Jin-Hee Ahn

Experimental Evaluation of the Shear Resistance of Corrugated Perfobond Rib Shear Connections

Push-out tests were carried out to examine the shear strength of corrugated perfobond rib shear connections. The corrugated perfobond rib shear connection, formed by folding the straight perfobond rib steel panel, can be expected to increase the shear capacity and ductility of a shear connector due to the shear resistance and deformation of the inclined rib panel. To examine the shear behaviour of the corrugated perfobond rib connection and compare it with that of the perfobond rib, the push-out specimens were fabricated to suit the shear corrugated rib resistance parameters of depth of rib, height of rib, holes in the corrugated rib and whether transverse rebar is placed in the corrugated rib holes. Results of the push-outs show that the failure of corrugated perfobond rib shear connection is determined by concrete bearing and small deformations of inclined perfobond rib panel. Specifically, the corrugated rib specimens showed different relative slips at each side of the composite interface owing to the stress flow along the inclined rib developed by inclined direction of the welded corrugated perfobond rib. The transverse rebar in the rib hole reduced the difference in relative slips. The shear strength of the corrugated connection is increased by about 198∼512% compared with the standard perfobond rib specimen connection with transverse rebars and without transverse rebars respectively. However, the contribution of other shear resistance parameters is found to be relatively small compared with the contribution provided by transverse rebars in the rib holes. In terms of the ductility of the shear connector, the relative slip of the corrugated rib connections increased after ultimate load, so it is evaluated to have a sufficient ductility.

Life-cycle cost analysis of a TPSM applied continuous composite girder bridge

Transverse cracks in composite girder bridges are repeatedly reported because the tensile stresses in the concrete deck induced by the negative bending moment at the intermediate supports of continuous composite girder bridges. The occurred transverse cracks rapidly deteriorate the concrete deck, giving rise to frequent need for maintenance work. Prestressing methods are usually utilized in this kind of situation for the concrete structures, however no effective and feasible method has yet been proposed for steel-concrete composite structures. A new type of prestressing method entitled Thermal prestressing method (TPSM) has been proposed for innovative construction of continuous composite girder bridges, as effective prestressing method to prevent the occurrence of the tensile transverse crack of the concrete deck at the negative bending moment regions. In this study, the methodology for the economic analysis of TPSM applied bridges and case studies are introduced based on the life-cycle cost, considering initial construction cost and maintenance cost, to demonstrate the financial viability of the TPSM applied bridges compared to conventional continuous composite girder bridges.

Behavior of Partially Earth Anchored Cable-Stayed Bridge Considering Construction Phase and Operational Phase

In this study, the behavior of a cable-stayed bridge with a partially earth anchored cable system was studied both for the construction phase and for the operational phase. The recently constructed 3- span cable-stayed bridge with a usual self anchored cable system in Korea was modified into a partially earth anchored cable system. According to the FCM construction method, the construction sequence analysis was performed to find optimal cable stressing forces. Effects of the systems with partially earth anchored cables were examined by comparing the self anchored cable system. The behavior of the partially earth anchored cable-stayed bridge in the operational phase was investigated. The live load analysis was carried out according to the Korean vehicle class. Also, the response spectrum analysis for the seismic load and the buffeting analysis for the wind dynamic load were carried out. From these results, it is shown that the partially earth anchored cable-stayed bridge increases the resistant capacity against the service loads.

Multi-support excitation shaking table test of a base-isolated steel cable-stayed bridge

A series of tests was conducted for full-scale single-pylon asymmetric cable-stayed bridges using a system of multiple shaking tables. The 2-span bridge length was 28 m, and the pylon height was 10.2 m. 4 different base conditions were considered: the fixed condition, RB (rubber bearings), LRB (lead rubber bearings), and HDRB (high damping rubber bearings). Based on investigation of the seismic response, the accelerations and displacements in the axial direction of the isolated bridge were increased compared to non-isolated case. However, the strain of the pylon was decreased, because the major mode of the structure was changed to translation for the axial direction due to the dynamic mass. The response of the cable bridge could differ from the desired response according to the locations and characteristics of the seismic isolator. Therefore, caution is required in the design and prediction in regard to the location and behavior of the seismic isolator.

Shear Strength Evaluation of the Wave Perfobond Rib Shear Connector

Recently, steel and concrete composite structures are widely used due to the efficiency. In composite structures shear connection should guarantee the composite behavior of two materal. This should be ensured by the capacity of shear connector in the composite structures. In this study, a modified perfobond rib shear connector (wave perfobond rib), is proposed. Push-out tests have been performed to evaluate the shear strength of the proposed wave perfobond rib shear connectors based on Eurocode-4. Various shapes of wave perfobond have been examined to evaluate the effectiveness of some important parameters according to the sensitivity of structural behavior. The parameters considered in this study includes the existence of the holes, the diameter of the holes, the existence of transverse rebar, the diameter of transverse rebar, and the diameter of wave rib curvature.

Static Behavior of Composite Beam According to the Degree of Shear Connection Considering the Stud Shear Connection

In the construction of composite beam, two kinds of materials which have different properties require connector helping each other to behave similarly. For this purpose its necessary to use the shear connector which takes a role of bonding both materials. Composite materials can classify the connection of both materials as full interaction, and partial interaction. And it is full interaction that able to demonstrate the best efficiency of composite section. In this study, to evaluate the bending capacity of stud, which is popularly used in composite beam, the studs of different dimensions is installed in the each specimens and push-out test was taken for investigating the variation of shear strengths when the degree of shear connection changes. Also to evaluate ultimate loads when the degree of shear connection changes, three composite beams which have same section and different stud dimensions were manufactured. Compared the results of each experiment with those of the Finite Element Analysis, the effect of degree of shear connection to the composite beam and relationship between ultimate loads and the variation of degree of shear connection are estimated.