未加筋的低屈服点钢板剪力墙的结构性能英文文献和中文翻译(5)
As shown in Fig。 1, in-plane lateral load is applied to the beam– column connection in a displacement-controlled and incremental man- ner, and both geometrical and material nonlinearities are considered in the finite element analyses。
Numerical modeling of SPSWs is validated by considering the experimental results of two specimens tested by [13,5] representing SPSWs with respective slender conventional steel and stocky LYP steel infill plates。 The comparison details and results are illustrated in Figs。 3 and 4。 As it is observed in the figures, the agreement between the numerical and experimental results is quite satisfactory in both cases。
4。Advantages of use of LYP steel infill plates in SPSW systems
One of the significant advantages of LYP steel is its low yield stress of about 90–120 MPa, which is approximately 1/3 of that of ASTM A36 steel。 Use of such a low-yield steel in lieu of the conventional mild steels as the material for lateral force-resisting and energy dissipating ele- ments in buildings ensures early yielding of such structural elements, and consequently reduces forces imposed on frame members。 In fact, by employing LYP steel infill plates, it is easier to design the system in such a manner to let the infill plate yield prior to that of the surrounding frame and to ensure that the frame would not collapse before the infill plate reaches its ultimate strength [5]。 LYP steel shear walls, in addition, may be utilized to retrofit the existing frame buildings requiring addi- tional strength and stiffness。 Moreover, buckled and/or damaged infill plates of existing SPSW systems after an earthquake may be properly re- placed by LYP steel plates。 Such retrofits and/or replacements not only may increase the seismic performance, but also may enhance the struc- tural characteristics of the existing buildings in the light of use of LYP steel。
In this section, it is attempted to scrutinize the effects and advan- tages of use of LYP steel infill plates by addressing the abovementioned issues。 In order to achieve the objectives of this study, infill plate thick- ness in SPSW2 model is increased from 4。7 mm to 18。7 mm and the structural behavior and performance of the SPSW system and its com- ponents are investigated through finite element analyses。 It is noted that the boundary frame members in SPSW2 model were originally de- signed for 4。7 mm LYP and conventional steel slender web-plates as
ed by P。Y。 and F。Y。, respectively, and E。B。 stands for elastic buckling。
As shown in Table 1, the limiting plate thickness corresponding to simultaneous buckling and yielding of a 3000 × 3000 mm LYP steel infill plate is estimated to be 14。0 mm, so consideration of thicknesses below and above this limit will result in disparate buckling and yielding behaviors。 On this basis and as seen in Fig。 5, infill plates in SPSW2-4。7 and SPSW2-9。3 models yield in the post-buckling stage。 Infill plate in SPSW2-14。0 model, on the other hand, undergoes simultaneous buckling and yielding as expected, while that of SPSW2-18。7 model yields prior to buckling。
It is clearly observed that increasing of the infill plate thickness re- duces the interval between plate and frame first yield points。 However, yielding of the LYP steel infill plates in all cases occurs in advance of frame yielding due to low yield stress of this steel material, while yield- ing of the conventional steel infill plates in SPSW2-14。0 (Fig。 5(c)) and SPSW2-18。7 (Fig。 5(d)) models occurs unfavorably after frame yielding。 As seen in Fig。 5(c) and (d), early yielding of the frame members, espe- cially columns, results in significant stiffness and strength degradation and relatively weak performance of the system。 In addition, it is evident that LYP steel shear walls undergo early yielding and consequently large inelastic deformations compared to conventional steel shear walls with identical infill plate thicknesses。 This can be of great importance in seis- mic design of SPSW systems since the earthquake input energy can be