No abstract

Bamboo is a construction material that has great potential to be utilized as structural material on building construction. Bamboo available in variety length and high strength-weight ratio that make it ideal to be used as main structural component of buildings, such as column, beam, floor, partitions or trusses structural elements. High strength bamboo material can not be fully utilized due to the constraints in the connection system. The connection system adopted in joining bamboo elements on bamboo construction significantly influences the strength as well as behavior of the structure. The existence of nodes at the end of bamboo culms may improve the strength of connection. In practice, however, it is nearly impossible to have all bamboo element with nodes at the end of bamboo culms. Therefore in design of strength bamboo connection should be based on condition of end bamboo culms without nodes. In this research, analytical method considering two strength criterions is verified with result from experimental work. Results of research show that shear strength is the smallest strength among others. As bolt is used as connector in bamboo connections, shear strength commonly serves as critical criterion that determines the connection strength. This paper presents the result of study aiming at determination of minimum distance of bolt to the end of bamboo culms without node. Tests conducted by giving tensile force on the bolt with certain distance based on the analysis of shear strength and bearing strength of bamboo. The results showed that the critical distance of bolt to end of bamboo culms without node is 4-5 times the diameter of bamboo. Two main criterion of connection failure, namely shear and bearing failures are considered.

High strength bamboo material cannot be fully utilized in construction projects due to the constraints of the connection system. The connection system element on the truss structure greatly affects the strength of the structure. Several studies have been completed to provide higher strength of the truss connections. However, the connection system is constrained by the costs of construction, availability of materials, equipment, skilled labored standardization. In this study, a connection system that possesses lightweight properties but with higher strength and lower cost while keeping the form of the bamboo being connected to remain natural has been developed. The proposed connection system consists of bolts, wooden gusset plates and special wooden clamps that have been adjusted with the shape and dimension of the bamboos being connected. A connection system without filler material on bamboo culms and wooden clamps used to increase the contribution to the shear at the connection has been proposed. The results showed an increase in the strength of the proposed connection of about 40% of the wood gusset plate system using wooden clamps than connection system without using wooden clamps, so it can be concluded that the proposed connection system possesses higher strength, yet much lower weight and has the potential for practical applications.

The study of wooden plate bamboo connection system with the addition of wooden clamp was carried out taking into account the variety the angle of the stems at the joint. The loading was preceded through the application of compressive force at the joint's member understudied up to reaching the maximum load and the connection was collapsed. It is known that the strength of bamboo not parallel to the direction of the fiber is lower than those parallel to fiber. Therefore, the strength of connection must be determined considering the strength of bamboo not parallel to the fiber direction. The experiment was carried out under static loading on the bamboo truss connections model with the various angle of connection stems of 0 o , 30 o and 45 o toward bamboo fiber direction. From the test result, it was found that there is a decrease in the connection strength at stem angle of 30 o and 45 o for about 16,80% and 12,21%, respectively, compared to the strength of the stem angle of 0 o . The test results also resulted the value of average elastic stiffness (Se) of the connection also indicates a decrease in the of elastic stiffness value (Se) of the connection for the stem's angle 30 o and 45 o for about 42,62% and 82,95%, respectively, compared to stem angle of 0 o . It can be concluded that there is a decrease in the strength and stiffness of the joints along with the increase in stem's angle of the bamboo truss connection system using wooden plate and clamp.

Cold-formed steel has been used widely on buildings, especially for the roof truss-structures. This material and its typical section are beneficial in weight and strength. Despite the minimum total weight, the structure can fulfil the strength requirement. For the truss installations, screws are commonly used to join the truss members due to time consideration and convenience process. However, there is a potential failure using the screw because it does not have a nut to prevent it from detaching. In this research, experimental tests of the screw connection of the cold-formed steel were conducted. The specimens consist of two groups: 8 specimens using screws were applied in the same direction and the other 8 specimens in the opposite direction. A different application of screws was aimed to observe the effect of the screw’s head, which may play a role as a nut to prevent detaching. Typical conditions of tilted screw and indented hole on the joined channel section were found during the test. The experimental results showed that the ultimate load for two different directions of screw were slightly different within the range of 0.4 – 10.0 %. The effect of the screw’s head position was minor to the resistance of the connection.