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In order to evaluate the seismic behavior of prefabricated panel structures by dry connectors (PPSDC) , two one-half scale two-story models were constructed and subjected to a series of quasi-static; tests. The joints of the two models were connected by bolted and welded connections, respectively. This paper presents the results from the tests, with focuses on the force transfer mechanism, the failure mode, the hysteretic behavior, the skeleton curves and their characteristic parameters, and the strains in the reinforcing steel bars. Based on the test results, the concept of ductile failure mode of the PPSDC is proposed together with the design principles for ductile joints in such structures. The test results show that the integrity and utmost bearing capacity of PPSDC are good, but the failure mode and characteristics of the PPSDC are obviously different from cast-in-situ structures and other prefabricated concrete structures. The punch-shear damage of concrete and anchor damage of built-in fitting are the main reasons for the failure of the two PPDSC models, respectively. In order to ensure the ductility and the deformation capacity of the PPSDC, the ductile design principles of 4 strong anchorage, strong peripheral and weak steel plate’ should be followed in the design stage, in which the connected steel plates are regarded as a main weakest component dissipating energy and the failure of different parts in the dry connectors could be controlled. [ABSTRACT FROM AUTHOR]

Experimental research was done to study the strength of welds for tubular X-joints with CHS braces to SHS chord. Five non-rigid and three rigid welded connections were tested under monotonie loading. The weld properties were specially measured by use of negative mold and the strain distribution around the weld, the failure modes and the strength of welds were studied. The test results indicate the uneven strain distribution in non-rigid connections, in contrast to the even strain distribution in rigid connections. The strength of welds for non-rigid connections shows a significant reduction compared with rigid connections. It could be explained by the uneven stress distribution of welds and the brittleness of the material in heat affected zone (HAZ). The material in HAZ fractures before the weld metal since it could hardly follow the plastic defamation of the wall of the chord for non-rigid connections. FE analysis was used to study the mechanical behavior of welds and effective length of welds was derived for joints with different parameters. The prediction formula for axial tensile strength of welds is proposed according to the method of effective length based on experimental research and FE analysis, which meets the reliability requirements in specifications. [ABSTRACT FROM AUTHOR]

In order to study the behavior of the weld of high strength structural steel Q460C under earthquake loading, 11 welded high strength structural steel Q460C specimens were tested by 8 different monotonic and cyclic loading regimes. The corresponding stress-strain relationships under these different loading regimes were analyzed. The constitutive model, mechanical properties, failure modes, deformation, ductility and the cumulative damage deterioration were also studied and compared with the behavior of the base metal. Based on the test results, the cyclic skeleton curves were fitted by the Ramberg-Osgood model. The key parameters in the formula were determined. Furthermore the key parameters of the stress-strain constitutive model of the weld of high strength structural steel Q460C under cyclic loading were calibrated by the test results and accurately simulated using ABAQUS with the mixed cyclic constitutive model. The results show that all specimens of welded connection fracture at the weld heat affected zone, which may be caused by the stress concentration. Welding process results in undesirable influence on ductility of steel structures. Measures should be taken to avoid failure at welded connections. [ABSTRACT FROM AUTHOR]