Project 1

Project 1: Omrania Tower, it is a private, non-governmental building, it is residential & commercial tower(See to below image). One of the more challenging projects I analyzed and studied the seismic evaluation of the 14th floors concrete structure consists of shear walls, columns, solid slabs & raft foundation. The building consists of 14 floors; basement (garage), ground (commercial), first (commercial) , eleven residential typical floors. It is located in Omrania District, Giza government, Egypt. It was constructed at 2017. The total construction cost was 40 million Egyptian pounds. The building was previously designed according to Egyptian code for the design and execution of reinforced concrete structures: Code No. ECP 203-2007. During the study, the building was without any finishing and masonry partitions (concrete skeleton only). The all shear walls in the structure were ended at eighth floor(The upper six floors are without shear walls; supported by columns only). The client requested to evaluate the overall structural safety of the building and submitting the suitable design of repair, retrofitting and strengthening methods if required. - I followed the guidelines in the ACI 562-16 code (Code Requirements for Assessment, Repair, and Rehabilitation of Existing Concrete Structures and Commentary). - I performed specialized detailed inspections that included core test in some locations of the columns & shear walls in the building to define the actual concrete compressive strength. - I performed the cement content test, chloride content & sulfate content for hardened concrete. - Firstly, I performed the structural analysis of existing structure under gravity loads only (dead & live loads) and I checked the capacity of the columns for gravity loads resistance according to ECP 203-2018 and ECP 201-2012: Egyptian Code for Calculating Loads and Forces in Structural Work and Masonry . All columns were safe under gravity loads. Csi Etabs software was used to show the actual straining actions in the columns under vertical gravity loads. 3D Analytical model is shown in below image. - Secondly, I performed seismic (response spectrum) analysis according to Egyptian Code for Calculating Loads and Forces in Structural Work and Masonry(ECP-201). I used Csi Etabs software also for seismic analysis. The structure was slightly unsafe under lateral seismic loading. Besides, high moment values were noticed at the base of shear walls, this lead to that the cross sections of most shear walls, and interior cores were unsafe. I took a decision to reduce the mass of the building (to reduce the seismic load) by reducing both dead & live loads for all stories. So that it does not affect the functionality of the building as possible. I re-calculate and re-evaluate the building again based on this idea. All sections became safe & and the building recorded inter-story drift values lie within permissible limits. My idea attained an economical solution; instead of spending millions of pounds for seismic strengthening of the structure. - Besides, I took an important decision, that was conducting chlorides content test in concrete in some locations in the building. I was surprised that the chloride content is high and exceed than the maximum permissible limit according to ECP 203- 2007. This indicates that all the steel reinforcement in the building will soon be exposed to corrosion. To save the building, I recommended the work of cathodic protection for steel reinforcement to prevent corrosion in the future, and by this I saved the building from deterioration due to steel corrosion, and I saved much of millions of pounds that would be spent in repairing and retrofitting of the building in case of steel bars corrosion.