SP-133 Design for serviceability and safety is central to the work of structural engineers, code-writing bodies and the users. The current era of high strength materials, exotic additives and limit states of design has necessitated better control of constructed facilities in their short and long-term behavior at service load and at ultimate load. This Special Publication concentrates on topics that give the design engineer and contractor an insight into how to avoid practices that could affect the integrity or long-term performance of structural elements and systems. The text is outgrowth of a national symposium of the American Concrete Institute co-sponsored by ACI Committees 348 and 435, and covers topics ranging from crack-control in reinforced and prestressed concrete, safety provisions in design codes and practical deflection computations to limit state design principles and seismic performance of frame structures. Several papers that could not be presented due to time limitations are included. The papers dealing with serviceability, highlight requirements of the ACI Codes and Reports in addition to relevant state of the art developments. The paper covering safety deal with issues ranging from philosophical discussions of treatment of safety in codes to project case studies. Overlap is expected since serviceability and safety are indivisible. All the papers presented in this publication were reviewed by recognized xperts in accordance with the ACI review procedures. It is hoped that designer, constructors and codifying bodies will be able to draw on the material presented in improving the safety and long-term cracking and deflection behavior of concrete constructed facilities.

The American Concrete Institute, Standard 318, Building Code Requirements for Reinforced Concrete have permitted the design of reinforced concrete structures in accordance with limit state principles using load and resistance factors since 1963. A probabilistic assessment of these factors and implied safety levels is made, along with consideration of alternate factor values and formats. A discussion of issues related to construction safety and safety of existing structures is included.

The paper presents a summary of treatment of serviceability design in the current Australian Code, AS 3600-1988. The backgrounds to the code rules with regard to control of deflection and crack widths are presented. The provisions for durability design of concrete structures are also discussed.

This paper presents the evaluation of seismic performance of a special moment-resisting (SMR) frame building and an intermediate moment-resisting (IMR) frame building designed in accordance with the NEHRP provisions and ACI Code 318-83. The annual limit-state probabilities for both SMR and IMR frames are determined by integrating the seismic hazard curve and structural fragility curve. From the comparison between the calculated annual limit-state probability and the specified acceptable risk levels, the seismic performance of a structure can be evaluated. In the NEHRP provision, if reinforced concrete frames are used to resist earthquake forces, the SMR frame is required for buildings belonging to higher seismic performance categories such as Categories D and E. Even though the SMR frame has a higher ductility than the IMR frame, the SMR frame is only designed for 50 percent of the strength required for the IMR frame. As demonstrated in this study, the IMR frame may perform better than the SMR frame in the event of an earthquake. Thus, the concept employed in the NEHRP provisions to protect high-risk and essential buildings needs careful reexamination.

Concrete bridges in the United States constitute about fifty percent of the total number of highway bridges. Recent studies indicate that many of these bridges deteriorate due to age, corrosion of reinforcement, fatigue, cracking and spalling of concrete, and/or human error. Limited funds are available for rehabilitation, strengthening, and replacement. Therefore, there is a need for methods to identify the parts of concrete girder bridges most sensitive to damage using reliability models. This may help lower the costs of checking, inspection, and repair. Load and resistance sensitivity functions for the ultimate flexural capacity limit state of simply supported bridge girders are included. The study indicates that the reliability of bridge girders depends mostly on the strength and location of steel.