م.احمد كامل كاظم الكلابي

Three scaled concrete slabs were cast and tested till failure under drop-weight impacts and static loads, sequentially. Two of the three slabs contained 0.5% steel fiber while the third slab was constructed by using only steel bar reinforcement (i.e., ordinary reinforced concrete). The obtained data from the testing program were used to distinguish between the performance of traditional reinforced concrete and steel fiber concrete slabs under impacting and static weights and to establish a data base for the upcoming studies pertaining to this research area. The test results and observations showed that the extension of steel fiber to the ingredients of concrete was efficient in decreasing crack widths and softening local damage under dynamic and static loads. On the other hand, reinforcement was more effective in increasing slab capacity than steel stiffeners, consequently different failure modes were observed.

Globally, construction industry plays a key role in development of an economy of any country. On the other side, construction projects suffer extensive delays and cost overruns exceeding by that the budgeted money and the estimated time. Therefore, adopting techniques like optimization technique in construction media became a necessity for preventing the actual cost and execution time of projects from exceeding the planned cost and estimated time, respectively. Since, concrete is the most essential construction and the most used material in construction projects construction where it influences extremely gross domestic products of numerous nations in the world, a multiobjective mathematical model with mixed linear and binary constraints is developed to specify the optimal solution of differently designed concrete slabs to impact loads. Eight concrete slabs had various design parameters, such as concrete thickness, steel fiber ratio, reinforcement ratio, and steel stiffener thickness are used in this study. The mathematical model comprised two objective functions: minimization cost and time, and had a number of constraints like concrete ingredients, load, deflection, and weight. The outputs of the developed model revealed a variety of slab design combinations with different cost, time, and deadloads depending on the limitations of serviceability loads.

. In construction industry, projects are usually completed in a budget more than what is estimated for, finished in a time more than the contracted time, not executed properly according to the specifications, and not constructed with the client satisfaction. The thing that causes lowering the profits of contractors, clients losing, time to market prolonging, and other consequences. Projects execution on or under the budgeted money requires valid practices, precise decisions, good strategies, and needs developing new techniques, such as cost reduction technique. Thus, this paper mainly aims to relieving part of the big concerns of those who specialized in construction media respecting construction cost overruns by determining the most economical structural design, which can be realized by studying, quantifying, analysing cost, and comparing a number of structural elements with different dimensions, different design combinations, and different materials proportions. Then, the optimum structural element, the element that meets the design requirements, comprises the least materials quantities, and costs least, was selected in case to achieve an economical construction.

In the recent years, researchers have been interested in planning of layout of projects´ site since it is a basic factor for a successful project undertaking. Projects´ sites comprise temporary facilities and heavy construction equipment that share the same space or may require the same area of construction site, therefore, construction site should be organized well, so that construction activity will be in its full swing. The site layout planning process includes identifying the needed temporary facilities for supporting operations of construction, specifying their shapes and sizes, and optimizing their positions within the boundaries of sites. In this review, a number of methods and techniques used for construction site layout planning are reviewed and discussed, the frequent problems at construction sites are included, the ways of improving the efficiency of planning of sites layout are listed and discussed. The advantages of good planning of sites layout and the effects of neglecting sites layout planning are reviewed.

Fibrous concrete is an enhanced material by adding fibers to the ingredients of normal concrete. This addition improved some properties of the regular concrete, which are growing concrete ductility, decreasing concrete shrinkage, and raising concrete resistance to the dynamic attacks. The aim of this paper is more investigating the properties of fibrous concrete by finding out the effect of impact loading induced by a free fall ball on flexural capacity of fibrous concrete from one side, and finding out the importance of camber construction in reducing the influence of impact loading on the flexural capacity of concrete slabs from another side. For that purpose, three concrete slabs of (80X80X4) cm dimensions were dynamically and then statically loaded. The three specimens had the same steel fiber dosage of 0.5%, but they had different slab camber at the mid span where one specimen had no camber, the second specimen had 10 mm camber, and the third specimen had 20 mm camber. In addition to the difference in the slabs´ camber, the three slabs were subjected to a different number of impacts and from various heights to get a better explanation. Tests results showed that presence of fibers and increasing slab camber caused an improvement in the specimen resistance to both of impact and flexural loads, decreased the specimen crack width and number, and provided a safer residence for tenants.

One way to provide safe buildings and to protect tenants from the terrorist attacks that have been increasing in the world is to study the behavior of buildings members after being exposed to dynamic loads. Buildings behaviour after being exposed to attacks inspired researchers all around the world to investigate the effect of impact loads on buildings members like slabs and to deeply study the properties of High Performance Concrete. HPC is well-known in its high performance and resistance to dynamic loads when it is compared with normal weight concrete. Therefore, the aim of this paper is finding out the impact of dynamic loads on RPC slabs’ flexural capacity, serviceability loads, and failure type. For that purpose and to get answers for these questions, three concrete slabs with 0.5, 1, and 2% steel fiber contents were experimentally tested. The tests results showed that the content of steel fiber plays the key role in specifying the static capacity of concrete slabs after being dynamically loaded, and increasing the content of steel fiber led to improving the static loading capacity, decreased the cracks numbers and widths at the same time, and provided a safer environment for the buildings residents.