الفهرس 
STATE-OF-THE-ART REVIEWOnly 14 pages are availabe for public view
 |  | from | 32 |  |  |
| | | from | 32 | | |
Abstract
ABSTRACT
Hollow structural sections are widely used in structural engineering applications and are often more preferred than the open sections (I-shapes) due to their aesthetic appearance and high strength-to-weight ratio. In many cases, the maximum capacity of such structure is governed by the capacity of its joints: failure of joints occurs before failure of members. Therefore, increasing the joint capacity in tubular structures would result in an economic design. Strengthening these joints capacities is a challenging issue for designers because of its closed nature.
This research program investigates a new strengthening technique for circular hollow sections (CHS) T-joints. The research focuses on T-joints subjected to brace axial compression forces, which are strengthened using different patterns of through-bolts to brace the outward deformation of the chord member and prevent chord ovalization.
The study includes an experimental investigation, which examines the efficiency of this strengthening technique. Finite element analysis is carried out to examine a wider range of parameters such as the class of chord member section (class 2, class 3 and class 4) and the pattern of through-bolts (one to four bolts spaced at 40 mm, 80 mm, 120 mm and 160 mm).
The effect of the washers shape on the strength and stiffness gain is also investigated by the finite element model. It was found that curved washers (against chord surface) enhance the efficiency of the adopted strengthening technique.
Based on the research outcome, strengthening of CHS T- joints subjected to brace axial compression forces using through-bolts is proven experimentally to be an effective strengthening technique. The strength gain is 35% using one bolt which presents a significant value compared to the cost and the weight added. The study revealed also that increasing the number of closely spaced bolts increases the joint capacity. An odd arrangement of the through-bolts is recommended for strength gain especially for large-spaced through-bolts so a bolt will be set at the middle of the joint. A bolt spacing value is proposed, limited to the studied parameters, to get the maximum gain in strength and stiffness.