Vol.35/No.1(135)(2020)
| Title | Experimental study of reinforced concrete frame filled with high masonry window spandrel |
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| Author | Shuenn-Yih Chang, Bo-Han Su, Tsui-Huang Wu, Kuang-Ming Lou |
| Keywords | reinforced concrete building, highmasonry window spandrel, seismic evaluation, pushover analysis |
| Abstract | Taiwan areais characterized by high temperature and high humidity in summer. Hence, light and air are important in designing a building. To permit light and air to enter, windows are designed as large as possible. As a result, a window is located below the RC concrete beam, above the masonry window spandrel and between the two adjacent RC columns. This type of window is very unique in Taiwan area. Furthermore, to meet the requirement of concealment for storage room or restroom, high masonry window spandrels appear. Experimental studies of this type of masonry window spandrels are very rare. This might be due to the lack of large laboratories for conducting prototype tests. In the recent, a series of experimental studies on this type of window spandrels have been conducted by National Taipei University of Technology. In fact, the critical condition to experience a short-column failure has been identified and the cyclic-loading test results for the reinforced concrete frame filled with low masonry window spandrelshas been completed and published. In this work, two reinforced concrete frames filled with low masonry window spandrels were designed and fabricated. A cyclically loading test was performed for each test specimen. A formula for estimating the shear strength of a masonry window spandrel was proposed. |
| Title | The Effectiveness of Combined Ties on the Confinement of Encased Concrete-Filled Box Columns |
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| Author | Cheng-Cheng Chen, Pin-Da Wu, Yu-Lin Hsu |
| Keywords | Encased Concrete-Filled Box Columns, steel reinforced concrete column, concrete filled box column, SRC column, encased box column, combined tie |
| Abstract | In an encased concrete-filled box column, the concrete inside the steel box column is confined by the box column. However, the confinement of the concrete outside the box column (referred as outer concrete hereafter) need to be provided by the steel cage which is composed of main reinforcement and transverse reinforcement. Due to the existence of the steel box column, the traditional ties used in RC columns can not be implemented here. The use of so called combined tie was introduce to solve this problem. The confinement force was transferred from the first short tie bar to the box column and then to the second short tie bar located at the opposite side of the box column. In this article, six large scale (column size larger than 550×550) was tested under cyclic lateral loading to investigate the effectiveness of using the combined tie.The range of the width-to-thickness ratio of steel plate investigated was between 27 and 37, therefore the test result was applicable to column with width-to-thickness ratio less than 37. Some conclusion can be drawn based on the test results: (1) the combined tie can substitute the use of conventional tie bar, (2) the combined tie is effective in confining the outer concrete, and (3) the confinement effect contributed by combined tie can be determined using the cross section of the short tie bar. |
| Title | Axial Behavior and Test of Concrete-Filled Spiral Corrugated Steel Tubes Wrapped with Glass Fiber Reinforced Polymer |
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| Author | Chung-Sheng Lee, Chung-Che Chou, Hao-Hsiang Tan, V-Liam Chin |
| Keywords | Steel Corrugated Tube, Glass Fiber Reinforced Polymer (GFRP), Confined Concrete, Axial Compression |
| Abstract | This paper presents the axial behavior of concrete cylinders confined by a novel composite tube. This composite tube consists of a spiral corrugated steel tube and Glass Fiber Reinforced Polymer (GFRP) shell. The spiral corrugated steel tube serves as a mold for wrapping GFRP shell. The concave area of spiral corrugated tube are filled with pre-preg fiber strands and epoxy resins to form an enhanced flat tube, and a multilayer GFRP jacket are wrapped around the enhanced steel tube. Thirty-six cylinder specimens were designed and tested under uniaxial compression. The test parameters included different types of confinement tube and cross section. This paper proposes an analytical method to predict the axial behavior of concrete filled GFRP-wrapped spiral corrugated tube, and a calculation method for the ratio of effective confined area to predict the axial behavior of hollow section specimens. |
| Title | Buckling-Restrained Brace Out-of-Plane StabilityAssessment Using Notional Load and Failure Mechanism Analysis with Multi-Case Study |
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| Author | I-Chia Ou, Li-Wei Chen, Ching-Yu Tsai, An-Chien Wu, Keh-Chyuan Tsai |
| Keywords | buckling-restrained brace, flexural effect, out-of-plane stability, notional load, failure mechanism, second-order effects |
| Abstract | When the out-of-plane (OOP) instability of the BRB and the end gusset connections occurs, the energy dissipation capability of the BRB will be significantly reduced. This study develops a simplified analytical model using the concept of the notional load and considering the flexural restrainer to assess the BRB global stability. Cyclic loading tests on six full-scale BRBs with different lengths, steel casing sizes, and gusset connection stiffness were conducted under various initial imperfections and OOP drifts to demonstrate the effectiveness of the proposed method. Test results indicate that the effects of the initial imperfection, OOP drift, and gusset edge stiffener on the BRB stability are reasonably captured. Moreover, parametric analyses were conducted using the proposed method on 581 BRB and connection cases, detail designed by the Brace-on-Demand cloud service, with varying frame span-to-height ratios and brace yield strengths. Analytical results suggest that the stability limit strength is reduced by 12% to 15% with the OOP drift ratio increased from 1% to 2%,while it is reduced by 5% to 20% without the presence of gusset edge stiffeners.It is concluded that the global stability is vulnerable to the OOP drift and adequately stiffening the gusset is recommended in BRB practices. It also shows that as long as the demand-to-capacity ratio (DCR) is less than 0.9 for steel casing stability calculated by using the practical evaluation method, the overall stability can be effectively conserved. |