No abstract

SUMMARYThe objective of this study is to investigate the e ect of boundary element details of structural walls on their deformation capacities. Structural walls considered in this study have di erent sectional shapes and=or transverse reinforcement content at the boundaries of the walls (called boundary element details hereafter). Four full-scale wall specimens (3000mm (hw) × 1500mm (lw) × 200mm (T)) were fabricated and tested. Three specimens are rectangular in section and the other specimen has a barbell-shaped crosssection (a wall with boundary columns). The rectangular wall specimens are reinforced according to the common practice used for reinforced concrete residence buildings in Korea and Chile. In this study, the primary variable for these rectangular specimens is the content of transverse reinforcement to conÿne the boundary elements of a wall. The barbell-shaped specimen was designed in compliance with ACI 318-95. The response of the barbell-shaped specimen is compared with those of other rectangular specimens. The e ective aspect ratio of the specimens is set to two in this study. Based on the experimental results, it is found that the deformation capacities of walls, which are represented by displacement ductility, drift ratio and energy dissipation capacities, are a ected by the boundary element details.

The shear-lag phenomenon is a critical consideration in high-rise building analysis and design. The shear-lag behaviour of framed-tube (including tube, tube-in-tube and tubes-in-tube constructions) is investigated for the behavioural characteristics of the structures and their performance in relation to the various structural parameters. The stiffness factor in terms of the axial stiffness of the columns and the bending stiffness of columns and beams is chosen as a main parameter to explain the shear-lag phenomenon and the global behaviour of the structures. A simple numerical technique is also proposed for estimating the shear-lag behaviour of framed-tube systems with and without multiple internal tubes. Further work is carried out to demonstrate the simplicity and accuracy of the proposed method through the analysis of three framed-tube structures (of different heights) without internal tubes and three other framed-tube structures with single, two and three internal tubes. The shear-lag phenomenon of such structures is studied taking into account the additional bending stresses in the tubes. Existing analysis methods for shear lagTubular structures have proved to be efficient for high-rise building construction. It is no wonder that a significant amount of research work has been done on the shear-lag phenomenon in framed tubes. However, existing methods have paid little attention to the net shear-lag phenomenon. In addition, comprehensive research into this area is minimal and the causes of the shear-lag behaviour and the tube-tube interaction have yet to be studied. Furthermore, previous studies have been devoted only to framed-tube structures without internal tubes.The occurrence of shear lag has long been recognized in hollow box girders as well as in tubular structures. Early studies were concerned mainly with steel beams having I and T sections. Box girders are often used in bridge construction. In the analysis of such bridges, Moffatt and Dowling (1975) and Kuzmanovic and Graham (1981) have studied the shear-lag phenomenon in steel box sections. Foutch and Chang (1982) and Chang and Zheng (1987) observed the negative shear-lag phenomenon in box girders. Since then negative shear-lag effects have been considered in box girder design. However, little effort has been made to understand the cause and the characteristics of such phenomenon.

No abstract

SUMMARYThis study focuses on the seismic performance of Ordinary Moment-Resisting Concrete Frames (OM-RCF) designed only for gravity loads. For this purpose, a 3-story OMRCF was designed in compliance with the minimum design requirements in the American Concrete Institute Building Code ACI 318 (1999). This model frame was a regular structure with exure-dominated response. A 1=3-scale 3-story model was constructed and tested under quasi-static reversed cyclic lateral loading. The overall behavior of the OMRCF was quite stable without abrupt strength degradation. The measured base shear strength was larger than the design base shear force for seismic zones 1, 2A and 2B calculated using UBC 1997. Moreover, this study used the capacity spectrum method to evaluate the seismic performance of the frame. The capacity curve was obtained from the experimental results for the specimen and the demand curve was established using the earthquake ground motions recorded at various stations with di erent soil conditions. Evaluation of the test results shows that the 3-story OMRCF can resist design seismic loads of zones 1, 2A, 2B, 3 and 4 with soil types S A and S B . For soil type S C , the specimen was satisfactory in seismic zones 1, 2A, 2B and 3. For soil type S D , the OMRCF was only satisfactory for seismic zones 1 and 2A.