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Although structures with elastic response are fairly well understood, structures with inelastic response are more difficult to analyze. Furthermore, in studies of inelastic response, attention has generally been paid to the response of reinforced concrete structures with relatively little attention being given to pounding of reinforced concrete buildings. Generally, the mutual collisions, or pounding, result from excessive deflections of adjacent buildings. In this paper, an algorithm is described for computing the pounding response of reinforced concrete buildings. In this situation, the buildings are idealized as two-dimensional multi-degree-of-freedom systems with nonlinear force-deformation characteristics. Collision between adjacent masses can occur at any level and are simulated by means of impact elements. Using real earthquake motions, the effect of deflection is investigated. In this study, the following conclusions are found. 1. Pounding can cause high overstresses, mainly when the colliding buildings have excessive deflections. 2. The code-specified separation distance is adequate to prevent pounding. 3. Pounding problems of adjacent buildings with large difference in mass are common.

An optical technique has been developed whereby two angles and linear displacement can be simultaneously measured in a noncontact manner. The method depends upon the usage of a diffraction grating with linear variation of period along its length. The grating is attached to a structure at a point of interest, while all other system components are placed at a remote location. Evaluation of this measurement technique has been demonstrated on a laboratory- based structure, which simulated conditions found at deep trench (or tunnel) walls or bracing systems. In a construction site configuration, this sensor allows the user to determine if the walls are undergoing structural deformation. In addition, the magnitude of deformation may be measured and alarm conditions may be monitored. Experimental results obtained using this technique are presented and compared with theory.

Use of prestressed prisms as main reinforcement has been demonstrated to be effective in limiting cracks and reducing deflections in high-strength, high performance concrete beams. To further understand the load-deformation history of such type of structural members, computer-simulated analysis has been conducted. A nonlinear analytical model based on strain compatibility was established. Theoretical predictions are compared with the experimental data obtained by the authors. Comprehensive computer-simulated flexural tests were also performed on a theoretical member section to further identify the variables which may affect the structural behavior. Parametric study suggests that the section ductility is mainly controlled by the reinforcing index. The influences of the effective prestress and concrete strength on ductility is found to be insignificant. Fiber optic Bragg-grating sensor technology was developed and used to internally and externally measure the deformations and cracking in the specimens.

North American design codes offer two methods to insure deflection serviceability. The design engineer can calculate the live load and sustained load deflections and check that they are less than code specified limits. Alternatively, the codes give maximum span/depth ratios for which serviceability can be assumed to be satisfied and deflections do not need to be calculated. However, the span/depth provisions of ACI 318-89 and CSA A23.3- M84 do not consider many of the factors which influence the deflection behavior of reinforced concrete beams and may not be consistent with the code specified deflection limits. The immediate and long term deflections of reinforced concrete beams were calculated using a layered, nonlinear finite element model. The long term deflections were calculated by a hybrid technique using an effective reduced modulus for concrete creep and a conventional finite element, time-dependent load vector for shrinkage and tensile cracking. The modelling technique was verified using the extensive experimental data of Christiansen. Span/depth ratios are proposed, which include the effects of concrete strength, tension steel ratio, and compression steel ratio, for incremental deflection criteria of span/500 and span/250. Long term deflection multipliers are given for sustained moments of 30, 50, and 70 percent of the design ultimate moment.

An 8000 sq ft (740 sq m) portion of an industrial building was load tested and vertical movements measured to an accuracy of 0.0043 in. (0.11 mm). Measured deflections were compared to those estimated before testing and to revised estimates after testing. Using simplified procedures and judicious estimates of design parameters, computed deflection normally should be within 40 percent of actual average deflection; the coefficient of variation should be less than 50 percent. With a complete and accurate selection of design parameters, the accuracy and statistical variability can be improved to 15 and 40 percent, respectively.