International Concrete Abstracts Portal

This CD-ROM contains 14 papers sponsored by ACI Committees 347, 350, 364, and 437. The papers represent a broad range of topics including; concrete mix design, design and construction, construction failures, formwork in concrete design, and more. Note: The individual papers are also available. Please click on the following link to view the papers available, or call 248.848.3800 to order. SP-285

In honor of Dov Kaminetzky, two case stories are discussed; one to reflect his passion for the correct usage and design for concrete and the other his other great passion, the forensic and technical evaluation of existing structures.

Analysis of the construction load distribution during construction of multistory concrete buildings is critical for both construction safety and economy. Recent reduction of load factors used in design of the permanent structure has resulted in less strength availability in the construction stage and need for tools to better support shoring and reshoring analysis. Using the traditional simplified method presented in ACI SP-4 for concrete structures under construction, spreadsheet models have been developed which analyze the distribution of loads based on inputs chosen by the engineer. The models determine the vertical loads resisted by temporary construction systems and the slabs with various combinations of levels of shores and reshores and with mechanical drophead shores. Analysis can be performed using either unfactored or factored loads and using either actual uniform loads or loads expressed as a proportion of slab dead load. The results of the models were validated by comparison with previously published shoring and reshoring analyses. Lastly, a comparison of the loads supported by the individual slabs and the levels of shores in each model during the placement of upper floors is made.

This paper describes the planning, design and construction challenges to replace the existing, 80-year-old 14Million Gallons (54.81 Mega liters) Chevy Chase Reservoir and Pumping Station, located in Glendale, California. The existing and new reservoirs were/are fully buried, reinforced concrete structures under a golf course in Chevy Chase Country Club. The new reservoir was built on the footprint of the existing reservoir, on a tight site, involving shoring and stockpile of earth to be utilized for backfill following the completion of the reservoir. The location is in a residential neighborhood along a busy street. There was heavy community involvement and the concrete truck traffic on pour days as well as the rebar deliveries had to be carefully managed during construction. This paper discusses the planning, pre-design, design, constructability review and the construction management including the various QA/QC aspects throughout the project. The inclusion of special provisions for demolition of the existing facilities and other special conditions are addressed. The existing reservoir did not last the anticipated life of 100 years for a buried structure, the lessons learned and how the new ACI 350 code was implemented into the new reservoir design will be discussed. Also, the leakage testing requirements are described. Unforeseen subsurface conditions and unexpected contaminated perched groundwater along with the mitigation methods to improve soil and foundation conditions are discussed. The project was completed in record time, through an incentive clause in the contract documents. The project utilized the existing concrete material by crushing and using it as the sub base of the new reservoir, eliminating the need for hundreds of truck loads of material to be hauled offsite, contributing further to the Owner’s “Green Initiative” and reducing the overall carbon foot print. Several unique features and the overall performance of the project will also be addressed.

Construction failures are not as rare as we wish them to be. They occur far more frequently than we realize or admit. A wide variety of construction failures occur every day ranging from life threatening dramatic collapses to many other Alow consequence@ failures and defects such as excessive floor sagging, concrete cracking, spalling, and honeycombing, increased long term deflections, bulges, misalignments, and failures that can cause serious maintenance and serviceability problems later in the life of the structures. Though there is no way that failures may be entirely eliminated, they can be minimized. How can these dangerous and costly failures be prevented? The answer is rather simple; it requires knowledge, competency, and care. Education and training are the only way to improve these qualities. The need for forensic education is essential. This paper provides a brief account on the cause and prevention of construction failures and non-performance. Failure case studies in concrete construction are presented. Failure investigations identify errors to be avoided and provide useful educational lessons to practicing engineers, as well as to engineering students. This paper argues the need for forensic engineering courses in engineering schools and provides suggestions on how these specific case studies can be integrated into a classroom instruction lecture. This paper is a dedication to Dov Kaminetzky who contributed largely in utilizing construction failures as an educational tool. His strong belief that the key to minimize failures is education is reflected in this paper which includes part of his work.