It was not the earthquake. It was the poor construction methodology that killed more than 85,000 people. What's worse, habitancy have started constructing their houses by using the old technique of placing stone in walls. Again cement is being used as mortar for stone wall and they have failed to learned the lesson from the up-to-date devastating earthquake. Detailed prognosis of damaged structures demonstrated that stone wall using cement mortar or mud was the main cause of casualties.
Construction of stone masonry rural houses using/recycling construction materials such as Gi roofing sheets and timber from their damaged houses and in effect ready rubble from collapsed houses will be the most cost-effective and realistic and practicable advent for hereafter construction.
Earthquake & Tsunami In Japan
The core of the GoP's assistance to affected households in both urban and rural areas should be cash grants for basic housing assistance. The grants should be released in installments based on stages of construction, with technical assistance for introduction of seismic features in case,granted by local governments and/or provincial line agencies. There should be few categories of grant so that their supervision is simple. In this scheme, households will be able to utilise their own labour, use hired labour, or enter into an arrangement with a partner organisation/Ngo to rehabilitate or reconstruct their houses. However, close monitoring of reconstruction processes adopted will be crucial.
The objective of this practical reconstruction strategy is to rebuild the rural katcha houses by reusing the rubble of collapsed house to sacrifice the debris disposal cost of 9000 million rupees and to maximise the local capacity construction in earthquake resistant construction techniques.
The significance of configuration is well recognised in modern techniques to produce earthquake-resistant buildings. Configuration has to do with the shape and size of the building. Inevitably shape and size to a large extent determines (or greatly influences) the type, shape, arrangement, size, location and most other aspects of the structural concept.
As stated earlier, the main contributor and the principle cause of deaths in the up-to-date earthquake is the total or partial collapse of buildings. About 95 per cent of fatalities, however, are caused by the collapse of primarily are weak masonry structure (adobe, rubble stone, or rammed earth) or un-reinforced brick and concrete block masonry that collapsed.
Another factor is the irregular geometric shape of the buildings. In Rawalakot during the up-to-date earthquake, most modern structure collapsed except the six-sided polygon shaped aged temple built hundreds of years ago based on unavoidable system of construction. Dome and hexagon are the fundamental, essential, and excellent form of structure to disperse seismic troops equally in all directions and are therefore safe in case of natural calamities. Irregular shapes corollary in uneven distribution of forces, thereby development structure prone to collapse.
The heavy damage to many of the structure could be attributed to poor construction practices and irregular geometric shapes. The former load-bearing elements are the walls. Hence, the failure of these masonry walls in out-of-plane bending and in-plane shear has resulted in structural collapse or heavy damage. Shear cracks were observed though stone masonry as well as mortar. Many of the industrial structure of reinforced concrete frame and slab construction with masonry have suffered collapse or widespread damage in all earthquakes.
Deviation from earthquake resistant produce doctrine is greatly observed in collapse of the 11-storey residential apartment structure in the Margalla Towers complex Islamabad, constructed just over 10 years ago. The construction has a basement and therefore the basement floor is a soft storey as shown in photograph. The soft storey understanding is very dangerous in earthquakes.
It's again a underlying issue for builders and architects to understand that while designing and constructing a construction in earthquake prone area, its size and shape is a basic factor to be considered. Other factors like the height of a construction in an earthquake (which exhibits horizontal forces) is analogous to the length of a cantilever. It is self evident that increasing height increases earthquake-resisting qoute exponentially, all other things being equal. Height affects the natural vibrating period of the building. The higher the construction the longer its period. Depending on the nature of the earthquake and the nature of the founding soils, increasing the period may growth or sacrifice the response of the building. Limiting the height/width ratio, keeps the overturning qoute within reasonable bounds. In particular, large overturning moments on narrow footprints can lead to high compressive troops on outer columns. These can be very difficult to deal with.
An important characteristic missing in the collapsed structure is their symmetry. This characteristic applies to horizontal plan shape as well as to vertical elevation shape. There are many cases of false symmetry observed where the centre of mass of the construction did not coincide with the centre of resistance, although the outward appearance of the construction may be symmetrical. The temple is showing perfectness in its symmetry.
Another favourable characteristic of earthquake-resistant structures is redundancy. Redundant structures contribute multiple load paths so that the premature failure of one (or a few) elements would not lead to the catastrophic and sudden collapse of the building. The most favourable locations of vertical elements for resisting horizontal loads is at the perimeter of the building. This is so because such locations contribute the most lever arm for resisting overturning moments. A non-structural detailing recipe for in-fill block walls often produces short columns. These columns absorb more than their incredible share of the lateral loads from earthquakes, important to shear failure. Disunion joints are used for several reasons in buildings. When this is done the joint between the adjacent parts of the construction must be sufficiently wide to avoid hammering during an earthquake. another issue to be addressed with Disunion joints is the flexibility of mechanical services as they cross the joint.
The commonly-accepted aim of good earthquake-resistant produce is to bring about 'failure' (or yielding) of the beam before failure of the contiguous column takes place. This characteristic is described as strong column weak beam. The coarse hindrance to this desirable highlight is the spandrel beam at the perimeter of a building. These are often quite deep for architectural reasons and can be quite an embarrassment for the structural design.
"Building Blocks" building Methodology And Earthquake - 2005