This paper investigates the effect of curvature of structural members on nonlinear behavior of two-dimensional building frames. The RC moment resisting frames in two groups of medium (M) and high DUCTILITY (H) level, on alluvium (A) and bedrock (R) soil were considered for the analysis respectively.Totally, sixteen frames having 5, 8, 12 and 15 stories, with four bays of each 4m long, were considered.All frames were designed for H and M DUCTILITY levels according to Iranian standard 2800 for seismic design, and Iranian concrete code of practice (ABA) and then corresponded to the regulation of ACI- 2002.IDARC computer program is utilized for the nonlinear static analysis to investigate the capability of plastic hinge formation of different members during the various state of behavior (cracking, yielding and ultimate state). Linear relation between the overall curvature DUCTILITY and the overall displacement DUCTILITY of the multi-degree of freedom system is derived. From the derived relationship, the close relationship between the fundamental period and the relative energy dissipated (ratio of overall curvature DUCTILITY to the overall displacement DUCTILITY) is clearly obtained.

Experimental studies show that an indeterminate structure or a continuous concrete beam does not fail when critical sections reach their ultimate strengths. Therefore, if a structure has adequate DUCTILITY, stress and moment redistribution will take place in the flexural members by developing plastic hinges at critical sections. This causes the other points of beams to achieve their ultimate strengths and capacities. Besides, moment redistribution allows designers to adjust the bending moment diagram computed by elastic analysis.The usual result is a reduction in the values of negative moments at the support face as well as an increase in the values of positive moments along the span.In the current investigation, a parametric study on moment redistribution in continuous RC beams with equal spans under uniform loading was performed. First, the governing equation for the allowable percent of moment redistribution was extracted using DUCTILITY demand and DUCTILITY capacity concepts. The effects of different parameters such as the concrete compressive strength, the amount and the strength of reinforcing steel, the magnitude of elastic moment at the support and the ratio of the length to the effective depth of the continuous beam on moment redistribution were then investigated. Furthermore, the allowable moment redistributions were calculated according to the regulations of different codes in each case. The results showed that, whereas the permissible moment redistribution in continuous reinforced concrete beams based on the relevant rules in the current codes is not in a safe margin in some cases, it is rather conservative in most cases.

In seismic areas, DUCTILITY is an important factor in the design of high strength concrete (HSC) members under flexure. In order to investigate this, here in this study, eight HSC beams with different percentages of  r & r’ were cast and incrementally loaded under bending. During the test, the strain on the concrete middle faces, the tension and compression bars, and also the deflection at different points of the span length were measured up to failure. Based on the obtained results, the serviceability and ultimate behavior, and especially the DUCTILITY of the HCS members are more deeply reviewed. Also a comparison between theoretical and experimental results is reported here.

In this paper, results of experimental and analytical studies on a new type of infilled frames, having high DUCTILITY are presented. The studied infilled frames, regarded Engineered, had frictional sliding fuses at their midheights.The fuse could be regulated for a desired sliding strength in longitudinal direction, but was restrained transversally. In the first part of the paper, experimental results of two engineered infill specimens, with different sliding strengths of their fuses, are presented. Cyclic loads were applied to the specimens. It is shown that such infills have more stable hysteresis loops as well as higher ductilities, in comparison with regular infill panels.After having the experience of failure by in-plane loads, the specimens were tested again; one of them was repaired by grout and reloaded by the same loading protocol. The other one was loaded transversally to evaluate the out-of-plane strength of the engineered infills after being failed by in-plane loads. Results show that such infills have high transversal strengths and they can be efficiently repaired by grout. In the second part, behavior of the engineered infilled frames (EIFs) in real earthquakes are studied and compared with ones of bare frame and regular reinforced concrete infilled frame. For this, some nonlinear time-history analyses of a three bay frame with 1, 3, 5 and 7 stories were conducted by IDARC for five earthquake records. It is shown that the engineered infilled frames are efficient to improve seismic behavior of the considered buildings.

Self-consolidating concrete (SCC) is a relatively new approach to making concrete, and it is characterized by its high flowability and resistance to aggregate segregation in the plastic state. A total of 3 beams were tested in this experimental investigation on the flexural DUCTILITY of reinforced concrete beams made with self-consolidating concrete. The beams were made from concrete having average compressive strength of 30 MPa and reinforcement ratio in the range of 0.15-1.38. Three self-consolidating reinforced concrete beams with different percentage of and constant amount of were cast and incrementally loaded under bending. During the test, the strains on the concrete middle face and on the tension and compression bars as well as the deflection at different points of the span length were measured up to failure. This paper compares the DUCTILITY of reinforced beams cast with SCC concrete to the theoretical calculations based on two codes (ACI, CSA) recommended for the reinforced concrete members that vibrated into place to ensure proper filling and consolidation. Based on the results obtained, effect of increasing tension reinforcement on the curvature and displacement DUCTILITY of the self-consolidating concrete reinforced members is more deeply reviewed. Comparisons between theoretical and experimental results are also reported here. Generally, it was concluded that, self-consolidating reinforced concrete beams yielded greater DUCTILITY as opposed to the theoretical calculations based on two codes (ACI, CSA) recommended on conventional reinforced concrete beams.

In general, shear wall design is based on flexural DUCTILITY. In this design approach, behavior of the shear walls is more similar to a cantilever beam with significant bending moment at its base. In such systems, the main input energy dissipation during seismic events happens at the base of the shear wall. In this paper, in order to improve the behavior of these important lateral resisting mechanism in structural systems, the possibility of dual type behavior (flexural and shear) were investigated. At first, the potential of this approach in improving the behavior of shear walls has been examined in a simplified structural model. Later, three types of shear walls including slit walls, shear walls with opening and frame-wall systems have been studied. The results show the capability of dual DUCTILITY modes of behavior in all three systems. Energy dissipation dispersion in these systems is better than the ordinary shear walls. Among the dual DUCTILITY systems, the frame-wall system has shown a superior performance compared with that of the two other systems.

The idea of using steel plate shear wall as a lateral load resisting system in design and retrofit of structures has attracted the attention of researchers and designers for more than three decades. In this research, the DUCTILITY of thin steel plate shear walls are studied based on ATC-24 protocol and Popov’s definition. Two three-story unstiffened steel plate shear walls were tested under cyclic loading. In these tests shear walls had rigid and simple beamto-column connections. For the plate of panels, low strength steel and for the boundary frame high strength steel were used. In addition, some other valid tests on steel plate shear walls with different configurations, which were done in the world also, were considered. The results obtained from all of the tests show that the DUCTILITY factor in thin steel plate shear walls according to ATC-24 protocol and Popov's definitions can be assumed about 6.5 and 13, respectively.

The paper presents the results of a study on the performance of Glass Fibre Reinforced Polymer (GFRP) wrapped high strength concrete columns under uni-axial compression. The columns had slenderness ratios of 8, 16, 24 and 32. Chopped Strand Mat GFRP was used with 3 mm and 5 mm thicknesses. The columns were tested under monotonic axial compressive loading up to failure. The deflections were noted for each load increment. The HSC columns with GFRP wrapping exhibited improved performance in terms of strength and DUCTILITY capacity.

In this paper a simple tool for seismic design of steel structures for a selected DUCTILITY level is presented. For this purpose, a consistent set of earthquakes is selected and sorted based on the maximum acceleration of ground surface. The selected records are applied as the base motion to a single-degree-of-freedom system with strain hardening and the maximum response acceleration is determined for three levels of DUCTILITY. The response results of the nonlinear dynamic analysis are presented in the shape of the maximum acceleration of the system versus the peak ground acceleration for a certain DUCTILITY demand. Using these graphs, the maximum acceleration and base shear of the system are calculated by accounting for its nonlinear behavior, hence eliminating the need for the response modification factor. This is the main advantage of the presented diagrams for nonlinear seismic design of steel moment frames.