Tuned Liquid Damper (TLD) Controls Motion in Chicago Residential Tower

Reinforced concrete was chosen as the structural system for several important reasons on the Elysian Hotel & Private Residences in Chicago, Ill. The floor-to-floor heights were minimized with the use of thin, post-tensioned concrete slabs, which allowed the owner to cost effectively maximize the number of floors in the building. In addition, concrete provided the necessary stiffness for the outrigger-braced lateral system while providing the speed of construction necessary to meet the project schedule demands.

Wind and its dynamic effects governed the structural design of this 700-foot tall concrete residential tower. Originally conceived as a 40-story tower – its concrete core and outrigger lateral system and structural layouts were established, and then the height was then extended to 61 stories. Recognizing the structure’s stiffness would now not be sufficient to keep accelerations within acceptable limits (the key for lateral design of tall towers) – at least not without increasing costs substantially and yielding impractical architectural space layouts – Halvorson and Partners (HP) sought to economize the structure at hand and introduce a secondary damping system to insure accelerations in the tower due to wind met standard criteria.

A tuned liquid damper (TLD) at the top of the building provided the latest approach to controlling perceptible motion in tall, slender buildings. It offerslow cost, low maintenance and high performance over a broad range of wind conditions. The Elysian is one of the first residential towers in the United States to incorporate this efficient technology. More on the Elysian.

Concrete Rebuilds High School Destroyed By Katrina

Slidell, La., a suburb on the shores of Lake Pontchartrain, was hit particularly hard by the winds and storm surge of Hurricane Katrina. The storm surge pushed more than eight feet of water through the area, all but demolishing Salmen High School. More on Slidell.

Concrete Construction Comes of Age

Originally built and opened in the 1960s, the Bethany Terrace is a health and rehabilitation center that is now adding 45 new assisted living apartments to hold up to 50 percent more residents than the 120 currently living there. The project architect suggested using precast concrete for the addition, called Terrace Gardens Assisted Living, because it is able to give the right look, does not require any variances, and can be placed quickly and cost effectively. More on Bethany Terrace.

Reinforced Concrete Design - Distance Learning Modules
This DVD contains five distance learning modules designed by PCA which include narrated presentations covering analysis and design of reinforced concrete. Fundamentals and theories are explained in detail. Requirements and background of the ACI 318 Building Code are introduced and discussed. For each topic, numerous design examples illustrate the design basics and the application of the Code requirements and limits.

Additionally, each learning module ends with a quiz covering the topics discussed. Upon successful completion of each quiz the user will receive a PCA Certificate of Completion and will be awarded 2.0 or 3.0 Professional Development Hours (equivalent to 0.2 or 0.3 Continuing Education Units in most states).

PCA Notes on ACI 318-08 Building Code Requirements for Structural Concrete with Design Applications
This tenth edition of the classic PCA publication has been updated to reflect code changes introduced in the latest version of Building Code Requirements for Structural Concrete, ACI 318-08, and Commentary, ACI 318R-08. All design examples in this text have been revised to reflect the new notation and terminology, load and strength reduction factors, and the unified design provisions for reinforced and prestressed concrete members under flexure and axial load. An alternative torsion design method is summarized and its application illustrated through an example. Enhanced provisions for the design of anchors are described, and their application is illustrated through several examples.

Additional PCA Concrete Design Resources

ACI/PCA Simplified Design of Reinforced Concrete Buildings of Moderate Size
One-day seminar sponsored jointly by the Portland Cement Association and ACI

Increase your design efficiency and reduce the time it takes to design small to moderate size buildings by applying the design procedures that you will learn at this seminar in accordance with ACI 318-08, IBC 2009, and ASCE 7-05. More information and registration.

Reinforced Concrete Design
Two-day seminar sponsored jointly by the Portland Cement Association and ACI

More information and registration.

The Sustainable Concrete Guide – Strategies and Examples

This comprehensive new resource from the U.S. Green Concrete Council offers specific strategies for the best use of concrete in high-performance, long-lasting, green buildings. Included in the guide are case studies, technical data and references, and numerous practices that can be implemented immediately. It will be of interest to architects, engineers, contractors, and others who work with concrete, as well as environmental professionals who seek the best solutions to today’s environmental challenges. More information and purchase.

Novak Participates in “Ask the Expert” on Sustainable Design

As the keynote speaker of the Chicago Museum of Science and Industry’s City Science teacher workshop, Lawrence Novak, PCA’s director of engineered buildings, presented on sustainability and high-rise design. On May 21, more than 60 educators from the Chicago area attended the workshop. As part of the special events, Novak also participated in the “Ask the Expert” session at the museum. He fielded questions such as “What recommendations can I provide to my school to improve our sustainability?” The resulting discussion included topics such as utilizing pervious pavement for the school parking lots.

spSlab Update Targets Canadian Users

StructurePoint released spSlab v3.11 with changes concerning the Canadian code CSA A23.3-04/94. One of the key issues addressed in this release is a revised interpretation of CSA A23.3 length of attached torsional member (Lt) used in calculations of torsional stiffness (Kt) at exterior supports. Another key revision targets CSA A23.3-04 detailing requirements which results in a reduction of reinforcement placed within b_b band over supports in two-way floor systems.

More about StructurePoint’s reinforced concrete analysis and design software.

Annual Building Professors' Seminar
August 2-4, Skokie, Ill.

In an effort to keep the concrete industry in touch with university professors of civil, structural, and architectural engineering, the Concrete Reinforcing Steel InstituteI, the National Ready Mixed Concrete Association, the Portland Cement Association, the Precast/Prestressed Concrete Institute, and the Post-Tensioning Institute co-sponsor an annual Building Professors' Workshop. Since 1992, the seminar has been held every summer at PCA's Skokie, Ill., headquarters. Sponsored by regional cement and concrete promotion groups, professors from around the U.S. travel to Skokie to attend this three-day workshop. More.

• Design-Build Conference and Expo
October 18-20, Las Vegas, Nev.

• ACI Fall Convention
October 24 – 28, Pittsburgh, Pa.

• GreenBuild International Conference and Expo
November 17-19, Chicago, Ill.