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SummaryA novel horizontal and vertical wall-to-wall and wall-to-floor connection methods for precast box-modularized structure with reinforced concrete shear walls (PBSRCSWs) are proposed in this paper. The entailing behavior of the proposed connections and the seismic performance of one full-scale six-story PBSRCSWs were experimentally studied by means of pseudodynamic substructure tests. In order to improve the relevant experimental accuracy, we presented and validated one versatile testing platform Hytest, combined with external displacement feedback control (EDFC; Hytest with EDFC). In greater detail, it was shown from the pseudodynamic substructure test results that the proposed Hytest with EDFC can effectively impose the desired displacements on the specimens rather than on the actuators. Moreover, both the horizontal and vertical wall-to-wall connections proposed for the PBSRCSWs exhibited a favorable behavior whilst the PBSRCSWs subjected to earthquake records showed an excellent seismic performance. KEYWORDSconcrete connection, external displacement feedback control, precast box-modularized structure, pseudodynamic substructure test, reinforced concrete shear wall, seismic performance

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Sn-58Bi is a eutectic alloy that melts at 139℃, it is leadfree and strong, but brittle. Also, its fatigue resistance is questionable [1]. The aim of this research is to study the properties of Sn-58Bi low melting temperature solder ball and the method to improve its reliability. 78 ball grid array (BGA) with ball size 0.45mm and 0.8 mm pitch was selected as the target device. Joint protect flux (JPF) was used to enhance the component side joint reliability. The result shows that JPF can solve the ball off problem and improve the ball shear, thermal cycling, drop life time and bending performance of Sn-Bi solder. Simulation work was succeeding to confirm the experiment results. The drop result is good if the Sn-Bi solder ball using Sn-Ag-Cu (SAC) paste, but the result is bad if the SAC solder ball using SnBi paste.