also included.

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Precast Core Wall System for High-Rise Buildings

IABSE Congress, New York, New York 2019: The Evolving Metropolis ◽

10.2749/newyork.2019.0110 ◽

2019 ◽

Author(s):

Juan E. Carrion ◽

William F. Baker ◽

Charles Besjak

Keyword(s):

New York ◽

Precast Concrete ◽

Concrete Strength ◽

Attractive Alternative ◽

Lateral Loads ◽

Concrete Core ◽

High Rise ◽

The Core ◽

Steel Shapes ◽

Wall System

The design of high-rise buildings is usually governed by lateral forces (e.g., wind or seismic). One of the most efficient structural systems to resist lateral loads is the core wall system. Traditionally high-rise concrete cores have been constructed using cast-in-place concrete, however precast systems offer an attractive alternative to cast-in-place construction. A precast concrete core wall system has been developed for high-rise buildings and will be presented in this paper. The main components of the system are the core walls, which are composed of multiple precast panels. The panel layout is determined based on the geometry of the tower and the capacity of the transportation and lifting equipment, while the wall thickness, concrete strength, and reinforcement are determined to satisfy strength and serviceability requirements. Several methods for connecting the panels have been developed, including combinations of embedded steel shapes, bolts, welds, and continuous reinforcing bars or post-tensioning. An application of the system to a 296 m (972 feet) tower in New York City is presented in this paper. This application demonstrates that the precast core wall system is an attractive and viable alternative to cast-in-place construction, capable of resisting the large forces associated with high-rise buildings, and with several advantages, including speed of erection, cost, as well as the high quality of precast concrete.

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Seismic Performance of a Green Roof Structure

Sustainability ◽

10.3390/su13084278 ◽

2021 ◽

Vol 13 (8) ◽

pp. 4278

Author(s):

Svetlana Tam ◽

Jenna Wong

Keyword(s):

Green Roof ◽

Time History ◽

Green Roofs ◽

Moment Frame ◽

Steel Moment Frame ◽

Roof Structure ◽

Nonlinear Time History Analyses ◽

Vegetated Roofs ◽

Nonlinear Time History ◽

The Impact

Sustainability addresses the need to reduce the structure’s impact on the environment but does not reduce the environment’s impact on the structure. To explore this relationship, this study focuses on quantifying the impact of green roofs or vegetated roofs on seismic responses such as story displacements, interstory drifts, and floor level accelerations. Using an archetype three-story steel moment frame, nonlinear time history analyses are conducted in OpenSees for a shallow and deep green roof using a suite of ground motions from various distances from the fault to identify key trends and sensitivities in response.

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