Selim Pul

Determination of rectangular stress block parameters for high performance concrete

Despite so much research on high performance concrete, the properties of this concrete are not known as well as those of ordinary concrete. There have been a lot of equations, rules and suggestions in the codes which are used in the design of reinforced concrete and prestressed concrete structures. They are obtained from experimental studies made on concrete that have compressive strength of less than about 40 MPa. It is not exactly known whether they could be used in the design of structures constructed by using high performance concrete. Therefore in this study, stress-strain and equivalent block parameters were obtained from experimental stress-strain diagrams for calculation of high performance reinforced concrete beams in flexure. The conclusions obtained from this study showed that determined rectangular stress block parameters can be used in the design of high performance reinforced concrete members in flexure.

Nondestructive monitoring of a pipe network using a MEMS-based wireless network

A MEMS-based wireless sensor network (WSN) is developed for nondestructive monitoring of pipeline systems. It incorporates MEMS accelerometers for measuring vibration on the surface of a pipe to determine the change in water pressure caused by rupture and the damage location. This system enables various sensor boards and camera modules to be daisychained underground and to transmit data with a shared radio board for data uplink. Challenges include reliable long-range communication, precise time synchronization, effective bandwidth usage, and power management. The low-cost MEMS technology, saved wiring cost, and simple installation without destructive modification enable large-scale deployment at an affordable cost.

The behaviour of high-strength reinforced concrete columns under low eccentric loading

In this study, the change of the behaviour of high-strength reinforced concrete (HSRC) columns under axial and eccentric load based on the ratios of transversal and longitudinal reinforcements was investigated. To do this, 2100 mm height and 200 mm × 300 mm cross-sectional sizes reinforced concrete columns which have different transversal and longitudinal reinforcement ratios were produced with high-strength concrete. On these produced columns, two different eccentricity (e = 25 mm and e = 50 mm) and axial (e = 0) loadings were done. The experimental and theoretical moment–curvature (M–K) relations were determined and compared with each other. Test results showed that in the HSRC columns, the ratio of longitudinal reinforcement did not changed the fracture type which was brittle, but when the ratio of transversal reinforcement increased, the type of fracture was changed. The M–K relation obtained from the experiments and the M–K relation calculated theoretically were in harmony. This showed that the material model which was used to determine theoretical M–K relation was suitable for HSRC.