T型斷面加勁式鋼板阻尼器耐震設計與分析及試驗研究

Abstract

三段式鋼板阻尼器(3-Segment Steel Panel Damper, SPD)為一種金屬降伏型耐震間柱，由發生非彈性剪力變形之消能核心段(Inelastic Core, IC)與上下兩段彈性連接段(Elastic Joint, EJ)構成。上述SPD之IC段利用強度較低的鋼材或較薄的腹板來達成消能機制，常以焊接組合斷面製造。為降低SPD製造成本，本研究利用容量設計法，探討以熱軋斷面製造SPD之可行性，提出T型斷面加勁式鋼板阻尼器(WT Section-Stiffened SPD，簡稱WSPD)之製造與設計方法，及挫屈束制加勁板之建議設計流程。本研究亦提出WSPD彈性勁度之估算方法，並以此為基礎發展WSPD之等效斷面簡化模型與ETABS模型，以利工程實務應用。為驗證理論模型之正確性，本研究設計製造兩組WSPD試體: WSPD-8%-tw12-0L2T與WSPD-12%-tw12-1L2T，均採用SN400B鋼板製造連續長跨寬翼斷面，由H型斷面裁切之4個T型斷面來加勁EJ段，淨高均為2.6米，EJ深1024mm、標稱剪力強度866kN，兩組試體只有IC段加勁板設計參數不同，IC段挫屈發生前目標剪力變形量分別為8%與12%弧度。試驗結果顯示，以本研究所提方法製造之WSPD可提供預期之變形能力。試體0L2T與1L2T的強軸彈性勁度分別為155kN/mm及166kN/mm，與理論誤差在5%之內，而兩組試體發展之極限強度與理論誤差亦在5%之內，證明WSPD之強軸彈性勁度與極限強度可精準預測。試體0L2T在超過目標挫屈剪力變形量(8%弧度)之下一迴圈(峰值8.5%弧度)發生明顯挫屈，1L2T則在達目標挫屈剪力變形量(12%弧度)前一迴圈(11.4%弧度)即發生挫屈。試驗證明所提加勁板目標導向設計方法能大致控制挫屈時機。本研究並用Abaqus有限元素模型模擬試體之反應，成功預測WSPD的強度、勁度與遲滯行為。此外，本研究亦提出含WSPD及邊界梁十字形子構架的設計方法，並比較與貼版加勁式鋼板阻尼器十字構架及耐震間柱十字構架的勁度與加勁效率，顯示WSPD在增加勁度方面的優勢。

The 3-Segment Steel Panel Damper (TSPD) is a type of shear panel damper (SPD) which consists of an inelastic core (IC) and two outer elastic joints (EJs). The shear strength of the IC is weaker using a thinner web or weaker material than those of EJs, thereby dissipating seismic energy. Buckling restrained stiffeners are attached to IC web to delay shear buckling. Top and bottom end stiffeners stabilize IC and facilitate a robust force transfer between the IC and EJs. TSPDs are typically made of built-up sections. It might lead to a high fabrication cost. In order to develop a more cost-effective SPD fabrication procedure, this study investigates a new type of SPD, namely the WT-section stiffened SPD (WSPD). The WSPD can be built from a given hot rolled wide flange section and four WT-sections cut from it. This study also incorporates the capacity design method and develops a practical procedure for seismic design of WSPDs. The design procedure for the IC web stiffeners is re-constructed as well in this study. The WSPD elastic stiffness calculation method is different from that of TSPD as the WSPD’s geometry is rather unique. Considering the transition zones, the one element equivalent section model and the five element ETABS model of WSPD can be satisfactorily constructed using the proposed methods for practical applications. Two WSPD specimens made from using a 512×202×12×22 section, with a same height of 2.6m, the IC web thickness of 12mm, and a nominal yield strength 866kN were fabricated and tested. The two different target IC shear buckling deformations, 0.08 and 0.12 radians, resulted in two different stiffener designs for Specimen-0L2T and Specimen-1L2T, respectively. Test results show that the overall energy dissipation performance of the two specimens is excellent. Specimen-0L2T IC web buckled at 0.085 rad. right after the predicted buckling deformation of 0.08 rad., while Specimen-1L2T IC web buckled at 0.114 rad. earlier than the predicted buckling deformation of 0.12 rad. The elastic lateral stiffness and maximum shear strength computed from the proposed procedures are in good agreement with the experimental results, with errors less than 5%. Nonetheless, the experimental responses of the two specimens can be accurately simulated using Abaqus finite element model analysis. The stiffness of a moment resisting frame (MRF) can be enhanced by incorporating WSPDs, TSPDs and seismic stud columns (SSCs). This study incorporates the capacity design method for the seismic design of boundary beams. A total of twelve examples, each were designed with a largest damper shear strength considering the given boundary beams. By comparing the stiffnesses of the two half-height dampers connected to the boundary beam subassembly defined by the four inflection points, it’s found that the stiffness of WSPD subframe (WSPD-SF) is always the largest among the three different types of subframes. In addition, the stiffening efficiency of the WSPD is the best in most (75%) of the design cases.