PRECAST CONCRETE SHEAR WALL CONNECTIONS FOR SEISMIC ZONES
The precast concrete shear wall system is becoming very popular in North America for low, medium, and highrise construction due to the economical advantages possible with the ease and speed of assembly, and the high quality of the precast panels. The connections between panels are extremely important since they affect both the speed of erection and the overall integrity of the structure. This paper presents the results of the last two phases of a six-year research program conducted to investigate the behaviour and the capacity of fIfteen connection configurations used for precast load-bearing shear wall panels subjected to monotonic shear loading and large reversed cyclic loading conditions. Connection configurations include dry-packed plain surface, dry-packed plain surface with continuity reinforcement, dry-packed with two types of mechanical shear connectors in addition to the continuity bars, dry-packed with post-tensioning, and two types of dry-packed multiple shear keys. The research also include connections which support hollow-core slab with and without post-tensioning. The performance of new innovative connections, such as partial or complete debonding of the reinforcement continuity and the use of energy dissipating mechanical connections for the continuity reinforcement, were also examined. Three different levels of load normal to the connection to simulate the effects of gravity load were used. The research fmdings of this investigation were implemented in the design and construction of three 32-stories apartment buildings in Winnipeg, Manitoba. The connections considered in this study provided significant savings in construction time and cost. 1 Doctoral Candidate, Civil Engineering Departmeht, University of Manitoba 2 Associate Dean of Engineering and Professor, University of Manitoba PRECAST CONCRETE SHEAR WALL CONNECTIONS FOR SEISMIC ZONES K.A. Soudki and S.H. Rizkalla
BEHA VIOUR OF PRECAST CONCRETE SHEAR WALL CONNECTIONS UNDER LARGE REVERSED CYCLIC SHEAR LOADS
The performance of precast concrete load bearing shear wall panel structures subjected to earthquakes relies on the behaviour and integrity of the connections between the panels. Design of these structures requires the ability to predict the behaviour of the connections. This paper presents results of an experimental program conducted at the University of Manitoba to study the behaviour of horizontal connections for precast wall panels subjected to large reversed cyclic inelastic shear deformations. The study considered some of the typical connection configurations currently used in practice. Prototype specimens were tested under reversed cyclic shear loading with constant load normal to the connection to simulate gravity loads. The influence of mild steel reinforcement, post tensioning and shear keys on the behaviour of the connections was investigated. Test results were used to identify the contribution of each component of the connection and to determine the various limit states cyclic behaviour of the connection configurations. This paper presents a summary of the experimental program, discusses the experimental results and introduces design considerations for these types of connections.
Prediction of a representative point for rail temperature measurement by considering longitudinal deformation
Monitoring rail temperature is very important for determining the safe running speed of trains and to prevent buckling. In general, the maximum variation of the internal rail temperature can be >7 ℃ depending on the point of measurement. However, there is as yet no sufficient information about how to predict the measurement point to represent the thermal deformation due to temperature distribution. In this study, the authors report a new point, called the representative measurement point, at which the rail temperature can be measured. This point considers the average deformation of the rail through structural analysis by adopting experimental and actual rail temperature data. The authors designed and installed a measurement system similar to an actual rail environment. Using the system, various data were acquired (internal/surface rail temperature and weather data) for 10 months. On the basis of these data, an analysis was done to calculate the average deformation point through thermal analysis. Finally, the representative measurement point was proposed as the position at which the average deformation point converges regardless of weather or seasons. The authors believe that the method described herein is advantageous in that it could be used in a high-accuracy temperature-monitoring system and for predicting thermal deformation and buckling.