Effect of the Shape of Bracing for R/c Tall Building Frames on the Internal Forces in the Frame Elements

Due to the sensitivity of concrete frames to the lateral displacement especially in the case of tall buildings, it is useful to improve the behavior to resistance the lateral displacement through bracing. Bracing can be used in cases of rehabilitation and increasing the efficiency of existing concrete buildings. Varied shapes of bracing for concrete frames in order to achieve opening for windows and doors in the wall of frames. The research aims to give an idea for designer on the effect of the shape of bracing on the cross section forces generated in the elements of R/C tall buildings frame elements. The Study was conducted on R/C frame which consist from five spans, and fifteen storeys. It has compared different shapes of metal bracing, which are X, V, K and O. Calculation were based on Program CSI-SAP 2000. Conducted compared for the storylateral displacement of concrete frame in relation with the bracing shape. It shows that the bracing have large effect to reduce the storey lateral displacement, in the case of the bracing with X and V shape decreased the value of displacement in the last story in ratio 52.38%, in the case of bracing with K and O shape decreased in ratio 23.07%. Conducted detailed comparison for the value of cross section i.e. Moments, shear and axial forces in beams and columns of first and second floor frame in relationship of bracing shape. It concludes thatX and V bracing have large effect on the concrete tall buildings frame, as well as in the cases of improving the efficiency of existing R/C frame buildings.

Experimental Investigation of The Wall Pressure Distribution in a Barrel Silo with an Upper-cone with Downer- truncated cone Insert

The aim of this paper is to present a recent experimental investigation of the wall pressure distribution observed during the emptying of a modeling silo, with and without inserts for four different heights hi of the insert base above the hopper outlet. The experiments were carried out with corn, at the concrete lab. in faculty of civil engineering in Damascus university in Syria. The results show that the upper-cone with downer- truncated cone insert had a strong influence on the pressures in the silo.

Studying the Influence of the Distribution of Carbon Rods in the Sections of Reinforced Concrete Beams with Hybrid Reinforcement on their Flexural Behavior

The mixed use of steel bars and carbon rods in concrete beams can offer beams with different behaviour from that of steel reinforcement only. This paper studies the case of reinforcing concrete beams with two layers of bars, and the main para­meters investigated are the proportion and the distribution of carbon rods in the cross-section. Four groups containing 12 beams are tested, and each is reinforced with 4 bars located in two layers. The first group includes three control beams reinforced with steel bars, while the second includes three beams reinforced with carbon bars. Each of the third and fourth groups includes three beams reinforced with two steel bars and two carbon bars, whereas in the third group, steel bars are located above carbon ones, but in the fourth group, steel bars are located under carbon ones. Concrete beams reinforced with carbon rods in the second group exhibit a higher load carrying capacity and deflections, compared with other beams. However, the beams in the third and fourth groups have approximately the same load carrying capacity and the same behaviour up to the load level equal to 75% of their load carrying capacity. But after that, the beams in the fourth group become more deformed, compared with those of the third group.

The crack extended resistance in concrete and the effect of material properties on it

The extended crack resistance of concrete is necessary in the desisn of nonlinear behavior of structural It can be described through the intensity stress factor and the critical crack opening under maximum force. The length of the crack is necessary for calculating intensity stress factor and the critical crack opening under maximum force. The aim of this work is to conehede the relations between intensity stress factor and the critical crack opening under maximum force with the material properties of concrete such as paste volume, compressive strength and maximum aggregate diameter. The length of crack is calculated using the analytical model of Olesen that depends on bilinear softening, and the parameters of the softening curve were found using inverse analysis. The experimental results of three point bending test for beams with different sizes which are made from concretes with different compressive strengths are used in the inverse analysis. It is found that intensity stress factor and the critical crack opening under maximum force depend on paste volume and they increase when F'c increases, while they are independent from maximum aggregate size.

Studying the effect of the opening discharge diameter in cylindrical silo on the flow pattern and wall pressure

This paper presents an experimental investigation of the flow pattern and wall pressure due to the change of the opening discharge diameter in cylindrical silos. The experiments were performed on a metal silo prototype using corn as a granular material. The silo prototype used in the study was built of a metallic cylinder, which can be opened longitudinally allowing the observation of the flow pattern through a plexi-glass wall, and the wall pressure distribution was measured using a special granular pressure transducer. The present study revealed unexpected results to what might be expected through current theoretical knowledge.

The Effect of Fiber Reinforced Polymer Strengthened RC Beams on cracks width

This paper makes an experimental and analytical investigation of cracks characteristics in Fiber Reinforced Polymer strengthened RC beams under different levels of sustained load and Reinforced ratio. As the equations available for conventional RC beams are inappropriate for the calculation of the short-term crack width in FRP-strengthened RC beams[8], a statistical analysis is carried out on available test data from international sources [6-9-10] and from the test results obtained in the current study (Concrete Labor- Civil engineering Department- Damascus University-2014) to establish a new equation that considers the effect of the FRP laminates. This equation is a correlation of stress in steel bars, concrete surface tension , and effective side cover. The long-term crack width is then related to the instantaneous crack width by empirical equations which are derived from the test results obtained in the current study.

Upgrading The Seismic Reinforced-Concrete Frames Using Steel Plate as Partial Shear Walls

Frame structures contribute to resist the seismic loads. On the other hand, frames work efficiently to increase the ductility of buildings. Therefore, many techniques were used to improve the resistance against lateral loads where steel shear walls are considered to be one of these ways. This research aims to study the effect of inserting steel shear wall on the resistance of the reinforced concrete frame against earthquake loads. In this study, Finite Element Method (FEM) using Geometrically and Materially Non-Linear Analysis (GMNLA) was performed. Pushover analysis is used to explore the behavior of the steel plate in-filled reinforced concrete frame against lateral loads. Moreover, the effect of plate thickness was undertaken. On the other hand, an opening is made in this plate. Then, the influence of the position and dimension of this opening on the resistance was observed. This study shows that using a steel plate shear wall with or without opening can enhance the resistance to seismic loads significantly together with the deflection decrease.

Estimation of Monthly Reference Evapotranspiration in Safita Area by using Artificial Neural Network

Evapotranspiration forms one of the hydrology cycle elements that it's hard to measure its actual amounts in the field conditions, so it’s estimated by calculations of experimental relations that depend on climatic elements data. These estimations include different errors because of approximation processes. The research goals to accurate estimation of the monthly reference evapotranspiration amount in Safita area (on the east coast of the Mediterranean Sea), and the research depends on the technique of Artificial Neural Network (ANN), and the mathematical model was built by the (nftool), which is one of the Matlab tools, depending on monthly air temperature and relative humidity data which were taken from Safita meteorological station, and the data of monthly pan evaporation (Class A pan) has been used, after modifying its results, for the purpose of checking the performance accuracy of the network, by using Simulink technique, which is existing in Matlab Programs Package. The results of the research verify that a multi-layer ANN of error Back-propagation algorithm gives a good result in estimating monthly reference Evapo-transpiration for the used data group.

Geometrical Nonlinear Analysis Based on 2th order theory of two and three dimensional Framed Structure Using a Modified Finite Element Method

In this work, a modified finite element displacement approach is used to analyze two and three dimensional Framed Structure. The element is based on second order theory.

Spectral Matching by Wavelets vs. ASCE Ground Motion Uniform Scaling in Time Domain

Design ground motions are typically prescribed by smooth response spectra. Engineers often prefer to use a time history that matches the target design spectrum rather than evaluate a structure for a sit of time histories that are representative of the target spectrum in an ensemble average. Generally, scaling actual time histories to match a given design spectrum can be made by two preferred methods: First, ground motions uniform scaling in time domain which is simply scaled up or down the ground motion uniformly to best match the target spectrum within a period range of interest, without changing the frequency content. Second, spectral matching in time domain which produces only localized perturbations on both the time history and the its response spectrum, where small adjustments can be made to a time history to change its response spectrum from jagged to smooth, if done properly the resulting time history can be “realistic”. The realistic nature of a time history should be judged in the time domain in terms of the non stationary character of acceleration, velocity and displacement, for that the effectiveness of the two methods is examined by applying them to adjust actual earthquake time histories to much the design spectra while minimizing perturbations on their characteristics. The procedures are utilized to scale 15 set of records, every set consists of seven records of available real records to match the Syrian design spectra. The resulting time histories are investigated and compared in terms of suitability as input to time history analysis of civil engineering structures