Seismic performance of steel structures with slit dampers

Free from damage beam-to-column joints: Testing and design of DST connections with friction pads

Post-tensioned self-centering moment connections with beam bottom flange energy dissipators

Experimental analysis of beam-to-column joints equipped with sprayed aluminium friction dampers

This paper presents the results of an experimental activity performed within the FREEDAM project, which is a project granted by the European Community devoted to the development of a new design strategy, for structures in seismic zone, based on the application of friction dampers in connections. In this work the attention is focused on the selection of materials to be employed as friction pads in FREEDAM joints, providing alternative solutions based on the application by means of thermal spray techniques of carbides and of metallic or intermetallic materials on steel plates. To date, twelve tests on eight different coating materials combined with stainless steel plates have been realized. The tests performed until now, which are mainly devoted to evaluate the behaviour of the friction interfaces in terms of static and kinetic friction coefficient and in terms of degradation, are inspired to the sliding test proposed by EN1090-2 adopting the loading protocol suggested by the EN12159 for the qualification of seismic devices. The initial value of the friction coefficient and its evolution during the tests, have been determined for the different materials by monitoring the values of the forces of the bolts used to apply the pre-load to the friction interface and the value of the sliding force. The obtained results are presented both in terms of force-displacement curves and in terms of friction coefficient, providing a comparison between the performances of the analysed interfaces in terms of energy dissipation supply.

Experimental behaviour of innovative thermal spray coating materials for FREEDAM joints

This paper presents an innovative structural system, named weld-free system, developed to overcome the difficulty in the quality assurance encountered in construction of steel moment resisting frames with conventional welded connections. The proposed structural system adopts a mechanical joint equipped with metallic-yielding damper as beam-to-column connection, wherein slip-critical joints are made by recently developed super high-strength bolts. The structural configuration and load-carrying mechanism of weld-free steel structures are described herein. Key features of the super high-strength bolts are also introduced. Furthermore, an experimental verification is presented. Cyclic tests were conducted on full-scale models of weld-free beam-column subassemblies and one base-line specimen with conventional welded connection. The test results clearly reveal the efficiency of the weld-free system in enhancing large and stable hysteresis loops while maintaining the beams and columns virtually in the elastic range until the ultimate state of the structure. It is also verified that the load-carrying mechanism of weld-free systems can be predicted very well by the presented theoretical solutions.

Seismic-Resistant Weld-Free Steel Frame Buildings with Mechanical Joints and Hysteretic Dampers

PROBLEM TO BE SOLVED: To provide a joining structure of a steel column and a steel beam capable of reducing work and execution work manhours of a column and beam member, of strengthening frame rigidity even if the cross-sectional size of a beam member is reduced and repairable only by replacing a joining element as a damage control frame at disaster time. SOLUTION: This joining structure of the steel column 1 and the steel beam 2 is formed such that a lower flange 2a or upper and lower flanges 2a and 2b of the steel beam 2 are fastened to the steel column 1 by bolts via an axial force resistance element 7, and are fastened to the steel column 1 by bolts via an axial force plus sharing force resistance element 4 on the steel beam end side from an installing part of the axial force resistance element 7 of the beam. The joining structure of the steel column and the steel beam is formed such that one flange of the steel beam 2 is fastened to a side part of the steel column 1 by bolts via the axial force resistance element 7, and the other flange is fastened to the steel column via an axial force plus shearing force plus bending force resistance element.

Joining structure of steel column and steel beam

PROBLEM TO BE SOLVED: To provide an earthquake-resistant construction, the working cost of which is reduced and which can display a vibration control function even against a big earthquake and a small one. SOLUTION: In the construction composed of columns made of steel and beams made of steel and braces, vertical-force transmission mechanisms 21 capable of transmitting vertical forces from brace materials 20 to the columns 1 and horizontal-force transmission mechanisms 22 capable of transmitting horizontal forces from the braces to the beams are installed to column side faces 1a and beam top faces or undersides at sites, where the brace materials 20 are joined with the columns 1 and the beams 2, and diaphragms for the columns 1 are dispensed with by mounting horizontal-force transmission mechanisms 24 capable of transmitting horizontal force from the beams 2 to floor structures 23 on the beams 2. COPYRIGHT: (C)2002,JPO

Earthquake-resistant construction

Mechanical behavior of bolted beam-to-column connections with buckling-restrained knee brace dampers

PROBLEM TO BE SOLVED: To provide a splice plate capable of forming a projecting part having a side section in the direction of plate width around a bolt hole contributing to a friction force, ensuring a slide coefficient of 10 or more, and achieving a compact bolt joining structure SOLUTION: In a splice plate used as caul when high strength bolts are friction-joined, a plurality of first projections 3 having concentric circle wave shapes are provided using a bolt hole 2 formed on a friction-join face of the plate as the center, and a plurality of second projections 4 are provided in the direction in which they cross the first projections to achieve a high slide coefficient for the longitudinal direction of the plate

Ichiro Takeuchi

Papers

Seismic-Resistant Weld-Free Steel Frame Buildings with Mechanical Joints and Hysteretic Dampers

Joining structure of steel column and steel beam

Earthquake-resistant construction

Mechanical behavior of bolted beam-to-column connections with buckling-restrained knee brace dampers

Splice plate for friction-joining high strength bolts