Internal algorithms for creep and shrinkage when substituted by approximate algebraic equations lead to the adoption of a computational procedure substantially independent of linear equations adopted in the time-dependent prediction model. Presented herein are the numerical results of stresses and strains of reinforced and post-tensioned concrete bridge box-sections where creep and shrinkage are considered. Field measurements of deformations have been recorded and compared with the corresponding numerical results obtained by utilizing a computer program. Results are presented in a graphical form. It may be concluded that the computer method is a convenient tool for describing the behavior of structural concrete sections considering creep and shrinkage in connection with performance and service ability.

Long-term behavior of in situ reinforced concrete columns in two structures during construction, occupancy, and service is reported. Extensive strain and moisture movements were made up to about 10 years of service, and long-term movements at 25 to 30 years were then estimated. The stress history experienced by the columns in the second structure was monitored through a stress meter embedded in one of the columns, and the influence of reinforcement and the time-dependent movements on the stress history is described. The gradual but significant stress redistribution with time and the resulting concrete-steel load transfer is also discussed. Results show that the time-dependent deformation in in situ columns occurred over a very long period of time and continue to occur at a very small rate. However, the majority of movements in the columns occurred during the first 5-year period after construction of the columns. It is shown that dead load appears to be the predominant load carried by the columns. The design steel stress has been exceeded in several columns within 10 years of service life; however, none of the steel is expected to yield in 50 years of service life. Based on the in situ performance of columns along with other available data, a design recommendation is made to incorporate the effects of load transfer from concrete to steel at the design stage.

In seismic zones, severe earthquakes occur within a certain period. However, the important functions of a concrete structure must be maintained after the earthquake. Hence, structures must be designed for safety during the earthquake and serviceability after the earthquake. The acceptable level of damage can be varied in accordance with the type and importance of the structure. When a reinforced concrete structure suffers significant plastic deformation, residual deformation and large crack opening in the structure are impaired. A new and rational seismic design method was proposed. The peculiarity of the concept of the design method is as follows: Seismic design should be performed to fulfill required serviceability after the design earthquake as well as required safety during the earthquake. High magnification factor due to dynamic response was introduced according to actual observation in the earthquakes. Reduction factor referred to the acceptable level of damages in the structure after the earthquake was introduced. The importance of design details was emphasized. Furthermore, the influence of axial compressive force on the ductility was pointed out.

Long-term durability of reinforced and prestressed concrete structures in U.S. nuclear power plants was identified as a critical issue in the feasibility studies of plant life extension. Evaluation of concrete structures at several operating plants included studies of known concrete degradation modes, performance of condition surveys/testing, and service life prediction. Results indicate that service lives of 60 or more years are achievable, provided that preservation activities are conducted for these concrete structures.

Concrete bridge decks have long been a problem for the design and construction industry. They have a tendency to crack and/or spall over time. The deicing process then creates problems because of salt intrusion into cracks. These cause spalling and ultimate deterioration of the reinforcing steel and the load-carrying ability of the concrete slab. The author wrote specifications concerning methods to produce a bridge deck that should be relatively crack free and thus enhance the long-term durability of the slab. Some items specified included long-term wet-mat curing, better concrete quality control, and a reduction of the water-cement ratio by 20 percent below standard specifications. He further discusses the utilization of retarders and high-range water reducers to accomplish the objective. The author then covers other methods in the literature such as epoxy-coated reinforcing bars as part of the overall process to produce a bridge deck that is relatively maintenance free over the long term.