STRUCTURAL ANALYSIS & DESIGN FOR THE PROPOSED ___________________,CAGAYAN DE ORO CITY 1.0 CODE AND SPECIFICATIONS: The following structural codes and specifications shall be used in the structural analysis and design of the reinforced concrete special moment resisting 3 – Storey school building structure. 1. National Structural Code of the Philippines 2015, NSCP2015, Volume 1 – Generally for the entire Analysis and Design Requirements 2. Uniform Building Code 1997 Edition, UBC97 – For Building Seismic Analysis
2.0 MATERIAL STRENGTHS: The following material strengths shall follow the specifications used for the 2 storey building, i.e.: Material Properties:
As per original design criteria
Minimum Concrete Compressive Strength, f’c: Columns: fc’ = 21MPa(3000 psi) Beams:
fc’ = 21MPa(3000 psi)
Slabs:
fc’ = 21MPa(3000 psi)
Footing:
fc’ = 21MPa(3000 psi)
Reinforcement steel bars shall be deformed and shall conform to ASTM 615 Main Bars,(16mm or larger)
fy = 276MPa(Grade 40)
Secondary Bars, (12mm>)
fy = 228MPa(Grade 33)
3.0 LOADS: Design Loads and forces are those resulting from the self-weight of the building including all other permanent loads referred to as the Dead Loads, occupancy or non-permanent loads referred to as the Live Loads, and earthquake loads as sometimes called as Seismic Loads acting in most critical combinations using the appropriate load factors as recommended by the governing national structural code of the Philippines.
3.1 Dead Loads: Dead Loads consist of the self-weight of the building structural frame and all materials and fixed equipment incorporated into the building or other structure, including but not limited to walls, floors, roofs, ceiling, stairways, built-in partitions, finishes, cladding and other similarly incorporated architectural and structural items, and fixed service equipment. Below shows the design dead loads used in the analysis and design of the building.
Materials
Unit Dead Loads
3.2 Live Loads: Live loads are the non-permanent loads acting on the floor area which include varying loads due to occupancies during the life of the structure; not including wind and earthquake loads. Live loads shall be the maximum loads expected by the intended use or occupancy but in no case shall be less than the loads required by Section 205 of the NSCP 2010. Below are the design live loads used in this design. Occupancy / Use
Floor Live Loads
3.3 Seismic Loads: The vibratory ground motion caused by the earthquake can have damaging effects on structure and can even lead to collapse. It is extremely important to consider seismic effect in the design of the building in the Philippines because of the fact that the country generally falls in a high seismic-risk zone. NSCP 2010 Section 208 provides a general procedure in dealing with Seismic loads which is patterned from the Uniform Building Code. The structure limitations and design is guided with seismic zoning, field characteristics, occupancy and structural configuration. Below are the Seismic analysis parameters for calculation of the lateral seismic forces on the building structure: Occupancy Category:
Essential Occupancy Table 103-1 of Section 103
Occupancy Importance Factor, I: 1.5
Table 208-1, Section 208.4.2 Public School Building
Seismic Zone Factor, Z: 0.40
Table 208-3, Section 208.4.4.1
Nearest Source Factors: 17.2 kM Nearest to Tagoloan River Fault
Seismic Source Type:
1.0
Near-Source factor, Na
Table 208-4
1.0
Near-Source factor, Nv
Table 208-5
A
Faults with Max. Moment Magnitude greater than 7 Moment-Resisting Frame Structure: Special Reinforced Concrete Moment Frame Seismic Resistance factor:
8.5
Table 208-11A
3.4 Loading Combination: Considering that earthquake load , E, is as specified under section 208.6.1 which is equal to: E = pEh + Ev As per Section 203.3 of the NSCP2015 7th Edition 1.4 Dead Load
(203-1)
1.2 Dead Load + 1.6 Live Load + 0.5 Roof Live Load
(203-2)
1.2 Dead Load + 1.0 Live Load + 1.6 Roof Live Load
(203-3)
1.53 Dead Load + 1.0 Earthquake + (f1)Live Load
(203-5)
3.5 Foundation Soil: The allowable soil bearing capacity of the site can be as high as ____kPa. Contractor shall conduct the necessary soil exploration to determine the configuration of the soil and to design appropriate foundation of the building. 3.6 Analysis and Design Methods: Building analysis used herein is a 3-dimensional analysis method using a computer software. Seismic analysis to calculate the lateral force used is following the procedure as stipulated in the Uniform Building Code, UBC 1997.In this Building Analysis, the Static Lateral Force procedure under NSCP 2015 shall be used because the building to be designed belongs to the seismic zone 4 with a height of not more than 75 meters. The structure is somehow regular in shape though some irregularities may have been incorporated but the building is still at a height for a 5-storey building. Design method used is the Ultimate Strength Design method for the reinforced concrete structures including but not limited to beams, columns, slabs and stairs. The design calculation is governed by the current ACI 318-14 and NSCP 2015 codes, with the seismic provision in Section 418 of NSCP-2015. Furthermore, the building shall be designed with seismic connection details to be ductile and to conform to the requirements for being a special moment resisting concrete frame structure. The in-fill masonry partitions are assumed to have no stiffening effect on the structure. 3.7 Structural Detailing: Structural detailing shall follow the requirements stated in Section 418 – Earthquake-Resistant Structures and the Reinforcement Detailing as stated in Section 425 in the NSCP-2015.
Prepared by:
Civil/Structural Engineer PRC NO: PTR NO.:
DATE: T.I.N.:
01 – __ – 17
