May 2001 – Fine-tuning seismic design to achieve savings – the Lakepoint Tower project.

April 2001 – M+L champions the use of environmentally friendly concrete for The GAP Headquarters building in San Francisco.

Fine-tuning seismic design to achieve savings – the Lakepoint Tower project.

(May 2001) One of Middlebrook + Louie’s latest design projects, Lakepoint Tower, is a 30-story building with 3 levels of underground parking and 723,000-gsf of office space. The building site, near Oakland’s Lake Merritt, is located within 3 miles of the Hayward seismic fault.

The near-fault location of Lakepoint Tower increases the challenge to the design team. Recent earthquakes such as the 1994 Northridge Earthquake, resulted in various revisions to the 1997 version of the Uniform Building Code (UBC). Among the most important changes in the new UBC are additional design requirements for structures located near earthquake faults. The direct result is an appreciable increase in the quantity of structural steel required for new buildings like Lakepoint Tower.

However, a more sophisticated alternative to the seismic design of structures, Time/History analysis, can be used to meet the 1997 UBC requirements. This alternative allows engineers to fine-tune the seismic performance of a particular structure by studying how it will behave under a variety of seismic event scenarios. By using this approach, the structural engineers at Middlebrook + Louie aim to achieve a more economical, refined design which reduces the quantity of structural steel required, without sacrificing (building) performance.

Simulations of 7 different seismic events, each with characteristics of seismic excitation deemed possible at the Lakepoint Tower site, are being evaluated on a computer model of the tower’s structure. The simulations will produce numerical output related to the building’s performance and the site’s soil conditions in terms of seismic forces and displacements. Then, through iterative timing of the seismic force resisting system, Middlebrook + Louie engineers will optimize the sizes of the structural system’s individual components.

By using Time/History studies for Lakepoint Tower, M+L engineers can provide value for the project by reducing steel tonnage and construction costs. The extra engineering effort can reduce costs not just in terms of immediate economics, but also in the environmental impact associated with steel production.

To contact Middlebrook + Louie about our full range of design and consulting services, click here.

Middlebrook + Louie champions the use of environmentally friendly concrete for The GAP Headquarters building in San Francisco.

(April, 2001) As GAP employees move into their new headquarters building on San Francisco’s scenic Embarcadero waterfront, they may be unaware of some of the trend-setting environmental features of their new 15-story building.

Chief among these is the use of a special concrete technology called High Volume Fly Ash Concrete. The GAP building is the first of its kind in San Francisco to use this environmentally friendly structural material.

What is High Volume Fly Ash Concrete (HVFAC)? Well, fly ash is a microscopic waste byproduct of power generation plants, but has been found to have cement-like properties under certain conditions. HVFAC substitutes large quantities of this fly ash for much of the portland cement normally used in concrete.

The environmental benefits of this substitution are two-fold. First, since experts have linked the production of portland cement to about 8 percent of the world's carbon dioxide emissions, the significantly reduced quantities of portland cement in HVFAC directly translate into a reduction in CO2 pollution. And, since roughly 50 million tons of fly ash makes its way to landfills each year, diverting large quantities of fly ash to produce this new type of concrete can help mitigate the demands on our already burdened landfills.

Working with experts from the University of California at Berkeley, Middlebrook + Louie convinced the GAP Headquarters design and construction team to opt for HVFAC for major portions of the building’s concrete structural systems. Middlebrook + Louie helped demonstrate that HVFAC results in higher quality concrete, with greatly improved durability, crack resistance and many other properties when compared with conventional concrete — enhancing the overall quality of projects like the GAP building.

Environmentally friendly, sustainable design has recently emerged as a key issue in development. Middlebrook + Louie continues to search for economical methods such as HVFAC to produce structures that are in tune with this issue. Championing the choice of HVFAC with clients, designers, contractors and suppliers demonstrates Middlebrook + Louie’s belief that structural engineering can make a positive contribution to our industry’s efforts to improve the global quality of life.

To contact us about more information on HVFAC, click here.