The Structural Design of Tall and Special Buildings

Wu, Kai; Qian, Shiyuan; Zheng, Huiming; Zhou, Yukai; Zhu, Ruizhe

doi: 10.1002/tal.1984pmid: N/A

To address the problems faced with steel‐reinforced concrete (SRC) in construction, such as positional conflicts between steel and steel bars or difficulty in pouring concrete, a novel “Steel and Steel Fiber‐Reinforced Concrete” (SSFRC) composite structure was proposed. Push‐out tests of 34 SSFRC composite columns were carried out in this paper to study the interfacial bond performance from the perspective of energy dissipation. Based on loading‐displacement (P‐D) curves, the interfacial energy dissipation (Wb) and energy dissipation factor (λ) were introduced, and the influence of embedded length (Le), steel fiber volume rate (ρsf), thickness of concrete cover (Css), and section type on Wb and λ were analyzed. Test results indicated that circular column is better than square column in terms of Wb and λ. The increase of Le, Css, or ρsf is beneficial to the improvement of Wb, and λ is positively correlated with ρsf and Css but negatively correlated with Le. Additionally, the interfacial damage (Da) was defined by the relationship between elastic deformation energy (Wa) and Wb. It can be concluded that the ascent of Le and Css can effectively delay the appearance of Da and inhibit the development of Da, respectively, and Da develops slowly with the increase of ρsf at the later loading stage.

Chen, Zongping; Song, Chunmei; Zhou, Ji; Wang, Ni; Chen, Yuliang

doi: 10.1002/tal.1981pmid: N/A

Steel angle frame reinforced concrete (SARC) beam is a kind of composite beam with encased steel angle frame. The torsion tests were carried out on six SARC beams and one reinforced concrete (RC) beam to investigate their torsional behavior. Test variables include space between steel plates, angle of steel plates, concrete cover depth, and concrete strength. The results showed that the reduction of space between steel plates causes specimens to crack in advance, but improves torsional behavior after cracking markedly. The energy dissipation coefficient reduces as concrete cover depth increases. Damage index can be effectively reduced by increasing concrete strength, reducing plates spacing, and increasing concrete cover depth. The overall torsional behavior of SARC beam can be improved by reducing the spacing between the plates, adopting staggered vertical and oblique steel plates, and increasing concrete strength, but the effect is adverse when concrete cover depth increases. Moreover, the space between steel plates should be greater than 100 mm, and concrete cover depth should be less than 35 mm for maximizing the torsional strength of steel angle frame. Considering the positive roles of steel angle frame and oblique steel plates, the calculation methods of cracking and ultimate torsional moment were proposed. This study can provide a theoretical basis for the engineering application of SARC beams subjected to torsion.

Nieto, Félix; Cid Montoya, Miguel; Hernández, Santiago

doi: 10.1002/tal.1982pmid: N/A

Shape optimization is an effective tool to improve the aerodynamic performance of tall buildings by introducing minor modifications to the original project. Nevertheless, economic criteria demand efficient cross sections aiming at maximizing the building's profitability. These two contradictory criteria are commonly handled by adopting multi‐objective optimization approaches seeking the definition of Pareto fronts. However, the aerodynamic nonlinear features of low‐aspect‐ratio cross sections typically adopted in architectural practice can cause wind‐induced acceleration response surfaces over the considered design domain with multiple local minima that eventually lead to discontinuous Pareto fronts with non‐convex regions. This study delves into this problem and proposes a design framework that effectively combines the reduced basis method with multi‐objective optimization techniques to carry out the aerodynamic shape optimization using surrogates trained with CFD simulations. The ability of the optimization strategy to properly define the non‐convex regions of discontinuous Pareto fronts is successfully leveraged by adopting the weighted min–max method.

Liang, Kun; Su, Ray Kai Leung

doi: 10.1002/tal.1985pmid: N/A

Fragility analysis is an effective tool used to assess the seismic risk of high‐rise buildings. During the process of fragility analysis, determining the engineering demand parameters (EDPs) corresponding to different damage states is of great importance as they directly influence the fragility results. However, for buildings with transfer structures, the EDPs corresponding to different damage levels are difficult to determine since the maximum demand in such buildings is mostly concentrated at the level of irregularity. Obtaining the fragility curves at component level (as used for bridge structures) may provide new insight into the seismic fragility analysis of buildings with transfer structures. Due to differences in structural systems and seismic response, it may be questionable whether such an approach can be directly applied to the fragility analysis of high‐rise buildings. In view of this, a component damage‐based approach suitable for high‐rise buildings and a detailed framework through which to obtain the fragility curves are proposed in this study. This method was applied to assess the seismic risk of a 34‐story concrete building with a transfer plate. The damage states for various structural components were obtained through a damage index (DI) model. The relationship between the DIs of the components and the maximum inter‐story drift ratios (MIDRs) was generated by cloud analysis, and MIDRs corresponding to different component damage states were obtained. The fragility curves at both component and system levels were evaluated. Numerical results indicate that, at the conservative level of PGA (0.2 g), the probability that the main components of the building incur irreparable damage is small, and the performance‐based seismic design requirements can be met.

doi: 10.1002/tal.1881pmid: N/A

No abstract is available for this article.