Mousaad Aly

Wind-Induced Pressures on Solar Panels Mounted on Residential Homes

AbstractThis paper presents wind load investigations on solar panel modules mounted on low-rise buildings with gable roofs that have two distinct slopes. Wind loads on the solar panels mounted on several zones of the roofs were systematically investigated in a boundary-layer wind tunnel for different wind directions. The results from the wind-tunnel investigation are compared with ASCE provisions for residential bare roofs. The comparison shows a good agreement with the ASCE standard provisions for the main force resisting system. Nevertheless, the cladding loads on individual modules may be lower or higher than those on the corresponding area of a bare roof (depending on their location and array configuration and the roof’s slope). Avoiding the roof critical zones (zones 3 and 2) is recommended to avoid high net minimum pressures acting on the solar panel modules. Solar panels mounted in zone 1 are locally subjected to higher suction at their outer edges. This is most likely attributed to the effect of a...

On the evaluation of the efficacy of a smart damper: a new equivalent energy-based probabilistic approach

Smart damping technology has been proposed to protect civil structures from dynamic loads. Each application of smart damping control provides varying levels of performance relative to active and passive control strategies. Currently, researchers compare the relative efficacy of smart damping control to active and passive strategies by running numerous simulations. These simulations can require significant computation time and resources. Because of this, it is desirable to develop an approach to assess the applicability of smart damping technology which requires less computation time. This paper discusses and verifies a probabilistic approach to determine the efficacy of smart damping technology based on clipped optimal state feedback control theory.

Dynamics and Control of High-Rise Buildings under Multidirectional Wind Loads

This paper presents a procedure for the response prediction and reduction in high-rise buildings under multidirectional wind loads. The procedure is applied to a very slender tall building that is instructive. The structure is exposed to both cross-wind and along-wind loads obtained from pressure measurements on a rigid model (scaled 1 : 100) that was tested in a wind tunnel with two different configurations of the surroundings. In the theoretical formulation, dynamic equations of the structure are introduced by finite element and 3D lumped mass modeling. The lateral responses of the building in the two directions are controlled at the same time using tuned mass dampers (TMDs) and active tuned mass dampers (ATMDs) commanded by LQR and fuzzy logic controllers, while the effects of the uncontrolled torsional response of the structure are simultaneously considered. Besides their simplicity, fuzzy logic controllers showed similar trend as LQR controllers under multidirectional wind loads. Nevertheless, the procedure presented in this study can help decision makers, involved in the design process, to choose among innovative solutions like structural control, different damping techniques, modifying geometry, or even changing materials.

Vibration Control of Buildings Using Magnetorheological Damper: A New Control Algorithm

This paper presents vibration control of a building model under earthquake loads. A magnetorheological (MR) damper is placed in the building between the first floor and ground for seismic response reduction. A new control algorithm to command the MR damper is proposed. The approach is inspired by a quasi-bang-bang controller; however, the proposed technique gives weights to control commands in a fashion that is similar to a fuzzy logic controller. Several control algorithms including decentralized bang-bang controller, Lyapunov controller, modulated homogeneous friction controller, maximum energy dissipation controller, and clipped-optimal controller are used for comparison. The new controller achieved the best reduction in maximum interstory drifts and maximum absolute accelerations over all the control algorithms presented. This reveals that the proposed controller with the MR damper is promising and may provide the best protection to the building and its contents.

Active Control in a High-Rise Building under Multidirectional Wind Loads

Active control of a tall building subjected to wind loads is presented in this paper. A 48-story high-rise building (209 m height) equipped with two active mass dampers is used in this research. The structure is subjected to both across-wind and along-wind loads obtained for a rigid model (scaled 1:100) that was tested in the wind tunnel of Politecnico di Milano for two different configurations of the surrounding. The building alone is modeled dynamically using three-dimensional model with a total degrees-of-freedom of 144 (each floor has three degrees-offreedom: two lateral translations and one rotation about the vertical axis). The state reduced order technique is used for the control purposes. The lateral response of the building in the two directions is controlled simultaneously while the effect of the uncontrolled torsional response of the structure is considered instantaneously. Effects of the wind attackangle on the performance of the controlled system are studied. The results obtained show that both tuned mass dampers and active mass dampers have a great effect on the reduction of the displacement and acceleration responses of the building over a wide range of excitation inputs. However, it is found that controlling the responses in one lateral direction is more effective than that in the other direction due to the unequal effects of the vortex shedding and the torsional responses.

On the Design of High-Rise Buildings for Multihazard: Fundamental Differences between Wind and Earthquake Demand

In the past few decades, high-rise buildings have received a renewed interest in many city business locations, where land is scarce, as per their economics, sustainability, and other benefits. Taller and taller towers are being built everywhere in the world. However, the increased frequency of multihazard disasters makes it challenging to balance between a resilient and sustainable construction. Accordingly, it is essential to understand the behavior of such structures under multihazard loadings, in order to apply such knowledge to design. The results obtained from the dynamic analysis of two different high-rise buildings (54-story and 76-story buildings) investigated in the current study indicate that earthquake loads excite higher modes that produce lower interstory drift, compared to wind loads, but higher accelerations that occur for a shorter time. Wind-induced accelerations may have comfort and serviceability concerns, while excessive interstory drifts can cause security issues. The results also show that high-rise and slender buildings designed for wind may be safe under moderate earthquake loads, regarding the main force resisting system. Nevertheless, nonstructural components may present a significant percentage of loss exposure of buildings to earthquakes due to higher floor acceleration. Consequently, appropriate damping/control techniques for tall buildings are recommended for mitigation under multihazard.

Influence of Turbulence, Orientation, and Site Configuration on the Response of Buildings to Extreme Wind

Atmospheric turbulence results from the vertical movement of air, together with flow disturbances around surface obstacles which make low- and moderate-level winds extremely irregular. Recent advancements in wind engineering have led to the construction of new facilities for testing residential homes at relatively high Reynolds numbers. However, the generation of a fully developed turbulence in these facilities is challenging. The author proposed techniques for the testing of residential buildings and architectural features in flows that lack fully developed turbulence. While these methods are effective for small structures, the extension of the approach for large and flexible structures is not possible yet. The purpose of this study is to investigate the role of turbulence in the response of tall buildings to extreme winds. In addition, the paper presents a detailed analysis to investigate the influence of upstream terrain conditions, wind direction angle (orientation), and the interference effect from the surrounding on the response of high-rise buildings. The methodology presented can be followed to help decision makers to choose among innovative solutions like aerodynamic mitigation, structural member size adjustment, and/or damping enhancement, with an objective to improve the resiliency and the serviceability of buildings.

Design and Fabrication of a New Open Jet Electric-Fan Wall of Wind Facility for Coastal Research

This paper presents the design process of a new full-scale Wall of Wind (WoW) facility for wind engineering testing. Computational fluid dynamics (CFD) was used for a preliminary design of the facility, followed by an experimental verification of the wind field conducted with a small-scale replica. Results showed good agreement between mean wind speed profiles predicted by the CFD modeling and those measured experimentally, attesting to the growing importance of CFD simulations for wind engineering applications. The proposed full-scale 12-fan WoW facility will be able to engulf largeand full-scale models for future testing. The facility has been designed to generate wind and wind-driven rain with proper characteristics to mimic hurricanes up to Category 4 as defined by the Saffir-Simpson hurricane scale. The intent of the new facility is to improve wind-related building code provisions, to develop innovative hurricane mitigation techniques, and to help strengthen the resiliency of coastal communities to hurricane hazards.

Florida International University's Wall of Wind: A Tool for Improving Construction Materials and Methods for Hurricane-Prone Regions

Hurricane winds are one of the governing design environmental loads for structures. In coastal regions such as Florida, hurricanes cause enormous loss to life and property. Research focusing on the complex interaction between hurricanes and the built environment is therefore needed for developing a cohesive approach to build hurricane resilient coastal communities. At the International Hurricane Research Center (IHRC), Florida International University (FIU), research is going in stages on the construction of a large state-of-the-art Wall of Wind (WoW) facility for potential full- and large-scale wind engineering testing. In this paper, a technique for simulating hurricane winds at the WoW is presented and investigated. Wind profiles were simulated using turning vanes, and/or adjustable planks mechanism with and without grids. Assessments of flow characteristics were performed in order to enhance the WoWs flow simulation capabilities. The full-scale testing facility will be capable of generating hurricane wind and wind-driven rain field with proper characteristics to allow better understanding of category 1 to 4 hurricane (using Saffir-Simpson scale) effects on structures. The facility will be large enough to engulf full- and large-scale models of single-story buildings built using actual construction materials. This will help improve code provisions, innovative hurricane mitigation development, and producing solutions which bridge the disciplines of wind engineering and structural engineering.

Aerodynamic Loads on Solar Panels

The existing literature has limited aerodynamic data for the evaluation of design wind loads for solar panels. Furthermore, there are no provisions in building codes and standards to guide the design of these types of structures for wind. This paper presents a systematic wind tunnel study to evaluate wind loads on solar panels mounted on low-rise gable buildings. A preliminary geometric scale effect study using a simple isolated solar panel was carried out to permit design appropriate wind tunnel experiments. Following the scale effect study, wind loads on solar panels mounted on different critical zones of low-rise residential roof are systematically investigated. The results of the current paper provide useful information for the design of the solar panels.