The Structural Design of Tall and Special Buildings

doi: 10.1002/tal.1180pmid: N/A

Gholizadeh, Saeed; Shahrezaei, Amir Masoud

doi: 10.1002/tal.1151pmid: N/A

SUMMARY Layout optimization of steel frames with steel plate walls (SPWs) using a meta‐heuristic search algorithm is the main aim of the present study. SPWs are lateral load‐resisting systems, especially against earthquake excitation. These systems offer significant advantages in terms of cost, performance and ease of design compared with other systems. In this study, orthotropic membrane model is used to model the behaviour of steel plate shear walls. The newly developed bat algorithm, which is based on the echolocation behaviour of bats, is employed as the present study optimizer. Design variables of the optimization problem consist of the cross sections of beams and columns of the frame, the web plate thicknesses of SPWs and the placement of SPW in the frame. The bat algorithm performs suitable selection of sections from the AISC wide‐flange (W) shapes list. Strength constraints of the American Institute of Steel Construction Load and Resistance Factor Design and displacement constraints are checked during the optimization process. The results reveal the effectiveness of the proposed method for optimization of steel frames with SPWs. Copyright © 2014 John Wiley & Sons, Ltd.

Tanarslan, H. M.; Kumanlioglu, A.; Sakar, G.

doi: 10.1002/tal.1152pmid: N/A

SUMMARY Using externally bonded carbon fiber‐reinforced polymer (FRP) for strengthening has been turned into a popular decision owing to its mechanical leads. Consequently, design guidelines and researchers have established several analytical equations to predict the contribution of FRP to ultimate shear capacity. The developed analytical equations projected the influence of FRP reinforcements within certain limits. However, not mentioned parameters such as the shear span‐to‐depth ratio and anchorage application influence the ultimate behavior of strengthened specimens. Accordingly, distant predictions between test results and code predictions are observed for the specimens in whom anchorage is applied. As an alternative method, artificial neural network (NN) can be used to predict the contribution of anchoraged carbon FRP to shear strength of deficient reinforced concrete beams. Accordingly, two NN models with back‐propagation are developed in this study. Unlike the existing design codes, the model considers the effect of anchorage and the shear span‐to‐depth ratio at the ultimate state. Artificial NN model is trained, validated and tested using the literature of 79 reinforced concrete beams. Then, NN results are compared with those ‘theoretical’ predictions calculated directly from International Federation for Structural Concrete, the American guideline (ACI 440.2R) and the Australian guideline. Within all theoretical predictions of design guidelines, fib14 provided the best predictions according to experimental results. Consequently, 25% of fib14 predictions are within ±10% of the experimental results, and also, 65% of the fib14 predictions are within ±25% of the measured values. Besides, executed comparisons indicated that the NN model is more exact than the guideline equations with respect to the experimental results and can be applied effectively within the range of parameters covered in this study. Copyright © 2014 John Wiley & Sons, Ltd.

Clemente, Paolo; Saitta, Fernando; Buffarini, Giacomo; Platania, Laura

doi: 10.1002/tal.1153pmid: N/A

SUMMARY The leaning Minaret of Jam, one of the tallest in the world, was declared as the Afghanistan's first World Heritage Site by UNESCO in 2002. The global stability analysis of the tower against soil collapse is first evaluated in the present configuration, in the hypothesis of increasing bending moment at the base section, assuming elastic‐perfect plastic behavior for the soil. Then, a finite element model is set up, which is used for the modal analysis and then for the seismic push‐over analysis, based on both single and multi‐modal approaches. Copyright © 2014 John Wiley & Sons, Ltd.

Li, Gang; Li, Hong‐Nan; Zhang, Yu

doi: 10.1002/tal.1154pmid: N/A

SUMMARY Significant effort has gone toward developing accurate and efficient displacement estimation procedures for the nonlinear multi‐degree‐of‐freedom (MDOF) system. Although the dynamic nonlinear analysis is capable of providing the high computational precision through the step‐by‐step time integration method, the simplified method is still expected and imperative for seismic design practices. The work presented in this paper focuses on the implementation of using the modal superposition method to estimate displacement responses of the nonlinear MDOF system based on the force analogy method (FAM). The current research demonstrated that the equation of motion for the nonlinear MDOF system can be decoupled, but other two governing equations in the FAM about the internal force, such as the moment and force of structural members, are not decomposable. Thus, the FAM is incorporated with the modal pushover analysis (MPA) method to determine the basic parameters of each mode such that the modal superposition method can be suitable for the solution of the nonlinear MDOF system. The procedure presented here is an approximately estimation method due to the application of MPA method. However, the value and potential for the maximum displacement estimation of the nonlinear MDOF system were demonstrated through the application in a framed structure. Copyright © 2014 John Wiley & Sons, Ltd.

Ren, Fengming; Zhou, Yun; Chen, Guangming; Liang, Jianwei

doi: 10.1002/tal.1155pmid: N/A

SUMMARY Three specimens of concrete‐filled steel tubular (CFST) frame‐shear wall structures with a scaling ratio of 1:4 were designed and tested in the present study. Two of them were installed with triple‐steel tube buckling‐resistant braces (BRBs). The seismic performances of the specimens were evaluated by testing them under lateral cyclic loading with constant axially compressive load being applied on the tops of the columns and the shear wall. The structural performances, such as failure characteristics, hysteretic behaviour, skeleton curve, strength degradation, stiffness degradation, energy dissipation capacity and strains at different locations of the three specimens, were measured and analysed in detail. The results showed that the load‐bearing capacity, the deformation capacity and the energy dissipation of the CFST frame‐shear wall structure were significantly improved due to the dissipation capacity of the BRBs, with the strength and stiffness degradation being obviously reduced. The results also showed that the CFST frame‐shear wall structure with BRBs has preferable mechanical behaviour and more reasonable failure mode. It was verified that the BRB can be used to improve the seismic performance of the CFST frame‐shear wall structure. Copyright © 2014 John Wiley & Sons, Ltd.